High speed energy switching

Abstract

An example particle therapy system can include a synchrocyclotron to generate a particle beam, a scanner to move the particle beam in one or more dimensions relative to an irradiation target, and an energy degrader between the scanner and the irradiation target. The energy degrader can include a plurality of plates that are movable relative to a path of the particle beam and each controllable to move in the path of the particle beam and during movement of the particle beam. An aperture can be between the energy degrader and the irradiation target. The aperture can trim the particle beam before the particle beam reaches the irradiation target.

Description

[0001] This application is a continuation of, and claims priority to, application serial number 201780087400.2, filed December 20, 2017.

[0002] Cross Reference to Related Applications

[0003] This application is a continuation of, and claims priority to, U.S. Patent Application No. 14 / 137,854, filed December 13, 2013, entitled "Collimator and Energy Degrader." U.S. Patent Application No. 14 / 137,854 is incorporated herein by reference. TECHNICAL FIELD

[0004] The present disclosure relates generally to an energy degrader that is configurable to change the energy of a particle beam. BACKGROUND

[0005] Particle therapy systems use accelerators to generate particle beams to treat afflictions, such as tumors. In operation, particles are accelerated in orbits within a cavity in the presence of a magnetic field, and are removed from the cavity through an extraction channel. A magnetic field regenerator generates magnetic field inhomogeneities near the outside of the cavity to twist the spacing and angle of some of the orbits so that they precess toward the extraction channel and eventually enter the extraction channel. A beam composed of the particles exits the extraction channel.

[0006] A scanning system is downstream of the beam of the extraction channel. In this context, "downstream" means closer to the irradiation target (here, relative to the extraction channel). The scanning system moves the beam across at least a portion of the irradiation target to expose portions of the irradiation target to the beam. For example, to treat a tumor, the particle beam can be "scanned" over different cross sections of the tumor. The energy degrader changes the energy of the particle beam to reach different cross sections of the tumor. SUMMARY

[0007] An example particle therapy system includes a particle accelerator to output a particle beam, and an energy degrader that is controllable to pass the particle beam to an irradiation target, at least a portion of the energy degrader can be controllable to move during the passing of the particle beam to the irradiation target. The example particle therapy system can include one or more of the following features, alone or in combination.

[0008] The energy degrader includes a plate (e.g., a plurality of plates) that is movable. The plurality of plates can include a first plate and a second plate that are controllable to move during the passing of the particle beam. The second plate is controllable to follow the first plate during the moving, or the first plate is controllable to follow the second plate during the moving.

[0009] An example particle therapy system can include a scanner that is controllable to move a particle beam in one or more dimensions relative to an irradiation target. At least one of the energy degrader or the scanner can be controllable to cause the particle beam to pass through the first plate but not the second plate, or to pass through the second plate but not the first plate during movement of the first and second plates. At least one of the energy degrader or the scanner is controllable to cause the particle beam to pass through both the first and second plates during movement of the first and second plates. Movement of the particle beam across the plates among the plurality of plates is limited to movement outside of a predetermined distance from an edge of the plate.

[0010] An energy degrader can include a plurality of plates including a first plate and a second plate that are controllable to move during passage of a particle beam. The first and second plates can move from a start position to an end position during movement of the first and second plates. The particle beam can be controllable to move from a position toward the end position such that the particle beam passes through both the first and second plates, or through only one of the first or second plates. The particle beam can be controllable to move from a position toward the start position such that the particle beam passes through both the first and second plates, or through only one of the first or second plates.

[0011] The plurality of plates of an energy degrader can include one or more first plates and one or more second plates. The one or more first plates and the one or more second plates can be controllable to move relative to a particle beam. A thickness of each of the one or more first plates can be less than a thickness of the one or more second plates. A thickness of a first plate among the one or more first plates can be a fraction of a thickness of each of the one or more second plates. For example, the thickness of the first plate can be half of the thickness of each of the one or more second plates.

[0012] Control of movement of the plurality of plates of an energy degrader can include sequencing movement of the plurality of plates such that each layer of a plurality of layers of an irradiation target is subjected to a particle beam. Control of movement of the plurality of plates can include sequencing movement of the plurality of plates such that the plurality of layers of the irradiation target are treated with the particle beam out of order. Control of movement of the plurality of plates can include sequencing movement of the plurality of plates such that an energy of the particle beam corresponds to a position of each layer of a plurality of layers of an irradiation target.

[0013] An example particle therapy system can include an aperture that is controllable to trim a spot of a particle beam. The aperture can be between an irradiation target and an energy degrader. The energy degrader can include one or more plates that are movable relative to the irradiation target during passage of the particle beam. A dimension of each of the one or more plates can be less than a dimension of an irradiation field.

[0014] An example particle therapy system can include a synchrocyclotron to generate a particle beam, a scanner to move the particle beam in one or more dimensions relative to an irradiation target, and an energy degrader between the scanner and the irradiation target. The energy degrader can include a plurality of plates movable relative to a path of the particle beam. The plurality of plates can each be controllable to move in the path of the particle beam and during movement of the particle beam. An aperture can be between the energy degrader and the irradiation target. The aperture can be controllable to trim the particle beam before the particle beam reaches the irradiation target. The example particle therapy system can include one or more of the following features, alone or in combination.

[0015] An example particle therapy system can include an outer gantry on which the synchrocyclotron is mounted, the outer gantry configured to move the synchrocyclotron at least partially around the irradiation target, and an inner gantry within a sweep of the outer gantry, the inner gantry including a nozzle on which the energy degrader is mounted, the inner gantry configured to move the energy degrader based on movement of the outer gantry.

[0016] The plurality of plates can include a first plate and a second plate controllable to move in a first direction and a second direction during passage of the particle beam. The first direction can be from a start position to an end position, and the second direction can be from the end position to the start position. At least one of the scanner or the energy degrader can be controllable to cause the particle beam to pass through either only the first plate, or only the second plate, or both the first plate and the second plate during movement of the first plate and the second plate in the first direction. At least one of the scanner or the energy degrader can be controllable to cause the particle beam to pass through either only the first plate, or only the second plate, or both the first plate and the second plate during movement of the first plate and the second plate in the second direction.

[0017] The first plate and the second plate can be controllable to move separately during application of the particle beam. The second plate can be controllable to follow the first plate during movement, or the first plate can be controllable to follow the second plate during movement. At least one of the energy degrader or the scanner can be controllable to cause movement of the particle beam during movement of the first plate and the second plate such that the particle beam passes through the first plate but not the second plate, or passes through the second plate but not the first plate. At least one of the energy degrader or the scanner can be controllable to cause movement of the particle beam during movement of the first plate and the second plate such that the particle beam passes through both the first plate and the second plate. Movement of the particle beam across a plate among the plurality of plates is limited to movement outside a distance from an edge of the plate.

[0018] During movement of the first plate and the second plate, the first plate and the second plate can move from a start position to an end position. The scanner can be controllable to move the particle beam from a position toward the end position such that the particle beam passes through both the first plate and the second plate, or through only one of the first plate or the second plate. The scanner can be controllable to move the particle beam from a position toward the start position such that the particle beam passes through both the first plate and the second plate, or through only one of the first plate or the second plate. The plurality of plates can include one or more first plates and one or more second plates, the one or more first plates and the one or more second plates being controllable to move during application of the particle beam, and a thickness of each of the one or more first plates being less than a thickness of the one or more second plates. A size of each of the plurality of plates can be less than a size of a radiation (or beam) field.

[0019] An example particle therapy system can be configured to apply a particle beam to an irradiation target. The example particle therapy system includes a scanner to move the particle beam in one or more dimensions relative to the irradiation target, and an energy degrader including an element controllable to move during movement of the particle beam. The energy degrader is to pass the particle beam through the energy degrader prior to application of the particle beam to the irradiation target. The example particle therapy system can include one or more of the following features, alone or in combination.

[0020] The element can include a plate controllable to move in a sequence to change an energy of the particle beam such that different layers of the irradiation target are subjected to the particle beam. The element can include a first plate and a second plate, both the first plate and the second plate being controllable to move during movement of the particle beam. At least one of the energy degrader or the scanner can be controllable to cause the particle beam to pass through the first plate but not the second plate, or to pass through the second plate but not the first plate, during at least part of the movement of the first plate and the second plate. At least one of the energy degrader or the scanner can be controllable to cause the particle beam to pass through both the first plate and the second plate during at least part of the movement of the first plate and the second plate. At least one of the energy degrader or the scanner can be controllable to cause the particle beam to not pass within at least a distance from an edge of at least one of the elements. The distance can be based on a distribution of particles in a spot representing a cross-section of the particle beam at the at least one of the elements.

[0021] The element can be controllable to move in at least one of a first direction or a second direction during movement of the particle beam, the first direction being from a start position of the element to an end position of the element, and the second direction being from the end position to the start position. At least some of the elements can be controllable to move separately during movement of the particle beam. At least some of the elements can be controllable to move together during movement of the particle beam. A size of each of the plurality of elements can be less than a size of an irradiation field.

[0022] An example particle therapy system includes a particle accelerator to output a particle beam; and, a scanning system of the particle accelerator to scan the particle beam across at least a portion of an irradiation target. The scanning system is configured to scan the particle beam in two dimensions at an angle relative to a direction of the particle beam. A structure defines an edge. The structure is controllable to move in the two dimensions relative to the irradiation target such that at least a portion of the structure is between at least a portion of the particle beam and the irradiation target. The structure includes a material that inhibits transmission of the particle beam. The example particle therapy system can include one or more of the following features, alone or in combination.

[0023] The structure can be rotatable in at least two dimensions such that the edge can move between different portions of the irradiation target and the particle beam. The edge can include a curve having a radius that varies on at least one side of the structure. The curve can be a french curve. The structure can define an aperture and the edge can include an edge of the aperture. The structure can be movable to track a direction of the particle beam. The structure can include a plurality of elements that are adjustable to change a size of the edge. The plurality of elements can include fingers that are independently movable relative to the irradiation target.

[0024] The structure can be part of a collimator system. The structure can include a first structure in the collimator system and the edge can include a first edge. The collimator system can include a second structure that includes a second edge. The first edge and the second edge can be controllable to move along different edges of the irradiation target.

[0025] The scanning system can include at least one magnet to control movement of the particle beam to scan the particle beam. The at least one magnet can be to generate a magnetic field in response to an applied current. The magnetic field can affect the movement.

[0026] The scanning system can be configured to scan the particle beam faster in an interior region of the irradiation target than at an edge of the irradiation target. The particle beam can be movable within an area of a plane at a location of the structure. The area of the structure can be less than the area of the plane. The area of the structure can be less than half of the area of the plane. The area of the structure can be less than a quarter of the area of the plane. The area of the structure can be less than an eighth of the area of the plane. The area of the structure can be less than ten times a cross-sectional area of the particle beam.

[0027] The scanning system can be configured to scan the particle beam from different incident angles. As the particle beam is scanned from the different incident angles, the structure can be controllable to move based on movement of the particle beam. The scanning system can include a magnet to affect a direction of the particle beam to scan the particle beam across at least a portion of an irradiation target; and, a degrader to change an energy of the beam prior to outputting the particle beam to the irradiation target, where the degrader is downstream of the beam from the magnet relative to the particle accelerator. The particle accelerator can be an energy variable device.

[0028] A particle accelerator can include a voltage source to provide a radio frequency (RF) voltage to a cavity to accelerate particles from a plasma column, where the cavity has a magnetic field that causes the particles to accelerate from the plasma column to move orbitally within the cavity; an extraction channel to receive the particles accelerated from the plasma column and output the received particles from the cavity; and a regenerator to provide a magnetic field inhomogeneity within the cavity to change successive orbits of the particles accelerated from the plasma column such that a final particle is output to the extraction channel. The magnetic field can be between 4 Tesla (T) and 20 T, and the magnetic field inhomogeneity is at most 2 Tesla.

[0029] An example particle therapy system includes a particle accelerator to output a particle beam; and a scanning system to receive the particle beam from the particle accelerator and to perform a scan of at least a portion of an irradiation target with the particle beam. The scanning system includes a structure defining an edge. The structure is controllable to move in two dimensions and is moved based on movement of the particle beam such that the edge is between at least a portion of the particle beam and the irradiation target. The structure includes a material that inhibits transmission of the particle beam. The example system also includes a gantry on which the particle accelerator and the scanning system are mounted. The gantry can be configured to move the particle accelerator and the scanning system around the irradiation target.

[0030] An example particle therapy system includes a synchrocyclotron to output a particle beam; a magnet to influence a direction of the particle beam to move the particle beam across a cross-section of an irradiation target; a degrader to change an energy of the particle beam before moving the particle beam across an interface of the irradiation target, where the degrader is downstream of the magnet relative to the synchrocyclotron; and one or more processing devices to control movement of the degrader such that the degrader at least partially tracks movement of the particle beam at an irradiation plane. The example particle therapy system can include one or more of the following features, alone or in combination.

[0031] The particle beam can be moveable within an area of a plane at a location of the degrader. The area of the degrader can be less than the area of the plane. The degrader can include a plurality of pieces, each piece composed of a beam energy absorption material, and each piece moveable into a path of the particle beam. The one or more processing devices can be programmed to receive an energy of the particle beam to be applied to the irradiation target and to move one or more of the pieces of the beam energy absorption material into the path of the particle beam such that a resulting energy of the particle beam approximates the energy of the particle beam to be applied to the irradiation target. The one or more processing devices can be programmed to control movement of the one or more pieces of the beam energy absorption material to at least partially track movement of the particle beam.

[0032] The area of the degrader can be less than half the area of the plane. The area of the degrader can be less than one quarter the area of the plane. The particle beam has a spot size at the location of the degrader; and the area of the degrader can be less than ten times the area of the spot size. The area of the degrader can be less than twice the area of the spot size.

[0033] The particle therapy system can include a memory to store a treatment plan. The treatment plan can include information to define a scan pattern for the irradiation target. The scan pattern can define movement of the particle beam in two dimensions and movement of the degrader such that the degrader at least partially tracks movement of the particle beam.

[0034] The synchrocyclotron can include a voltage source to provide a radio frequency (RF) voltage to a cavity to accelerate particles from a plasma column, wherein the cavity has a magnetic field that causes the particles accelerated from the plasma column to move orbitally within the cavity; an extraction channel to receive the particles accelerated from the plasma column and output the received particles from the cavity as part of a particle beam; and a regenerator to provide a magnetic field inhomogeneity within the cavity to change successive orbits of the particles accelerated from the plasma column such that the particles are ultimately output to the extraction channel. The magnetic field can be between 4 Tesla (T) and 20 T, and the magnetic field inhomogeneity can be up to 2 Tesla, and the synchrocyclotron can be an energy variable device.

[0035] The magnet and the degrader can be part of a scanning system. The particle therapy system can include a gantry on which the synchrocyclotron and the scanning system are mounted. The gantry can be configured to move the synchrocyclotron and the scanning system around the irradiation target.

[0036] The scanning system can be a raster scanning system, a spot scanning system, or any other type of scanning system

[0037] An example particle therapy system can include a particle accelerator to output a particle beam; and a scanning system to receive the particle beam from the synchrocyclotron and to perform a scan of at least a portion of an irradiation target with the particle beam. The scanning system can include a degrader to change an energy of the particle beam prior to scanning the at least a portion of the irradiation target. The degrader can be downstream of the beam of the magnet relative to the synchrocyclotron. An example particle therapy system can include one or more processing devices to control movement of the degrader such that the degrader at least partially tracks movement of the particle beam; and a gantry on which the particle accelerator and the scanning system are mounted. The gantry can be configured to move the synchrocyclotron and the scanning system around the irradiation target. An example particle therapy system can include one or more of the following features, alone or in combination.

[0038] The particle beam can be movable within an area of the plane at the location of the downscaler. The area of the downscaler can be less than the area of the plane. The downscaler can include a plurality of pieces, each piece being a beam energy absorption material process, and each piece can be movable into the path of the particle beam. The one or more processing devices can be programmed to receive an energy of the particle beam to be applied to the irradiation target, and to move one or more of the pieces of beam energy absorption material into the path of the particle beam such that the resulting energy of the particle beam approximates the energy of the particle beam to be applied to the irradiation target. The one or more processing devices can be programmed to control movement of the one or more pieces of beam energy absorption material to at least partially track movement of the particle beam.

[0039] The area of the downscaler can be less than half the area of the plane. The area of the downscaler can be less than one quarter the area of the plane. The particle beam has a spot size at the location of the downscaler, and the area of the downscaler can be less than ten times the area of the spot size. The area of the downscaler can be less than twice the area of the spot size. The particle accelerator can be an energy-variable synchrocyclotron.

[0040] An example proton therapy system can include the foregoing particle accelerator and scanning system; and, a gantry on which the particle accelerator and scanning system are mounted. The gantry is rotatable relative to a patient. The protons are output substantially directly from the particle accelerator and through the scanning system to a location of an irradiation target, such as a patient. The particle accelerator can be a synchrocyclotron.

[0041] Two or more features described in this disclosure, including those described in the SUMMARY, can be combined to form embodiments not specifically described herein.

[0042] Control of the various systems described herein, or portions thereof, can be implemented via a computer program product, including instructions stored on one or more non-transitory machine-readable storage media, and executable on one or more processing devices. The systems described herein, or portions thereof, can be implemented as an apparatus, method, or electronic system, which can include one or more processing devices and memory to store executable instructions to implement the described functionality.

[0043] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 and Figure 2 is a cross-sectional view of an example synchrocyclotron configuration for use in a particle therapy system;

[0045] Figure 3is a side view of an example scanning system;

[0046] Figure 4 is a perspective view of components of an example scanning system, except for the scattering material for spot size variation;

[0047] Figure 5 is a perspective view of components of an example scanning system, except for the scattering material for spot size variation; Figure 3 and Figure 4 is a front view of an example magnet in a scanning system of the type shown in

[0048] Figure 6 is a front view of an example magnet in a scanning system of the type shown in Figure 3 and Figure 4 is a perspective view of an example magnet in a scanning system of the type shown in

[0049] Figure 7 is a perspective view of an example magnet in a scanning system of the type shown in Figure 3 and Figure 4 is a perspective view of an example energy degrader (range modulator) in a scanning system of the type shown in

[0050] Figure 8 is a perspective view of a plate that moves an energy degrader in the path of a particle beam;

[0051] Figure 9 is a side view of an example particle beam and collimator;

[0052] Figure 10 is a top view showing an example cross-section of an irradiation target, an example collimator movable along an edge of the cross-section, and an example beam along an internal scan path of the irradiation target;

[0053] Figure 11 is a top view of an example collimator;

[0054] Figure 12 is a top view of components of an example collimator;

[0055] Figure 13 is a top view showing components of Figure 12 combined to form an example collimator;

[0056] Figure 14 is a top view showing an example cross-section of an irradiation target, and an example multi-leaf collimator movable along an edge of the cross-section during scanning of a particle beam;

[0057] Figure 15 is a top view showing an example cross-section of an irradiation target, and an example straight-edge collimator movable and rotatable along an edge of the cross-section during scanning of a particle beam;

[0058] Figure 16is a top view showing an example cross-section of an irradiation target, an example multi-component collimator movable along the edges of the cross-section during particle beam scanning, and an example beam scan path along the interior of the irradiation target;

[0059] Figure 17 is a top view of an example curved collimator;

[0060] Figure 18 is a view showing an example cross-section of an irradiation target, and an example of how intensity modulated proton therapy is performed on the irradiation target;

[0061] Figure 19 is a perspective view of an example irradiation field of a particle beam scanning system;

[0062] Figure 20 is a perspective view of multiple pieces of an example energy degrader in a beam path to an irradiation target;

[0063] Figure 21 is a perspective view illustrating movement of pieces of an energy degrader to track a scan of a particle beam;

[0064] Figure 22 is a perspective view illustrating situations in which movement of pieces of an energy degrader is needed, not needed to track a scan of a particle beam;

[0065] Figure 23 is a perspective view of an example treatment system;

[0066] Figure 24 is an exploded perspective view of components of an example synchrocyclotron for use in a particle therapy system;

[0067] Figure 25 is a cross-sectional view of an example synchrocyclotron;

[0068] Figure 26 is a perspective view of an example synchrocyclotron;

[0069] Figure 27 is a cross-sectional view of an example ion source for use in a synchrocyclotron;

[0070] Figure 28 is a perspective view of an example dee plate and an example dummy dee for use in a synchrocyclotron;

[0071] Figure 29 shows a patient positioned within an example internal gantry of an example particle therapy system positioned in a treatment room;

[0072] Figure 30 is a conceptual diagram of an example particle therapy system that can use an energy variable particle accelerator;

[0073] Figure 31 is an example plot of energy and current showing the variation in magnetic field and distance in a particle accelerator;

[0074] Figure 32 is a side view of an example structure for sweeping the voltage over a range of frequencies for each energy level of a particle beam on a D-shaped plate and for varying the range of frequencies as the particle beam energy varies;

[0075] Figure 33 is a perspective exploded view of an example magnet system that can be used in an energy variable particle accelerator;

[0076] Figure 34 is a block diagram showing an example particle therapy system including a switching energy degrader;

[0077] Figure 35 is a perspective view of an example irradiation target including multiple layers that are to be treated by a particle therapy;

[0078] Figure 36 is a perspective view of example plates of a switching energy degrader having the same thickness;

[0079] Figure 37 is a perspective view of example plates of a switching energy degrader having different thicknesses;

[0080] Figure 38 is a perspective view showing the plates of an example energy degrader moving apart during a scan in a forward direction;

[0081] Figure 38A is a perspective view showing a plate of an example energy degrader at a first position during a scan in a forward direction;

[0082] Figure 38B is a perspective view showing a plate of an example energy degrader at a second position during a scan in a forward direction;

[0083] Figure 39 is a view showing a Gaussian distribution of a particle beam spot;

[0084] Figure 40 is a perspective view showing the plates of an example energy degrader moving apart during a scan in a forward direction;

[0085] Figure 41 is a perspective view showing the plates of an example energy degrader moving together during a scan in a reverse direction;

[0086] Figure 42 is a perspective view showing the plates of an example energy degrader moving together during a scan in a forward direction;

[0087] Figure 43 is a perspective view of plates of an example energy degrader moving apart during scanning in a reverse direction;

[0088] Figure 44 is a perspective view of plates of an example energy degrader moving together during scanning in a forward direction;

[0089] Figure 45 is a perspective view of plates of an example energy degrader moving apart during scanning in a reverse direction;

[0090] Figure 46 is a perspective view of plates of an example energy degrader moving together during scanning in a forward direction;

[0091] Figure 47 is a perspective view of plates that combine and move during scanning to hit layers within an irradiation target;

[0092] Figure 48 is a top perspective view of a plate containing sensors;

[0093] Figure 49 is a top perspective view of a plate illustrating a two-dimensional scan of the plate.

[0094] The same reference numbers in the figures identify the same elements. DETAILED DESCRIPTION

[0095] Described herein are examples of a particle accelerator for use in a system such as a proton or ion therapy system. An example particle therapy system includes a particle accelerator, in this example a synchrocyclotron, mounted on a gantry. The gantry enables the accelerator to be positioned for rotation about a patient, as explained in more detail below. In some embodiments, the gantry is steel and has two feet mounted for rotation on two corresponding bearings located on opposite sides of the patient. The particle accelerator is supported by a steel truss that is long enough to straddle the treatment area in which the patient lies and is attached at both ends to rotate the feet of the gantry. Due to the rotation of the gantry about the patient, the particle accelerator also rotates.

[0096] In an example embodiment, the particle accelerator (e.g., a synchrocyclotron) includes a cryostat holding one or more superconducting coils, each for conducting a current that generates a magnetic field (B). In this example, the cryostat uses liquid helium (He) to maintain each coil at a superconducting temperature, e.g., 4 degrees Kelvin (K). A magnetic yoke or smaller pole pieces are located within the cryostat and define a cavity in which particles are accelerated.

[0097] In this example embodiment, the particle accelerator includes a particle source (e.g., a Penning Ion Gauge - PIG source) to provide a plasma column to the cavity. Hydrogen gas is ionized to produce the plasma column. A voltage source provides a radio frequency (RF) voltage to the cavity to accelerate pulses of particles from the plasma column.

[0098] As mentioned, in examples, the particle accelerator is a synchrotron. Accordingly, the RF voltage is scanned across a range of frequencies to account for relativistic effects (e.g., increased particle mass) on the particles as they are accelerated from the plasma column. A magnetic field produced by running current through superconducting coils causes particles accelerated from the plasma column to orbitally accelerate within the cavity. In other embodiments, particle accelerators other than synchrotrons can be adapted. For example, cyclotrons, betatrons, linear accelerators, etc. can be substituted for the synchrotron described herein.

[0099] In the synchrotron, a magnetic field regenerator ("regenerator") is positioned outside the cavity (e.g., at its inner edge) to adjust the existing magnetic field within the cavity to change the position (e.g., spacing and angle) of successive orbits of particles accelerated from the plasma column so that the particles are ultimately output to an extraction channel that passes through the cryostat. The regenerator can increase the magnetic field at a point in the cavity (e.g., it can create a magnetic field "inhomogeneity" at a region of the cavity) so that each successive orbit of particles at that point precesses toward an entry point of the extraction channel until it reaches the extraction channel. The extraction channel receives particles accelerated from the plasma column and outputs the received particles from the cavity as a particle beam.

[0100] The superconducting ("main") coil can produce a relatively high magnetic field. The magnetic field generated by the main coil can be in the range of 4 T to 20 T or higher. For example, the main coil can be used to generate a magnetic field that is one or more of the following strengths, or exceeds one or more of the following strengths: 4.0 T, 4.1 T, 4.2 T, 4.3 T, 4.4 T, 4.5 T, 4.6 T, 4.7 T, 4.8 T, 4.9 T, 5.0 T, 5.1 T, 5.2 T, 5.3 T, 5.4 T, 5.5 T, 5.6 T, 5.7 T, 5.8 T, 5.9 T, 6.0 T, 6.1 T, 6.2 T, 6.3 T, 6.4 T, 6.5 T, 6.6 T, 6.7 T, 6.8 T, 6.9 T, 7.0 T, 7.1 T, 7.2 T, 7.3 T, 7.4 T, 7.5 T, 7.6 T, 7.7 T, 7.8 T, 7.9 T, 8.0 T, 8.1 T, 8.2 T, 8.3 T, 8.4 T, 8.5 T, 8.6 T, 8.7 T, 8.8 T, 8.9 T, 9.0 T, 9.1 T, 9.2 T, 9.3 T, 9.4 T, 9.5 T, 9.6 T, 9.7 T, 9.8 T, 9.9 T, 10.0 T, 10.1 T, 10.2 T, 10.3 T, 10.4 T, 10.5 T, 10.6 T, 10.7 T, 10.8 T, 10.9 T, 11.0 T, 11.1 T, 11.2 T, 11.3 T, 11.4 T, 11.5 T, 11.6 T, 11.7 T, 11.8 T, 11.9 T, 12.0 T, 12.1 T, 12.2 T, 12.3 T, 12.4 T, 12.5 T, 12.6 T, 12.7 T, 12.8 T, 12.9 T, 13.0 T, 13.1 T, 13.2 T, 13.3 T, 13.4 T, 13.5 T, 13.6 T, 13.7 T, 13.8 T, 13.9 T, 14.0 T, 14.1 T, 14.2 T, 14.3 T, 14.4 T, 14.5 T, 14.6 T, 14.7 T, 14.8 T, 14.9 T, 15.0 T, 15.1 T, 15.2 T, 15.3 T, 15.4 T, 15.5 T, 15.6 T, 15.7 T, 15.8 T, 15.9 T, 16.0 T, 16.1 T, 16.2 T, 16.3 T, 16.4 T, 16.5 T, 16.6 T, 16.7 T, 16.8 T, 16.9 T, 17.0 T, 17.1 T, 17.2 T, 17.3 T, 17.4 T, 17.5 T, 17.6 T, 17.7 T, 17.8 T, 17.9 T, 18.0 T, 18.1 T, 18.2 T, 18.3 T, 18.4 T, 18.5 T, 18.6 T, 18.7 T, 18.8 T, 18.9 T, 19.0 T, 19.1 T, 19.2 T, 19.3 T, 19.4 T, 19.5 T, 19.6 T, 19.7 T, 19.8 T, 19.9 T, 20.0 T, 20.1T, 20.2T, 20.3T, 20.4T, 20.5T, 20.6T, 20.7T, 20.8T, 20.9T, or higher. Moreover, the main coils can be used to generate magnetic fields in the range of 4T to 20T (or higher, or lower) not specifically listed above.

[0101] In some embodiments, such as the example shown in Figure 1 and Figure 2 , a large ferromagnetic yoke acts as a return for the stray magnetic field generated by the superconducting coils. For example, in some embodiments, the superconducting magnet can generate a relatively high magnetic field, e.g., 4T or higher, resulting in a significant stray magnetic field. In some systems, the stray magnetic field can adversely affect the operation of the accelerator. Figure 1 and Figure 2 , a relatively large ferromagnetic return yoke 100 acts as a return for the magnetic field generated by the superconducting coils. A magnetic shield surrounds the yoke. Together, the return yoke and the shield dissipate the stray magnetic field, thereby reducing the likelihood that the stray magnetic field will adversely affect the operation of the accelerator.

[0102] In some embodiments, the return yoke and shield can be replaced or augmented by an active return system. An example active return system includes one or more active return coils that carry current in a direction opposite to the current through the main superconducting coils. In some example embodiments, there is an active return coil for each superconducting coil, e.g., two active return coils - one for each superconducting coil (referred to as the "main" coils). Each active return coil can also be a superconducting coil that surrounds the corresponding main superconducting coil.

[0103] Current passes through the active return coils in a direction opposite to the direction of the current through the main coils. The current through the active return coils thereby generates a magnetic field that is opposite in polarity to the magnetic field generated by the main coils. Thus, the magnetic field generated by the active return coils is able to dissipate at least some of the relatively strong stray magnetic field caused by the corresponding main coils. In some embodiments, each active return can be used to generate a magnetic field between 2.5T and 12T or higher. Examples of active return systems that can be used are described in U.S. Patent Application No. 13 / 907,601 (U.S. Patent No. 8,791,656), filed May 31, 2013, the contents of which are incorporated by reference herein.

[0104] Referring to Figure 3 , at the output of the extraction channel 102 of the particle accelerator 105 (which can have the configuration shown in Figure 1 and Figure 2 ), is an example scanning system 106 that can be used to scan the particle beam across at least a portion of the irradiation target. Figure 4Examples of components of a scanning system are shown. These components include, but are not limited to, a scanning magnet 108, an ion chamber 109, and an energy degrader 110. Other components that can be integrated into a scanning system are not shown in Figure 4 , including, for example, one or more scatterers for changing the beam spot size.

[0105] In an example operation, the scanning magnet 108 is controllable in two dimensions (e.g., Cartesian XY dimensions) to direct the particle beam across a portion (e.g., a cross-section) of the irradiation target. The ion chamber 109 detects the dose of the beam, and feeds this information back to the control system to adjust the beam movement. The energy degrader 110 is controllable to move material into and out of the path of the particle beam to change the energy of the particle beam, and thus the depth at which the particle beam will penetrate the irradiation target.

[0106] Figure 5 and Figure 6 A diagram of an example scanning magnet 108 is shown. The scanning magnet 108 includes two coils 111 that control movement of the particle beam in the X direction, and two coils 112 that control movement of the particle beam in the Y direction. In some embodiments, control is achieved by changing the current through one or both sets of coils to thereby change the magnetic field(s) generated thereby. By appropriately changing the magnetic field(s), the particle beam can be moved in the X direction and / or the Y direction across the irradiation target. In some embodiments, the scanning magnet is not physically moveable relative to the particle accelerator. In other embodiments, the scanning magnet can be moveable relative to the accelerator (e.g., in addition to movement provided by a gantry). In some embodiments, the scanning magnet can be controllable to move the particle beam continuously. In other embodiments, the scanning magnet is controllable at intervals or at specific times. In some embodiments, there can be different scanning magnets to control movement of the beam in the X direction and / or the Y direction. In some embodiments, there can be different scanning magnets to control portions of the movement of the beam in the X direction and / or the Y direction.

[0107] In some embodiments, the ion chamber 109 detects the dose applied by the particle beam by detecting the number of ion pairs generated within the gas caused by the incident radiation. The number of ion pairs corresponds to the dose provided by the particle beam. This information is fed back to a computer system that controls the operation of the particle therapy system. The computer system (not shown), which can include a memory and one or more processing devices, determines whether the dose detected by the ion chamber is the expected dose. If the dose is not as expected, the computer system can control the accelerator to interrupt the generation and / or output of the particle beam, and / or control the scanning magnets to prevent the particle beam from being output to the irradiation target. For example, to prevent or modify the output of the particle beam, the computer system can turn off / turn on the ion source, change the frequency of the RF sweep, activate one or more mechanisms (such as a fast kicker magnet (not shown)) to divert the beam to an absorber material, and thereby prevent the beam from being output, and so on.

[0108] Figure 7 An example embodiment of the energy degrader 110 is shown, which is a range modulator 115. In some embodiments, such as the one shown in FIG. 1, the range modulator includes a series of plates 116. The plates can be made of one or more of the following example materials: polycarbonate, carbon, beryllium, or other low atomic number materials. However, other materials can be used instead of or in addition to these example materials. Figure 7

[0109] One or more of the plates can be moved into or out of the path of the beam, thereby affecting the energy of the particle beam, and thereby affecting the depth of penetration of the particle beam into the irradiation target. For example, the more plates that are moved into the path of the particle beam, the more energy will be absorbed by the plates, and the particle beam will have less energy. Conversely, the fewer plates that are moved into the path of the particle beam, the less energy will be absorbed by the plates, and the particle beam will have more energy. A higher energy particle beam penetrates deeper into the irradiation target than a lower energy particle beam. In this context, "higher" and "lower" are relative terms and do not have any specific numerical meaning.

[0110] The plates are physically moved into and out of the path of the particle beam. For example, as shown in FIG. 1, the plates are moved by a motor 117. The motor 117 can be controlled by the computer system to move the plates into and out of the path of the particle beam. Figure 8 ​As shown, the plates 116a move along the direction of the arrows 117 between positions in the path of the particle beam and positions out of the path of the particle beam. The plates are computer controlled. In general, the number of plates that move into the path of the particle beam corresponds to the depth at which a scan of the irradiation target occurs. For example, the irradiation target can be divided into sections, each corresponding to an irradiation depth. One or more plates of the range modulator can move into or out of the beam path to the irradiation target in order to achieve the appropriate energy to irradiate each of these sections of the irradiation target. Conventionally, the range modulator is stationary relative to the particle beam during a scan of a portion (e.g., a section) of the irradiation target, except for its plates moving into and out of the path of the particle beam.

[0111] In some embodiments, Figure 7 and Figure 8 The range modulator of that can be replaced with a range modulator that tracks the movement of the particle beam at least some of the time. This type of energy degrader is described in more detail below. In some embodiments, the range modulator can be an energy switching range modulator, relative to Figures 35 to 49 Examples of which are described.

[0112] In some embodiments, the particle accelerator can be an energy variable particle accelerator, such as the example particle accelerators described in U.S. Patent Application No. 13 / 916,401, filed June 12, 2013 (U.S. Patent Publication No. 2014 / 0371511), the contents of which are incorporated by reference herein. In example systems that use an energy variable particle accelerator, there can be less need for an energy degrader of the type described herein, as the energy level of the particle beam can be controlled by the particle accelerator. For example, in some systems that employ an energy variable particle accelerator, no energy degrader can be used. In some systems that employ an energy variable particle accelerator, an energy degrader can still be used to vary the beam energy level.

[0113] In some embodiments, a treatment plan is established prior to treating the irradiation target. The treatment plan can specify how a particular irradiation target is to be scanned. In some embodiments, the treatment plan specifies the following information: the type of scan (e.g., spot scan or raster scan); the scan locations (e.g., the locations of the spots to be scanned); the magnet current for each scan location; the dose, spot size for each spot; the location (e.g., depth) of the sections of the irradiation target; the particle beam energy for each section; the plates or other types of pieces to move into the beam path for each particle beam energy; and so on. In general, a spot scan involves applying irradiation at discrete spots on the irradiation target, and a raster scan involves moving a radiation spot across the irradiation target. The concept of spot size thus applies to both raster scans and spot scans.

[0114] In some embodiments, the overall treatment plan for irradiating the target includes different treatment plans for different cross-sections of the irradiation target. The treatment plans for different cross-sections can contain the same information or different information, such as the information provided above.

[0115] In some embodiments, the scanning system can include a collimator 120 Figure 3 ), to collimate the particle beam, which can include an aperture that can be disposed relative to the irradiation target to limit the extent of the particle beam and thereby change the shape of the spot applied to the irradiation target. For example, the collimator can be disposed downstream of the beam path of the energy degrader and before the particle beam hits the irradiation target. The collimator can contain an area through which the particle beam passes (e.g., a hole or a transmissive material), and another material (e.g., brass) around the hole that inhibits or prevents passage of the particle beam.

[0116] In some embodiments, the collimator can include a structure that defines an edge. The structure can include a material that inhibits transmission of the particle beam, such as brass. The structure can be controllable to move in two dimensions relative to the irradiation target so that at least a portion of the structure is between at least a portion of the particle beam and the irradiation target. For example, the structure can be movable in an X direction and a Y direction of a plane that intersects the particle beam and that is parallel or substantially parallel to the cross-section of the irradiation target being treated. Using a collimator in this way can be advantageous because it can be used to tailor the cross-sectional shape of the particle beam that reaches the patient, thereby limiting the amount of particle beam that extends beyond the irradiation target. For example, as shown in FIG. 22, the structure 220 in the collimator prevents portions 221 of the particle beam 222 from reaching the target 224, thereby limiting the beam that goes to the irradiation target and reducing exposure of healthy tissue 225 to radiation. By placing a structure with an edge between portions of the particle beam and the patient, the example collimator also provides a limited, or sharp, edge to the portions of the particle beam that reach the patient, thereby facilitating more precise dose application. Figure 9

[0117] The positioning and movement of the collimator can be controlled by a control computer system that controls other features of the particle therapy system described herein. For example, the collimator can be controlled according to the treatment plan to track (e.g., follow) movement of the particle beam across at least a portion of the irradiation target. In some embodiments, the collimator is controlled to track the entire movement of the particle beam relative to the irradiation target. For example, in some embodiments, the collimator can be controlled to track movement of the particle beam throughout the entirety of the irradiation target, for example, both at the edges of the irradiation target and inside the irradiation target. In some embodiments, the collimator is controlled to track only some movement of the particle beam relative to the irradiation target. For example, the collimator can be controlled to track movement of the particle beam relative to the irradiation target only when the particle beam reaches the edges of the irradiation target. ​

[0118] With reference to Figure 10 As an example, the particle beam can follow a path in the irradiation target 229, as indicated by arrow line 230. The collimator 231 can not track movement of the particle beam inside 233 of the irradiation target 229. However, the collimator 231 can track only movement of the particle beam along the edge of the irradiation target, e.g., roughly along arrow 232. For example, each time the particle beam reaches the edge 234 of the irradiation target, the collimator can move, or can have moved previously, to intercept the particle beam at the edge and thereby limit exposure of surrounding tissue 235 to the beam. When and how much the collimator moves can depend on the size of the particle beam cross-section (spot) and the speed of the particle beam scan. In this example, there is no need to limit exposure to the particle beam in the interior of the irradiation target; thus, the collimator need not track the beam in the interior.

[0119] The movement of the collimator can be controlled in various ways. For example, the current through the magnet 108 can correspond to the deflection of the particle beam by the magnet, and thereby to the position of the particle beam spot on the irradiation target. Thus, for example, knowing the current through the magnet and the position of the irradiation target relative to the magnet, a computer system controlling operation of the scanning system can determine the projected position of the irradiation spot. And, knowing the position of the irradiation spot, the computer system can control the scanning system, particularly the collimator, to track movement of all or part of the movement of the irradiation spot as it moves, as described herein. In some embodiments, the computer system can control the scanning system, particularly the collimator, so that the collimator reaches a position before the particle beam spot reaches that position, as described in more detail below.

[0120] Using a collimator, such as the ones described above, can have advantages. For example, in some cases, a particle beam scanned target can include achieving precision and uniformity of dose at the edge of the irradiation target or coverage in the interior of the irradiation target. Using a collimator, these goals can be further aided by allowing a relatively large particle beam spot to be used for scanning. In this context, a spot size can be considered "large" if the area of the spot size is within a specified percentage of the area of the irradiation target. This percentage can typically be 2.5%, but values between, for example, 0.25% and 25% can also be used. Scanning using a relatively large spot size increases the fractional area coverage of the irradiation target per beam pulse. Typically, the larger the spot size, the less the target uniformity is adversely affected by target (patient) motion. However, at the edge, the collimator reduces the chance that radiation from the large spot impacts tissue outside the irradiation target (e.g., healthy tissue) by shrinking the lateral penumbra. Traditionally, smaller spot sizes are preferred because they allow more precise dose at the edge compared to larger spot sizes. However, these smaller spot sizes can result in slower treatment times for a given treatment volume, and reduced edge conformality due to reduced edge resolution and increased penumbra, compared to the edges of the collimation.

[0121] The collimator can have any number of different shapes or configurations, and can or can not include one or more moving parts. In exemplary embodiments, the collimator is composed of brass and / or other radiation blocking materials, and has a thickness on the order of several centimeters. However, different collimators can have different compositions and thicknesses.

[0122] In exemplary embodiments, the collimator is a structure having one or more edges that are limited. For example, the collimator can be a structure that contains an aperture or hole. Figure 11 An example of this type of collimator 239 is shown. The collimator 239 can have any appropriate shape, with an aperture therein. The edges of the aperture can be used to limit the application of the particle beam, for example as shown in Figure 9 The aperture can edit all or part of the tracking of the particle beam for the scanning operation. For example, the aperture can track the movement of the particle beam only at the edge of the irradiation target or throughout the entire movement of the beam. That is, the collimator itself can move along the edge of the irradiation target to track the movement of the particle beam (e.g., so that the position of the collimator coincides with the particle beam when the particle beam reaches the edge of the irradiation target).

[0123] In some implementations, the collimator may include two or more apertures that are controlled to overlap and thus achieve a specific size. For example, as Figure 12 As shown, orifices 244 and 245 are parts of the corresponding structures 246 and 247. The structures move relative to each other, as... Figure 13 As shown, this causes the apertures 244 and 245 to overlap and change size, and in some cases, the shape of the resulting aperture 248 is changed to allow the particle beam to pass through the aperture 248. Shapes other than those shown can be used.

[0124] In some embodiments, the collimator can track the movement of the particle beam as it travels within the irradiated target. For example, in some embodiments, the diameter of the aperture may be smaller than the diameter of the particle beam spot. In some systems, it may be desirable to use a spot with a specific diameter across the entire irradiation location (including locations within the irradiated target). Therefore, in these systems, the aperture can track the entire movement of the particle beam spot, thereby achieving an appropriate particle beam spot diameter for treatment. In some embodiments, the aperture of the collimator can vary in size and / or shape. For example, the collimator may have one or more movable portions to change the size and shape of the aperture (e.g., reduce its diameter, surface area, etc.).

[0125] In an exemplary embodiment, the collimator may be a structure having one or more straight edges. For example, the collimator may comprise a square, rectangular, or substantially linear structure, each having at least one edge that can be positioned in the path of the particle beam.

[0126] In an exemplary embodiment employing straight edges, the collimator may have a multi-leaf structure, such as... Figure 14 In. Figure 14 In this configuration, collimator 250 tracks movement along the edge of the irradiated target 251. Fingers 252 move up or down, or toward or away from the irradiated target, to achieve an edge shape 253 that substantially matches the edge shape of the irradiated target and blocks the particle beam from reaching healthy tissue (or tissue that should not be irradiated). For example, each finger may move up or down, or extend and retract, or a combination of such movements, to substantially match the edge shape. Collimator 250 itself may move along the edge of the irradiated target 251 (e.g., roughly in the direction of arrow 255) to track the movement of the particle beam (e.g., such that the collimator's position coincides with the particle beam when the particle beam reaches the edge of the irradiated target). In some embodiments, collimator 250 may or may not move into the interior of the irradiated target during scanning operations.

[0127] Conventional multi-leaf collimators are stationary relative to the irradiated target and comprise two sets of fingers that face each other and move relative to each other to achieve proper collimation. Such collimators can contain tens, hundreds, or even thousands of fingers, and their size can be as large as the irradiation field itself. In some embodiments, the irradiation field can be defined by a plane angled to the beam, defining the maximum range of movement of the particle beam relative to the irradiated target in the X and Y directions. However, in the exemplary embodiments described herein, the collimator moves relative to the irradiated target (e.g., tracing or moving along the edge of the irradiated target) and only requires providing a limited edge at a point on the irradiated target, indicating where and when the spot hits that point. Accordingly, multi-leaf collimators can be manufactured to be significantly smaller than their conventional counterparts. For example, the multi-leaf collimator described herein can contain ten or fewer (e.g., two, three, four, five, six, seven, eight, or nine) fingers (or more, if desired).

[0128] In an exemplary implementation that employs straight edges, such as Figure 15 As shown, collimator 260 may be rectangular in shape and move along the edge of irradiated target 261. Collimator 260 may move along the edge of irradiated target to track the movement of the particle beam (e.g., such that the position of the collimator coincides with the particle beam when the particle beam reaches the edge of irradiated target). During movement along the edge of irradiated target, collimator 260 may also rotate in two or three dimensions, for example, in the XY dimension of arrow 262 and in the Z dimension. This rotation allows at least a portion of the edge of collimator 260 to relatively closely match the edge of irradiated target. Thus, collimator 260 can be appropriately positioned such that when the particle beam reaches the edge of irradiated target, the collimator blocks tissue extending beyond the edge. Therefore, the collimator provides a restricted radiation edge relative to the irradiated target and protects adjacent tissue from the particle beam. The movement of the collimator to the appropriate point on the edge of irradiated target may coincide with the movement of the particle beam or precede the movement of the particle beam.

[0129] In some implementations, the collimator may comprise a single structure having one or more straight edges, such as Figure 15 As shown in the diagram. In other embodiments, the collimator may include two or more such structures at different (e.g., opposite) edges of the irradiated target, such as... Figure 16The collimator comprises two structures 265, 266. Each of the structures 265 and 266 tracks the movement of the particle beam. That is, the structure 265 moves so that its position coincides with the particle beam when the particle beam reaches the edge 269 of the irradiation target, and the structure 266 moves so that its position coincides with the particle beam when the particle beam reaches the edge 270 of the irradiation target. The movement of each structure to the appropriate point on the edge of the irradiation target can coincide with the movement of the particle beam, or precede the movement of the particle beam. For example, the structure 266 can move as the spot scans in the direction of arrow 271 so that the structure 266 is in the appropriate position when the spot returns to the edge 270; and the structure 265 can move as the spot scans in the direction of arrow 272 so that the structure 265 is in the appropriate position when the spot returns to the edge 269. The structures 265 and 266 can move simultaneously, at different times, or there can be overlap in their times of movement. This type of arrangement allows the particle beam to move from edge to edge of the irradiation target, and the collimator allows for a limited field of irradiation at both edges. Also, because the collimator is made up of multiple structures, the scanning does not need to be slowed down significantly to wait for movement of the collimator. In some embodiments, the collimator can comprise more than two (e.g., three, four, etc.) structures of the type and operation shown in FIG. 27. In some embodiments, the two or more structures making up the collimator can be structures comprising holes, such as the structures shown in FIG. 28. Otherwise, the operation of the double-structure collimator is as described above. Figure 16 In some embodiments, the collimator need not have straight edges, but rather its edge(s) can be curved, as shown in FIG. 29. The collimator can comprise only one such structure or two or more such structures. In some embodiments, the two or more structures making up the collimator can be structures comprising curved edges. For example, two structures of the type shown in FIG. 30 can replace the structure of FIG. 28. Otherwise, the operation of the double-structure collimator is as described above. Figure 11

[0130] In some embodiments, the collimator need not have straight edges, but rather its edge(s) can be curved, as shown in FIG. 29. The collimator can comprise only one such structure or two or more such structures. In some embodiments, the two or more structures making up the collimator can be structures comprising curved edges. For example, two structures of the type shown in FIG. 30 can replace the structure of FIG. 28. Otherwise, the operation of the double-structure collimator is as described above. Figure 17 Figure 17 In some embodiments, the collimator need not have straight edges, but rather its edge(s) can be curved, as shown in FIG. 29. The collimator can comprise only one such structure or two or more such structures. In some embodiments, the two or more structures making up the collimator can be structures comprising curved edges. For example, two structures of the type shown in FIG. 30 can replace the structure of FIG. 28. Otherwise, the operation of the double-structure collimator is as described above. Figure 16

[0131] ​​​In this regard, in example embodiments, the collimator can be a structure having a curvilinear shape with a radius of curvature that varies continuously along its edges, allowing at least portions of the edges to closely match the edges of the irradiation target, either directly or by rotating the edges at an appropriate angle. In this example, the collimator 275 is a cloud-shaped curve, which can be moved to track the beam in part or in whole, and can be rotated in two or three dimensions relative to the irradiation target to control the application of the particle beam. Any suitably curvilinear structure can be included in the collimator. As in the above case, the collimator 275 can be moved only along the edges of the irradiation target to track the movement of the particle beam (e.g., so that the position of the collimator coincides with the particle beam when the particle beam reaches the edge of the irradiation target). As in the above case, the collimator can or can not track the movement of the particle beam inside the irradiation target.

[0132] The collimator can include only one structure of the type shown in Figure 17 , or the collimator can include two or more such structures. For example, Figure 17 two structures of the type shown in Figure 16 may be substituted for the two structures of . Otherwise, the operation of a double-structure collimator is as described above.

[0133] In some embodiments, the treatment planning system can be designed so that the scan speed (e.g., the rate at which the particle beam spot traverses the irradiation target) is different at the edges of the irradiation target than inside the irradiation target. For example, the scan speed can be faster inside the irradiation target than at the edges of the irradiation target. This arrangement allows for more precise scanning at the edges of the irradiation target than inside the irradiation target. This type of variable speed scanning can be implemented using any suitable type of collimator, including those described herein, or it can be implemented without any collimator. In any case, the slower speed at the edges of the irradiation target can allow for more precise scanning there, and can reduce the chance that the particle beam will affect volumes outside the irradiation target.

[0134] In some embodiments, the collimators described herein can be used in intensity modulated proton therapy procedures. In such procedures, the proton beam is projected at the irradiation target from different directions, so that a percentage of the total dose is delivered from each direction. As a result, the amount of dose delivered to volumes outside the irradiation target can be reduced. For example, Figure 18Particle beams 280 are shown being applied to irradiation target 281 from three different angles. In this example, 1 / 3 of the total dose can be applied from one angle; 1 / 3 of the total dose can be applied from another angle; and, 1 / 3 of the total dose can be applied from yet another angle. That is, the particle beam can be scanned at angle 282 relative to horizontal 285 to apply 1 / 3 of the dose; the particle beam can be scanned at angle 283 to apply 1 / 3 of the dose; and, the particle beam can be scanned at angle 284 to apply 1 / 3 of the dose. Thus, the amount of radiation applied to surrounding tissue 287 is spread out at appropriate angles, reducing the chance that the surrounding tissue will be exposed to a harmful amount of radiation. Any appropriate number of angles and appropriate doses for each angle can be employed.

[0135] Irradiation targets, such as tumors, are typically not symmetrical. Accordingly, different angles of application of the particle beam typically require different beam collimation. The example collimators described herein can be positioned at appropriate locations along the edge of the irradiation target (as described above) to provide appropriate collimation for irradiation at a given angle. In some embodiments, the example collimators can track movement of the particle beam, or only some portion (e.g., all) of the movement of the particle beam across the edge of the irradiation target or at all of the angles of application.

[0136] In some embodiments, the example collimators described herein prevent transmission of the particle beam to surrounding tissue by blocking the particle beam. In some embodiments, the example collimators can allow transmission of a portion of the particle beam, resulting in lower levels of radiation being applied to surrounding tissue than the irradiation target. Any of the example collimators described herein can be made in this way.

[0137] The example collimators described herein can be mounted to one or more computer-controlled robotic arms or other structures to control their movement relative to the irradiation target. The collimator can also be mounted to the scanning system itself. Typically, the collimator is mounted closest to the patient relative to other elements of the particle beam scanning system (e.g., downstream of the beam from other elements of the scanning system). In embodiments where the collimator comprises more than one piece (e.g., Figure 16 In some embodiments, a single robotic arm can be configured to independently control different pieces of the collimator, or combinations of pre-assembled pieces.

[0138] In some embodiments, the energy degrader can also be configured to track movement of the particle beam. In this regard, in some embodiments, such as relative to Figure 7 and Figure 8The exemplary embodiments described, the energy degrader can include a plurality of plates that are movable into the path of the particle beam to control the amount of energy in the beam and, thus, the depth of penetration of the particle beam into the irradiation target. In this way, the energy degrader is used to perform a depth (directional or Z-directional) scan in the irradiation target. Typically, each plate absorbs a certain amount of energy in the particle beam. Accordingly, the more plates that are placed in front of the particle beam, the less energy the beam has and the shallower the beam will penetrate into the irradiation target. Conversely, the fewer plates that are placed in front of the particle beam, the more energy the beam has (because less energy is absorbed by the plate(s)) and the deeper the beam will penetrate into the irradiation target. In some embodiments, each plate has about the same thickness and, thus, absorbs about the same amount of beam energy. In other embodiments, different plates can have different thicknesses, with the thickness of the plate corresponding to the amount of energy absorbed by the plate.

[0139] In some embodiments, the plates each have a surface area that is about the size of the irradiation field. In this context, the irradiation field can be defined by a plane that defines the maximum range that the particle beam can move in the X and Y directions relative to the irradiation target. For example, Figure 19 An irradiation field 290 (also referred to as a beam field or irradiation field) in front of an irradiation target 291 is shown. Due to physical system limitations, the particle beam can move across the plane that defines the irradiation field, but cannot move beyond the plane that defines the irradiation field. Accordingly, to ensure that the energy degrader can be applied to any location within the irradiation field, in some embodiments, the plates in the energy degrader each have a surface area that is at least as large as (and in some cases, larger than) the size of the irradiation field. However, this configuration can result in the plates being large (e.g., possibly a square meter or several square meters) and, thus, heavy and relatively slow to move. Slow movement of the plates can result in slower treatment.

[0140] In some embodiments, the energy degrader can be smaller than the size of the irradiation field and track at least part of the movement of the particle beam. Thus, the energy degrader can be lighter, which can reduce the time used to position the energy degrader plates in the path of the particle beam and, thus, reduce treatment time. The energy degrader can track the particle beam in two directions (e.g., XY) or in three directions (e.g., XYZ). That is, the energy degrader can move in a plane perpendicular to the particle beam or the energy degrader can move in a plane perpendicular to the particle beam and along the longitudinal direction of the particle beam. In this regard, any of the collimators described herein can also move in a plane perpendicular to the particle beam or any of the collimators described herein can also move in a plane perpendicular to the particle beam and along the longitudinal direction of the particle beam. The movement of the collimator(s) and the energy degrader(s) can be independent or coordinated.

[0141] For example, the energy degrader can be composed of multiple pieces, which can be plates or other structures configured to absorb particle beam energy during treatment. Each piece can have the same area (XY) and thickness (Z), or different pieces can have different areas and thicknesses. Referring to Figure 20 Two or more pieces 294 with the same or different thicknesses can be placed in the path of the particle beam 293 in front of the irradiation target 295 to achieve a particular amount of energy absorption. Alternatively, a single piece with a particular thickness can be placed in front of the beam to achieve a particular amount of energy absorption. For example, if a particular energy absorption is needed, the control computer can select a piece with an appropriate thickness to achieve that absorption.

[0142] In examples where two or more pieces are placed in front of the beam, the pieces can be assembled prior to placement or dynamically assembled during placement. For example, the control computer can select two pieces, arrange them, and then move the combination of the two pieces into the beam path. Alternatively, the control computer can select two pieces and then move the combination of the two pieces into the beam path simultaneously but not in combination (e.g., each can be moved with a separate robotic arm).

[0143] The energy degrader or its pieces can track movement of the particle beam across at least a portion of the irradiation field, thereby achieving appropriate energy absorption and, thus, beam depth penetration at points on the irradiation target. The treatment plan can specify where the energy degrader needs to be at particular times during treatment, and feedback from ionization at the ion chamber can be used for positioning and positioning corrections, if necessary. In some embodiments, the precision with which the energy degrader needs to track the particle beam is based on the size of the degrader and the spot size of the particle beam at the point where the particle beam intersects the energy degrader.

[0144] More specifically, in some examples, the smaller the surface area of the energy degrader, the more closely the movement of the energy degrader should track the movement of the particle beam. Conversely, in other examples, the larger the surface area of the energy degrader, the less closely the movement of the energy degrader needs to track the movement of the particle beam. For example, referring to Figure 21If the surface area of the energy degrader 299 is close to the surface area of the spot 300 at the point where the particle beam intersects the energy degrader, the energy degrader should track the movement of the particle beam fairly closely in order to ensure that the energy degrader is in front of the particle beam at the appropriate time during treatment relative to the irradiation target 301. For example, the movement of the particle beam 304 from position 302 to position 303 would also require the energy degrader 299 to move in the direction of arrow 305 to remain in the beam path, as the spot and degrader areas are relatively close in size. As noted, the movement of the particle beam can be specified by the treatment plan, and detected using ionization probes at the ion chamber, and fed back to the control computer. This information can also be used to control the movement of the energy degrader.

[0145] In some embodiments, the moveable energy degrader can be significantly larger than the particle beam spot. In these cases, the energy degrader does not need to track the movement of the particle beam as closely to ensure that the energy degrader is in front of the particle beam at the appropriate time during treatment. In fact, depending on the size of the energy degrader, the energy degrader does not need to move at all in some cases of particle beam movement. That is, for some movements of the particle beam, the energy degrader can remain stationary, but for other movements of the particle beam, the energy degrader also moves to intercept the particle beam. For example, Figure 22 An example is shown where the energy degrader 310 is significantly larger than the particle beam spot 311 at the point where the particle beam intersects the energy degrader. As the particle beam spot moves from point 314a to point 314b, the energy degrader remains in the beam path even though the energy degrader has not moved. The control computer system, knowing the size of the degrader and the two spot positions, does not move the energy degrader in this case. Accordingly, in this case, the energy degrader does not need to track the movement of the particle beam spot. However, when the spot moves to point 314c, the energy degrader (or part(s) thereof) will move to track and intercept the beam to remain in the beam path. Accordingly, the size of the energy degrader relative to the beam spot is a factor in determining when and how much the energy degrader moves during scanning.

[0146] In some embodiments, the energy degrader can include multiple portions or parts. For example, one portion or part can be used to track the movement of the particle beam across one portion of the irradiation target (e.g., irradiation applied from the top of the irradiation target), and other portions or parts can be used to track the movement of the particle beam across another portion of the irradiation target (e.g., irradiation applied from the bottom of the target).

[0147] The energy degrader (or a piece thereof) can have any shape, e.g., square, rectangular, circular, oval, irregular, regular, polygonal, spherical, cubic, tetrahedral, etc. The energy degrader (or a piece thereof) can have any suitable size. For example, the surface area of the energy degrader (or a piece thereof) can be less than the area of the irradiation field, less than 3 / 4 of the area of the irradiation field, less than 1 / 2 of the area of the irradiation field, less than 1 / 3 of the area of the irradiation field, less than 1 / 4 of the area of the irradiation field, less than 1 / 5 of the area of the irradiation field, etc. The surface area of the energy degrader (or a piece thereof) can be less than twenty times the area of a particle beam spot at the irradiation field, less than fifteen times the area of a particle beam spot at the irradiation field, less than ten times the area of a particle beam spot at the irradiation field, less than nine times the area of a particle beam spot at the irradiation field, less than eight times the area of a particle beam spot at the irradiation field, less than seven times the area of a particle beam spot at the irradiation field, less than six times the area of a particle beam spot at the irradiation field, less than five times the area of a particle beam spot at the irradiation field, less than four times the area of a particle beam spot at the irradiation field, less than three times the area of a particle beam spot at the irradiation field, or less than two times the area of a particle beam spot at the irradiation field. In some embodiments, the surface area of the energy degrader (or a piece thereof) can be a multiple of the spot size, e.g., two times the spot size, three times the spot size, five times the spot size, ten times the spot size, etc.

[0148] In some embodiments, each piece (e.g., layer in a multi-layer) has the same size, shape, thickness, and composition. In other embodiments, different pieces can have different sizes, shapes, thicknesses, and compositions.

[0149] The movement of the example energy degraders described herein can be controlled in various ways. For example, the current through the magnet 108 can correspond to the deflection of the particle beam by the magnet, and thus, to the position of the particle beam spot on the irradiation target. Thus, for example, knowing the current through the magnet and the position of the irradiation target relative to the magnet, a computer system controlling the operation of the scanning system can determine the projected position of the irradiation spot. And, knowing the position of the irradiation spot, and the size of the energy degrader relative to the spot size, the computer system can control the energy degrader to track, if necessary, the movement of all or part of the irradiation spot as it moves, as described herein.

[0150] The example movable energy degraders described herein can be mounted to one or more computer-controlled robotic arms or other structures that also contain elements of the scanning system to control movement relative to the irradiation target. In embodiments in which the energy degrader comprises more than one piece (e.g., multiple pieces or plates), there can be more than one robotic arm to independently control the pieces of the different energy degraders according to the treatment plan. In some embodiments, a single robotic arm can be configured to control the different pieces independently.

[0151] Different cross sections of the irradiation target can be scanned according to different treatment plans. As described above, the energy degrader is used to control the depth of scanning. In some embodiments, the particle beam can be interrupted or redirected during configuration of the energy degrader. In other embodiments, this is not necessarily the case.

[0152] Described herein are examples of treatment cross sections of an irradiation target. These can be cross sections that are roughly perpendicular to the direction of the particle beam. However, the concepts described herein are equally applicable to handling other portions of the irradiation target that are not cross sections perpendicular to the direction of the particle beam. For example, the irradiation target can be divided into volumes that are spherical, cubical, or other shapes, and these volumes can be treated using the example processes, systems, and / or apparatuses described herein.

[0153] The processes described herein can be used with a single particle accelerator, and any two or more features thereof described herein can be used with a single particle accelerator. The particle accelerator can be used in any type of medical or non-medical application. Examples of particle therapy systems that can be used are provided below. Notably, the concepts described herein can be used in other systems not specifically described.

[0154] Referring to Figure 23 , an example embodiment of a charged particle radiation therapy system 401 includes a particle accelerator 402 that produces a beam, the particle accelerator 402 being small enough in weight and size to allow it to be mounted on a rotating gantry 404, and its output to be directed straight (i.e., substantially directly) from the accelerator housing toward a patient 406. The particle accelerator 402 also includes a scanning system of the type described herein, which can operate as described with respect to Figures 3 to 22 and Figures 34 to 49 .

[0155] In some embodiments, the steel gantry has two feet 408, 410 mounted for rotation on two respective bearings 412, 414, the bearings 412, 414 being located on opposite sides of the patient. The accelerator is supported by a steel truss 416 that is long enough to span a treatment area 418 in which the patient lies (e.g., twice as tall as the person to allow the person to rotate fully within the space while the patient's any desired target area remains aligned with the beam), and is stably attached at both ends to the rotating feet of the gantry.

[0156] In some examples, the gantry rotation is limited to a range 420 of less than 360 degrees, for example, about 180 degrees, to allow the floor 422 to extend from the walls of the vault 424 housing the treatment system into the patient treatment area. The limited rotation range of the gantry also reduces the required thickness of some of the walls (which are not directly aligned with the beam, for example, wall 430) that provide radiation shielding for people outside the treatment area. A range of 180 degrees of gantry rotation is sufficient to cover the full treatment access angle, but it can be useful to provide a larger range of travel. For example, the range of rotation can be between 180 and 330 degrees and still provide a gap in the treatment floor space. In other embodiments, the rotation is not limited as described above.

[0157] The horizontal rotation axis 432 of the gantry is nominally located one meter above the floor where the patient and therapist interact with the treatment system. This floor is located about 3 meters above the floor of the treatment system shielded vault. The accelerator can swing below the elevated floor to deliver the treatment beam from below the rotation axis. The patient chair moves and rotates in a substantially horizontal plane parallel to the rotation axis of the gantry. With this configuration, the chair can be rotated through a range 434 of about 270 degrees in the horizontal plane. This combination and freedom of the gantry and patient rotation ranges allows the therapist to select almost any access angle for the beam. If desired, the patient can be placed on the chair in the opposite orientation and then all possible angles can be constructed.

[0158] In some embodiments, the accelerator uses a synchrocyclotron configuration with a high-field superconducting magnet structure. Because the bending radius of a charged particle of a given kinetic energy decreases in direct proportion to an increase in the magnetic field applied to it, a high-field superconducting magnet structure allows the accelerator to be made smaller and lighter. A synchrocyclotron uses a magnetic field that is non-uniform over the angle of rotation and decreases in strength as the radius increases. Such a field shape can be achieved regardless of the strength of the magnetic field, so there is, in theory, no upper limit to the strength of the magnetic field (and hence the energy of the particles resulting from a fixed radius) that can be used in a synchrocyclotron.

[0159] The synchrocyclotron is supported on a gantry so that the generated beam is directly aligned with the patient. The gantry allows the synchrocyclotron to be rotated about a horizontal rotation axis that contains a point (isocenter point 440) within or near the patient. Split trusses parallel to the rotation axis support the synchrocyclotron on both sides.

[0160] Because the range of gantry rotation is limited in some example embodiments, the patient support area can be contained within a wide area about the isocenter. Because the floor can extend widely about the isocenter, the patient support table can be positioned relative to a vertical axis 442 that passes through the isocenter such that, by a combination of gantry rotation and table movement and rotation, any angle of beam direction into any portion of the patient can be achieved. In some embodiments, the two gantry arms are separated by more than twice the height of a tall patient, allowing the chair with the patient to rotate and translate in a horizontal plane above the raised floor.

[0161] Limiting the angle of gantry rotation allows for a reduction in the thickness of at least one of the walls of the treatment room. Thick walls, typically constructed of concrete, provide radiation protection to individuals outside the treatment room. The thickness of the wall downstream of the stopped proton beam can be about twice the thickness of the wall at the opposite end of the room to provide an equivalent level of protection. The limited range of gantry rotation allows the treatment room to be located below ground on three sides, while allowing the footprint adjacent to the thinnest wall, reducing the cost of constructing the treatment room.

[0162] In the example embodiment shown in Figure 23 , the superconducting synchrocyclotron 402 operates at a peak magnetic field of 8.8 Tesla in the inter-pole gap of the synchrocyclotron. The synchrocyclotron produces a beam of protons with an energy of 250 MeV. In some embodiments, the synchrocyclotron is a variable energy machine and is capable of outputting proton beams with different energies. In some embodiments, the synchrocyclotron can produce a beam with a fixed energy. In some embodiments, the field strength can be in the range of 4T to 20T and the proton energy can be in the range of 150 to 300 MeV.

[0163] The radiation therapy system described in this example is used for proton radiation therapy, but the same principles and details can be applied in a similar system used in a heavy ion (ion) therapy system.

[0164] As shown in Figure 1 , Figure 2 , Figure 24 , Figure 25 and Figure 26 , an example synchrocyclotron 10 (e.g., 402 in Figure 23 ) includes a magnet system 122 containing a particle source 190, a radio frequency drive system 191, and a beam extraction system 138. In this example, the magnetic field established by the magnet system has a shape suitable for maintaining the focus of the contained proton beam using a combination of a split pair of toroidal superconducting coils 140, 142 and a pair of shaped ferromagnetic (e.g., low carbon steel) pole faces 144, 146.

[0165] Two superconducting magnet coils are centered on a common axis 147 and spaced apart along the axis. The coils can be formed from Nb3Sn-based superconducting 0.8 mm diameter stranded wire (initially consisting of a niobium-tin core surrounded by a copper sheath) deployed to the geometry of the cable conductors in the twisted channel. After the seven individual stranded wires are joined together, they are heated to produce a reaction that forms wires of the final (brittle) superconducting material. After the material has reacted, the wires are soldered to the copper channel (outer dimensions 3.18 × 2.54 mm and inner dimensions 2.08 × 2.08 mm) and covered with insulation (in this example, braided fiberglass material). The copper channel containing the wires is then wound into a coil with a rectangular cross-section. The wound coils are then vacuum-impregnated with an epoxy resin compound. The finished coils are mounted on an annular stainless steel reverse bobbin. Heating blankets can be placed at the intervals of the wound layers to protect the assembly in the event of magnet quenching.

[0166] The entire coil can then be covered with a copper sheet to provide thermal conductivity and mechanical stability, and then encapsulated in an epoxy resin layer for additional layers. Pre-compression of the coil can be provided by heating a stainless steel reverse-winding spool and fitting the coil within it. The inner diameter of the reverse-winding spool is chosen such that it remains in contact with the coil and provides some compression when the entire material is cooled to 4K. This can be achieved by heating the stainless steel reverse-winding spool to approximately 50°C and fitting the coil at 100 Kelvin.

[0167] The coil geometry is maintained by mounting the coil in a "reverse" rectangular winding spool 156 to apply a restoring force against the torsional forces generated when the coil is energized. Figure 25 As shown, in some embodiments, a set of warm-to-cold support strips 402, 404, 406 are used to maintain the coil position relative to the corresponding magnet pole pieces and cryostat. Supporting the cold material with thin strips reduces heat leakage applied to the cold material by the rigid support system. The strips are arranged to withstand the changing gravity on the coil as the magnet rotates on the gantry. They withstand the combined effect of gravity and the large centrifugal force generated by the coil when it is disturbed from its perfectly symmetrical position relative to the magnet yoke. Additionally, the links act to reduce the dynamic forces applied to the coil as the gantry accelerates and decelerates as its position changes. Each warm-to-cold support may include an S2 fiberglass link and a carbon fiber link. The carbon fiber link spans the pin support between the warm yoke and the intermediate temperature (50-70K), and the S2 fiberglass link 409 spans the intermediate temperature pin and connects to the pin support of the cold mass. Each pin may be made of high-strength stainless steel.

[0168] refer to Figure 1The field intensity distribution as a function of the radius is generally determined by selecting the coil geometry and the shape of the pole faces; the contours of the pole faces 144 and 146, which are permeable to the yoke material, can fine-tune the shape of the magnetic field to ensure that the particle beam remains focused during acceleration.

[0169] By enclosing the coil assembly (coil and winder) within a vacuum-sealed toroidal aluminum or stainless steel cryogenic chamber 170 (cryostat), the superconducting coil is maintained at a temperature close to absolute zero (e.g., approximately 4 Kelvin). The cryogenic chamber 170 provides free space for the coil winding structure, except for a restricted set of support points 171, 173. In alternative versions (e.g., Figure 2 In this process, the outer wall of the cryogenic device can be made of low-carbon steel to provide an additional return flux path for the magnetic field.

[0170] In some embodiments, a single-stage Gifford-McMahon cryocooler and three two-stage Gifford-McMahon cryocoolers are used to achieve and maintain temperatures close to absolute zero. Each two-stage cryocooler has a second-stage cold end attached to a condenser that re-condenses helium vapor into liquid helium. In some embodiments, a cooling channel containing liquid helium (not shown) is used to achieve and maintain temperatures close to absolute zero. This cooling channel is formed within a superconducting coil support structure (e.g., a reverse-winding bobbin) and contains a thermal connection between the liquid helium in the channel and the corresponding superconducting coil.

[0171] In some embodiments, the coil assembly and the constant-low temperature chamber are housed and completely enclosed within the two halves 181, 183 of a cartridge-shaped magnet yoke 100. The yoke 100 provides a path for the return magnetic flux 184 and a magnetically shielded volume 186 between the pole faces 144, 146 to prevent external magnetic influences from interfering with the shape of the magnetic field within this volume. The yoke also serves to reduce stray magnetic fields near the accelerator. In other embodiments, the coil assembly and the constant-low temperature chamber are housed and completely enclosed within a non-magnetic enclosure, and an active return system is used to provide a path for the return magnetic flux, examples of which are described above.

[0172] like Figure 1 and Figure 27 As shown, the synchrotron accelerator includes a particle source 190 of a Penning ion meter, which is geometrically located near the geometric center 192 of the magnet structure 182. The particle source can be as described below, or the particle source can be of the type described in U.S. Patent Application No. 11 / 948,662 (U.S. Patent No. 8,581,523), which is incorporated herein by reference.

[0173] Particle source 190 supplies hydrogen from hydrogen supply section 399 through gas lines 393 and 394 for delivering gaseous hydrogen. Cable 294 carries current from current source to excite electron discharge from cathodes 392, 390 aligned with magnetic field 400.

[0174] In this example, the electrons discharged from the gas exiting tube 394 through the orifice are ionized to produce a supply of cations (protons) for acceleration by a semi-circular (D-shaped) radio frequency plate and a dummy D-shaped plate, the semi-circular radio frequency plate spanning half of the space enclosed by the magnet structure. In the case of an interrupted particle source (examples of which are described in U.S. Patent Application No. 11 / 948,662), all (or a considerable portion, e.g., most) of the tube containing the plasma is removed from the acceleration region.

[0175] like Figure 28 As shown, the D-shaped plate 500 is a hollow metal structure with two semi-circular surfaces 503, 505 enclosing a space 507 in which protons are accelerated during half of their rotation around the space enclosed by the magnetic structure. A conduit 509 opening into space 507 extends through the outer shell (e.g., a yoke or pole piece(s)) to an external location from which a vacuum pump can be attached to the vacuum space 507 and the remaining space within the vacuum chamber where acceleration occurs. A dummy D-shape 502 comprises rectangular metal rings spaced close to the exposed edges of the D-shaped plate. The dummy D-shape is grounded to the vacuum chamber and the magnetic yoke. The D-shaped plate 500 is driven by a radio frequency (RF) signal applied at the end of an RF transmission line to influence the electric field in space 507. As the accelerated particle beam increases in distance from the geometric center, the RF electric field varies over time. The radio frequency electric field can be controlled in a manner described in U.S. Patent Application No. 11 / 948,359 (U.S. Patent No. 8,933,650), entitled “Matching A Resonant Frequency Of A Resonant Cavity To A Frequency Of An Input Voltage,” the contents of which are incorporated herein by reference.

[0176] For a beam emitted from a centrally located particle source, a large voltage difference can be applied across the RF plate to clear the particle source structure as it begins to spiral outward. 20,000 volts are applied across the RF plate. In some versions, 8,000 to 20,000 volts can be applied across the RF plate. To reduce the power required to drive this large voltage, the magnet structure is arranged to reduce the capacitance between the RF plate and ground. This is accomplished by forming holes with sufficient clearance through the RF structure, passing through the outer yoke and the cryostat housing, and creating sufficient space between the magnet pole faces.

[0177] The high voltage AC potential of the D-plates is swept downward in frequency during the acceleration cycle to account for the relativistic mass increase of the protons and the magnetic field decrease. The dummy D-plate does not require a hollow semi-cylindrical structure as it is at ground potential with the vacuum chamber walls. Other plate arrangements can be used, such as more than one pair of acceleration electrodes driven at different electrical phases or multiples of the fundamental frequency. By using, for example, a rotating capacitor with intermeshing rotating and stationary vanes, the RF structure can be tuned to maintain a high Q during the desired frequency sweep. During each meshing of the vanes, the capacitance is increased, thereby lowering the resonant frequency of the RF structure. The vanes can be shaped to produce the precise frequency sweep desired. The drive motor for the rotating condenser can be phase locked to the RF generator for precise control. During each meshing of the vanes of the rotating condenser, a beam of particles can be accelerated.

[0178] The vacuum chamber in which acceleration occurs is a generally cylindrical container that is thin at the center and thick at the edges. The vacuum chamber encloses the RF plates and the particle source and is evacuated by a vacuum pump. Maintaining a high vacuum can reduce the likelihood of the accelerated ions losing energy by colliding with gas molecules and allows the RF voltage to be maintained at a high level without arcing to ground.

[0179] The protons (or other ions) traverse a generally helical orbital path beginning at the particle source. In each half of each loop of the helical path, the protons gain energy as they pass through the RF electric field. As the protons gain energy, the radius of the central orbit of each camera of the helical path of the protons is greater than the previous loop, until the loop radius reaches the maximum radius of the pole face. At that location, the magnetic and electric field perturbations direct the protons into an area of rapid magnetic field decrease, and the protons exit the area of high magnetic field and are directed through a vacuum tube (herein referred to as an extraction channel) to exit the synchrocyclotron. A magnetic regenerator can be used to vary the magnetic field perturbation to direct the protons. As the protons enter the area of significantly decreased magnetic field present in the room surrounding the synchrocyclotron, the exiting protons will tend to disperse. Beam shaping elements 607, 609 in the extraction channel 138( Figure 25 ) redirect the protons so that they remain in a straight beam of limited spatial extent.

[0180] As the beam exits the extraction channel, it passes through a beam forming system 525( Figure 25 ), which can include a scanning system of the type described herein. The beam forming system 525 can be used in conjunction with an internal gantry that controls the application of the beam.

[0181] Stray magnetic fields exiting the synchrocyclotron can be shielded by the magnet yokes (which also act as shields) and a separate magnetic shield 514 (e.g. Figure 1The separate magnetic shield includes a layer 517 of ferromagnetic material (e.g., steel or iron) that encloses the pillbox yoke, separated by a space 516. The configuration of the sandwich of yoke, space, and shield achieves adequate shielding of the magnetic field leakage for a given lower weight. As noted above, in some embodiments, an active return system can be used instead of or to augment the operation of the magnetic yoke and shield.

[0182] Referring to Figure 23 , the gantry allows the synchrocyclotron to rotate about a horizontal axis of rotation 432. The truss structure 416 has two generally parallel spans 480, 482. The synchrocyclotron is cradled between the spans, midway between the feet. The gantry is balanced for rotation about the bearings using counterweights 622, 624 mounted on the ends of the feet opposite the truss.

[0183] The gantry is driven in rotation by a motor mounted on one or both of the gantry feet and connected to the bearing housing by a drive gear. The rotational position of the gantry is derived from signals provided by an axle angle encoder integrated into the gantry drive motor and drive gear.

[0184] At the location where the ion beam exits the synchrocyclotron, a beam shaping system 525 acts on the ion beam to impart properties suitable for treatment of the patient. For example, the beam can be spread and its penetration depth varied to provide uniform radiation across a given target volume. The beam shaping system can include active scanning elements as described herein.

[0185] The entire active system of the synchrocyclotron (current driven superconducting coils, RF driven plates, vacuum pumps for the vacuum acceleration ion chamber and for the superconducting coil cooling chamber, current driven particle source, hydrogen gas source, and RF plate coolers, as examples) can be controlled by appropriate synchrocyclotron control electronics (not shown), which can include, for example, one or more processing devices that execute instructions from memory to implement the control.

[0186] As noted above, referring to the system 602 of Figure 29 , the particle accelerator that generates the beam, in this case a synchrocyclotron 604 (which can include any and all features described herein) can be mounted on a rotating gantry 605. The rotating gantry 605 is of the type described herein and can be angularly rotated about a patient support 606. This feature enables the synchrocyclotron 604 to provide the particle beam substantially directly to the patient from a variety of angles. For example, as Figure 29As shown, if the synchrocyclotron 604 is above the patient support 606, the particle beam can be directed downward toward the patient. Alternatively, if the synchrocyclotron 604 is below the patient support 606, the particle beam can be directed upward toward the patient. The particle beam is essentially applied directly to the patient in that no intermediate beam routing mechanism is required. In this context, a routing mechanism is distinguished from a shaping or sizing mechanism in that a shaping or sizing mechanism does not re-route the beam, but rather sizes and / or shapes the beam while leaving the beam on the same overall trajectory.

[0187] The particle accelerator used in the example particle therapy systems and example scanning systems described herein can be a variable energy particle accelerator, examples of which are described below.

[0188] The energy of the extracted particle beam (the particle beam output from the accelerator) can affect the use of the particle beam during treatment. In some machines, the energy of the particle beam (or particles in the particle beam) does not increase after extraction. However, the energy can be decreased based on treatment needs after extraction and before treatment. With reference to Figure 30 , the example treatment system 910 includes an accelerator 912, such as a synchrocyclotron, from which a particle (e.g., proton) beam 914 having variable energy is extracted to irradiate a target volume 924 of a body 922. Optionally, one or more additional devices, such as a scanning unit 916 or a scattering unit 916, one or more monitoring units 918, and an energy degrader 920 are placed along an irradiation direction 928. The devices intercept a cross-section of the extracted beam 914 and change one or more properties of the extracted beam for processing.

[0189] A target volume irradiated by a particle beam for treatment (an irradiation target) typically has a three-dimensional configuration. In some instances, to conduct treatment, the target volume is divided into multiple layers along an irradiation direction of the particle beam so that irradiation can be conducted layer by layer. For certain types of particles (e.g., protons), the penetration depth (or layer reached by the beam) within the target volume is primarily determined by the energy of the particle beam. A particle beam of a given energy does not substantially reach beyond the penetration depth corresponding to that energy. To move the beam irradiation from one layer of the target volume to another layer, the energy of the particle beam is changed.

[0190] In Figure 30In the illustrated example, the target volume 924 is divided into nine layers 926a-926i along the irradiation direction 928. In an example procedure, irradiation begins with the deepest layer 926i, progresses one layer at a time to successively shallower layers, and ends with the shallowest layer 926a. Prior to application to the body 922, the energy of the particle beam 914 is controlled to a level that allows the particle beam to stop at a desired layer (e.g., layer 926d) without substantially further penetrating into the body or target volume, e.g., layers 926e-926i or deeper into the body. In some examples, the desired energy of the particle beam 914 decreases as the treatment layer progresses shallower relative to the particle acceleration. In some examples, the beam energy difference for treating adjacent layers of the target volume 924 is about 3 MeV to about 100 MeV, e.g., about 10 MeV to about 80 MeV, although other differences are possible depending on, e.g., the thickness of the layers and the nature of the beam.

[0191] The energy variation for treating different layers of the target volume 924 can be performed at the accelerator 912 (e.g., the accelerator can vary the energy), such that in some implementations no additional energy variation is needed after the particle beam is extracted from the accelerator 912. Thus, the optional energy degrader 920 in the treatment system 10 can be eliminated from the system. In some implementations, the accelerator 912 can output a particle beam having an energy that varies between about 100 MeV and about 300 MeV (e.g., between about 115 MeV and about 250 MeV). The variation can be continuous or non-continuous, e.g., one step at a time. In some implementations, the continuous or non-continuous variation can occur at a relatively high rate, e.g., up to about 50 MeV / second or up to about 20 MeV / second. The non-continuous variation can occur one step at a time, with a step size of about 10 MeV to about 90 MeV.

[0192] When irradiation is complete in a layer, the accelerator 912 can vary the energy of the particle beam to irradiate the next layer, e.g., within a few seconds or within less than a second. In some implementations, treatment of the target volume 924 can continue without substantial interruption or even without any interruption. In some cases, the step size of the non-continuous energy variation is selected to correspond to the energy difference required to irradiate two adjacent layers of the target volume 924. For example, the step size can be the same as the energy difference or a fraction of the energy difference.

[0193] In some implementations, the accelerator 912 and the degrader 920 collectively vary the energy of the beam 914. For example, the accelerator 912 provides coarse tuning and the degrader 920 provides fine tuning, or vice versa. In this example, the accelerator 912 can output a particle beam that varies in energy with a step size of about 10-80 MeV, and the degrader 920 adjusts (e.g., reduces) the energy of the beam with a step size of about 2-10 MeV.

[0194] The reduced use (or absence) of energy reducers (such as range modulators) can help maintain the properties and quality of the output beam from the accelerator, such as beam strength. Particle beam control can be performed at the accelerator. For example, the side effects of neutrons produced when the particle beam passes through reducer 920 can be reduced or eliminated.

[0195] The energy of the particle beam 914 can be adjusted to treat another target volume 930 in another body or body part 922' after treatment in target volume 924 has been completed. Target volumes 924 and 930 can be in the same body (or patient) or in different patients. The depth D of target volume 930 from the surface of body 922' may differ from the depth of target volume 924. Although some energy adjustments can be made by the downgrader 920, the downgrader 912 can only reduce the beam energy, not increase it.

[0196] In some cases, the beam energy required to treat target volume 930 is greater than that required to treat target volume 924. In such cases, accelerator 912 can increase the output beam energy after treating target volume 924 and before treating target volume 930. In other cases, the beam energy required to treat target volume 930 is less than that required to treat target volume 924. Although degrader 920 can reduce the energy, accelerator 912 can be adjusted to output lower beam energy, thereby reducing or eliminating the use of degrader 920. Target volumes 924 and 930 can be divided into layers, which can be different or the same. Target volume 930 can be treated layer by layer to treat target volume 924.

[0197] Treatment of different target volumes 924 and 930 for the same patient can be substantially continuous, for example, with a pause time between the two volumes not exceeding approximately 30 minutes or less, such as 25 minutes or less, 20 minutes or less, 15 minutes or less, 10 minutes or less, 5 minutes or less, or 1 minute or less. As explained herein, the accelerator 912 can be mounted on a movable gantry, and movement of the gantry can move the accelerator to target different target volumes. In some cases, the energy adjustment of the output beam 914 can be completed after treatment of target volume 924 is finished and during system adjustments (e.g., gantry movement) before treatment of target volume 930 begins. After the accelerator and target volume 930 are aligned, treatment can begin with the adjusted required beam energy. Beam energy adjustments for different patients can also be performed relatively efficiently. In some examples, all adjustments, including increasing / decreasing beam energy and / or moving the gantry, are completed within approximately 30 minutes, for example, within approximately 25 minutes, within approximately 20 minutes, within approximately 15 minutes, within approximately 10 minutes, or within 5 minutes.

[0198] In the same layer of the target volume, the irradiation dose can be applied by using the scanning unit 916 to move a two-dimensional surface of the beam across the layer, sometimes referred to as a scanning beam. Alternatively, the layers can be irradiated by passing the extracted beam through one or more scatterers of the scattering unit 16, sometimes referred to as a scattering beam.

[0199] The beam properties, such as energy and intensity, can be selected prior to treatment, or can be adjusted during treatment by controlling the accelerator 912 and / or other devices (e.g., scanning unit(s) / scatterer 916, degrader 920, and / or other devices not shown in the figure). In an example implementation, the system 910 includes a controller 932, e.g., a computer, in communication with one or more devices in the system. The control can be based on the results of monitoring performed by one or more monitors 918, e.g., monitoring the beam intensity, dose, beam position in the target volume, etc. Although the monitors 918 are shown between the device 916 and the degrader 920, one or more monitors can be placed at other appropriate locations along the beam irradiation path. The controller 932 can also store treatment plans for one or more target volumes (for the same patient and / or different patients). The treatment plans can be determined prior to the start of treatment, and can include parameters such as the shape of the target volume, the number of irradiation layers, the irradiation dose per layer, the number of times each layer is irradiated, etc. Adjustments of the beam characteristics can be made within the system 910 based on the treatment plans. Additional adjustments can be made during treatment, e.g., when deviations from the treatment plan are detected.

[0200] In some embodiments, the accelerator 912 is configured to change the energy of the output particle beam by changing the magnetic field in which the particle beam is accelerated. In an example embodiment, one or more sets of coils receive variable currents to produce a variable magnetic field in the cavity. In some examples, one set of coils receives a fixed current, while one or more other sets of coils receive variable currents, such that the total current received by the set of coils varies. In some embodiments, all sets of coils are superconducting. In other embodiments, some sets of coils (e.g., the set for the fixed current) are superconducting, while other sets of coils (e.g., one or more sets for the variable current) are non-superconducting. In some examples, all sets of coils are non-superconducting.

[0201] Generally, the strength of the magnetic field can scale with the strength of the current. Adjusting the total current to the coils within a predetermined range can produce a magnetic field that varies within a corresponding predetermined range. In some examples, continuous adjustment of the current can result in continuous variation of the magnetic field and continuous variation of the output beam energy. Alternatively, when the current applied to the coils is adjusted in a non-continuous, step-wise manner, the magnetic field and the output beam energy also vary in a non-continuous (step-wise) manner accordingly. Scaling the magnetic field to the current can allow relatively precise variation of the beam energy, although sometimes minor adjustments other than the input current can be made.

[0202] In some embodiments, to output particle beams having variable energies, the accelerator 912 is configured to apply an RF voltage that sweeps through different frequency ranges, each range corresponding to a different output beam energy. For example, if the accelerator 912 is configured to produce three different output beam energies, the RF voltage can sweep through three different frequency ranges. In another example, the RF voltage sweeps over a continuously varying frequency range corresponding to a continuous beam energy variation. The different frequency ranges can have different lower and / or upper frequency boundaries.

[0203] The extraction channel can be configured to accommodate the range of different energies produced by the energy-variable particle accelerator. For example, the extraction channel can be large enough to support the highest and lowest energies produced by the particle accelerator. That is, the extraction channel can be sized or otherwise configured to receive and transport particles within that energy range. Particle beams having different energies can be extracted from the accelerator 912 without changing the characteristics of the regenerators used to extract particle beams having a single energy. In other embodiments, to accommodate the variable particle energies, the regenerators can be moved to perturb (e.g., change) the different particle orbits in the manner described above, and / or magnetic shims can be added or removed to change the magnetic field inhomogeneity provided by the regenerators. More specifically, different particle energies will typically be on different particle orbits within the cavity. By moving the regenerators, the particle orbits can be intercepted at a specified energy, thereby providing the correct perturbation of that orbit so that particles of the specified energy reach the extraction channel. In some embodiments, the movement of the regenerators (and / or the addition / removal of magnetic shims) is performed in real-time to match real-time changes in the particle beam energy output by the accelerator. In other embodiments, the particle energy is adjusted on a per-treatment basis, and the movement of the regenerators (and / or the addition / removal of magnetic shims) is performed prior to the treatment. In either case, the movement of the regenerators (and / or the addition / removal of magnetic shims) can be computer-controlled. For example, a computer can control one or more motors that effect the movement of the regenerators and / or magnetic shims.

[0204] In some embodiments, the regenerators are implemented using one or more magnetic shims, which can be controlled to move to the appropriate location(s).

[0205] As an example, Table 1 shows three example energy levels at which an exemplary accelerator 912 can output particle beams. Also listed are the corresponding parameters used to produce the three energy levels. In this regard, the magnet current refers to the total current applied to one or more coil sets in the accelerator 912; the maximum and minimum frequencies define the range over which the RF voltage sweeps; and "r" is the radial distance of the location from the center of the cavity in which the ions are accelerated.

[0206]

[0207] Table 1. Examples of beam energy and corresponding parameters

[0208] The following describes details of an example particle accelerator that can be included to produce charged particles with variable energies. The accelerator may be a synchrotron, and the particles may be protons. The particles may be output as a pulsed beam. The energy of the beam output from the particle accelerator may vary during treatment of a target volume of a patient or between treatments of different target volumes of the same patient or different patients. In some embodiments, when no beam (or particles) is output from the accelerator, the accelerator settings are changed to alter the beam energy. The energy variation may be continuous or discontinuous within the desired range.

[0209] refer to Figure 1 The example shown is a particle accelerator (e.g., a synchrotron accelerator), which can be a variable-energy particle accelerator as described above, such as accelerator 912, and can be configured to output a particle beam with variable energy. The range of variable energy can have an upper limit of approximately 200 MeV to approximately 300 MeV or higher, such as 200 MeV, approximately 205 MeV, approximately 210 MeV, approximately 215 MeV, approximately 220 MeV, approximately 225 MeV, approximately 230 MeV, approximately 235 MeV, approximately 240 MeV, approximately 245 MeV, approximately 250 MeV, approximately 255 MeV, approximately 260 MeV, approximately 265 MeV, approximately 270 MeV, approximately 275 MeV, approximately 280 MeV, approximately 285 MeV, approximately 290 MeV, approximately 295 MeV, or approximately 300 MeV or higher. This range may also have a lower boundary of about 100 MeV or less to about 200 MeV, such as about 100 MeV or less, about 105 MeV, about 110 MeV, about 115 MeV, about 120 MeV, about 125 MeV, about 130 MeV, about 135 MeV, about 140 MeV, about 145 MeV, about 150 MeV, about 155 MeV, about 160 MeV, about 165 MeV, about 170 MeV, about 175 MeV, about 180 MeV, about 185 MeV, about 190 MeV, about 195 MeV, and about 200 MeV.

[0210] In some examples, the changes are discontinuous, and the change step size can be approximately 10 MeV or smaller, approximately 15 MeV, approximately 20 MeV, approximately 25 MeV, approximately 30 MeV, approximately 35 MeV, approximately 40 MeV, approximately 45 MeV, approximately 50 MeV, approximately 55 MeV, approximately 60 MeV, approximately 65 MeV, approximately 70 MeV, approximately 75 MeV, or approximately 80 MeV or larger. Changing the energy by one step size can take no more than 30 minutes, for example, approximately 25 minutes or less, approximately 20 minutes or less, approximately 15 minutes or less, approximately 10 minutes or less, approximately 5 minutes or less, approximately 1 minute or less, or approximately 30 seconds or less. In other examples, the changes are continuous and the accelerator can modulate the particle beam energy at relatively high rates, such as up to about 50 MeV per second, up to about 45 MeV per second, up to about 40 MeV per second, up to about 35 MeV per second, up to about 30 MeV per second, up to about 25 MeV per second, up to about 20 MeV per second, up to about 15 MeV per second, or up to about 10 MeV per second. The accelerator can be configured to modulate the particle energy continuously and discontinuously. For example, a combination of continuous and discontinuous changes can be used to treat a single target volume or to treat different target volumes. Flexible treatment planning and flexible treatment can be achieved.

[0211] Particle accelerators that output particle beams with variable energy can provide precision in irradiation treatment and reduce the number of additional devices (besides the accelerator) required for therapy. For example, for full or partial therapy, the use of degraders to alter the energy of the output particle beam can be reduced or eliminated. The properties of the particle beam (such as intensity, focus, etc.) can be controlled at the particle accelerator, and the beam can reach the target volume without substantial interference from additional devices. The relatively high rate of change of beam energy can reduce treatment time and allow for efficient use of the therapy system.

[0212] In some implementations, accelerators (such as Figure 1 A synchrotron accelerator accelerates particles or particle beams to variable energy levels by altering the magnetic field within the accelerator. This can be achieved by changing the current applied to the coils to generate the magnetic field. As explained above, an exemplary synchrotron accelerator (e.g., Figure 1 It includes a magnet system, which contains a particle source, a radio frequency drive system, and a beam extraction system. Figure 33An example of a magnet system 1010 that can be used in a variable energy accelerator is shown. In this example embodiment, the magnetic field established by the magnet system 1012 can be varied by about 5% to about 35% of the maximum value of the magnetic field that the two sets of coils 40a and 40b and 42a and 42b are capable of generating. The magnetic field established by the magnet system has a shape that is suitable for maintaining the focus of the proton beam using a combination of two sets of coils and a pair of shaped ferromagnetic (e.g., low carbon steel) structures, examples of which are provided above.

[0213] Each set of coils can be a split pair of separate toroidal coils to receive current. In some cases, both sets of coils are superconducting. In other cases, only one set of coils is superconducting, while the other set is non-superconducting or normally conducting (also discussed further below). Both sets of coils can also be non-superconducting. Superconducting materials suitable for the coils include niobium 3 tin (Nb3Sn) and / or niobium titanium. Other conventional conducting materials can include copper. Examples of coil set configurations are described further below.

[0214] The two sets of coils can be electrically connected in series or in parallel. In some embodiments, the total current received by the two sets of coils can include about 2 million ampere turns to about 10 million ampere turns, such as about 2.5 million to about 7.5 million ampere turns, or about 3.75 million ampere turns to about 5 million ampere turns. In some examples, one set of coils is configured to receive a fixed (or constant) portion of the total variable current, while the other set of coils is configured to receive a variable portion of the total current. The total current of the two coil sets varies as the current in one coil set varies. In other cases, the current applied to both sets of coils can vary. The variable total current in the two sets of coils can produce a magnetic field having a variable strength, which in turn changes the acceleration path of the particles and produces particles having a variable energy.

[0215] Generally, the strength of the magnetic field produced by the coil(s) is scalable to the strength of the total current applied to the coils. Based on the scalability, in some embodiments, a linear change in the strength of the magnetic field can be achieved by linearly changing the total current of the coil sets. The total current can be adjusted at a relatively high rate, which results in a relatively high rate of adjustment of the magnetic field and the beam energy.

[0216] In the example reflected in Table 1 above, the ratio between the values of the current and the magnetic field at the geometric center of the coil ring is: 1990:8.7 (approximately 228.7:1); 1920:8.4 (approximately 228.6:1); 1760:7.9 (approximately 222.8:1). Accordingly, adjusting the strength of the total current applied to the superconducting coil(s) can proportionally (based on this ratio) adjust the strength of the magnetic field.

[0217] In some embodiments, the total current applied to the superconducting coil(s) can be adjusted at a rate of about 1 kHz to about 10 kHz, such as about 1 kHz to about 5 kHz, or about 1 kHz to about 2 kHz. In some examples, the total current applied to the superconducting coil(s) can be adjusted at a rate of about 1 kHz to about 10 kHz, such as about 1 kHz to about 5 kHz, or about 1 kHz to about 2 kHz. Figure 31The plot also illustrates the scalability of the magnetic field with respect to the total current, where Bz is the magnetic field along the Z direction; R is the radial distance measured from the geometric center of the coil loops along a direction perpendicular to the Z direction. The magnetic field has its highest value at the geometric center and decreases with increasing distance R. Curves 1035 and 1037 represent the magnetic fields produced by the same coil group receiving different total currents: 1760 amperes and 1990 amperes, respectively. The corresponding energies of the extracted particles are 211 MeV and 250 MeV, respectively. The two curves 1035 and 1037 have substantially the same shape, and different portions of curves 1035 and 1037 are substantially parallel. Therefore, curve 1035 or curve 1037 can be linearly shifted to substantially match the other curve, indicating that the magnetic field is scalable to the total current applied to the coil group.

[0218] In some implementations, the scalability of the magnetic field to the total current may not be perfect. For example, the ratio between the magnetic field and the current calculated based on the examples shown in Table 1 is not constant. Furthermore, as... Figure 31 As shown, a linear offset of one curve may not perfectly match another curve. In some implementations, the total current is applied to the coil assembly under the assumption of perfect scalability. The target magnetic field (under the assumption of perfect scalability) can be generated by additionally altering the characteristics (e.g., geometry) of the coils to counteract the imperfections of scalability. As an example, a ferromagnetic (e.g., iron) rod (magnetic pad) can be inserted or removed from one or two magnetic structures (e.g., yoke, pole piece, etc.). The characteristics of the coils can be changed at a relatively high rate, such that the rate of magnetic field adjustment is substantially unaffected compared to the case of perfect scalability where only the current needs to be adjusted. In the example of the iron rod, the rod can be added or removed on a timescale of seconds or minutes, such as within 5 minutes, within 1 minute, less than 30 seconds, or less than 1 second.

[0219] In some implementations, the accelerator settings, such as the current applied to the coil group, can be selected based on the substantial scalability of the magnetic field to the total current in the coil group.

[0220] In general, to generate a total current varying within the desired range, any suitable combination of currents applied to the two coil groups can be used. In the example, coil groups 42a and 42b can be configured to receive a fixed current corresponding to the lower boundary of the desired magnetic field range. In the example shown in Table 1, the fixed current is 1760 amperes. Alternatively, coil groups 40a and 40b can be configured to receive a variable current having an upper boundary corresponding to the difference between the upper and lower boundaries of the desired magnetic field range. In the example shown in Table 1, coil groups 40a and 40b are configured to receive a current varying between 0 amperes and 230 amperes.

[0221] In another example, the coil sets 42a, 42b can be configured to receive a fixed current corresponding to an upper boundary of the desired magnetic field range. In the example shown in Table 1, the fixed current is 1990 amperes. Additionally, the coil sets 40a, 40b can be configured to receive a variable current having an upper boundary corresponding to a difference between the lower and upper boundaries of the desired magnetic field range. In the example shown in Table 1, the coil sets 40a, 40b are configured to receive a current that varies between -230 amperes and 0 amperes.

[0222] The total variable magnetic field generated by the variable total current for accelerating the particles can have a maximum magnitude greater than 4 Tesla, for example, greater than 5 Tesla, greater than 6 Tesla, greater than 7 Tesla, greater than 8 Tesla, greater than 9 Tesla, or greater than 10 Tesla, and up to about 20 Tesla or more, for example, up to about 18 Tesla, up to about 15 Tesla, or up to about 12 Tesla. In some embodiments, the change in total current in the coil sets can cause the magnetic field to change by about 0.2 Tesla to about 4.2 Tesla or more, for example, about 0.2 Tesla to about 1.4 Tesla, or about 0.6 Tesla to about 4.2 Tesla. In some cases, the amount of change in the magnetic field can be proportional to the maximum magnitude.

[0223] Figure 32 An example RF structure is shown for sweeping a voltage over the D-shaped plate 500 over the RF frequency range for each energy level of the particle beam and for changing the frequency range as the particle beam energy varies. The semi-circular surfaces 503, 505 of the D-shaped plate 500 are connected to the inner conductor 1300 and are housed in the outer conductor 1302. A high voltage is applied to the D-shaped plate 500 from a power supply (not shown, e.g., an oscillating voltage input) through a power supply coupling 1304 that couples the power supply to the inner conductor. In some embodiments, the coupling 1304 is positioned on the inner conductor 1300 to provide power transfer from the power supply to the D-shaped plate 500. Additionally, the D-shaped plate 500 is coupled to variable reactance elements 1306, 1308 to perform RF frequency scanning for each particle energy level and to change the RF frequency range for different particle energy levels.

[0224] The variable reactance element 1306 may be a rotating capacitor having a plurality of blades 1310 rotatable by a motor (not shown). By engaging or disengaging the blades 1310 during each cycle of the RF sweep, the capacitance of the RF structure changes, which in turn alters the resonant frequency of the RF structure. In some embodiments, the blades 1310 engage with each other during each quarter cycle of the motor. The capacitance of the RF structure increases and the resonant frequency decreases. When the blades 1310 disengage, the process is reversed. Therefore, the power required to generate the high voltage applied to the D-shaped plate 103 and accelerate the beam can be significantly reduced. In some embodiments, the shape of the blades 1310 is machined to create the desired correlation between the resonant frequency and time.

[0225] By sensing the phase of the RF voltage in the resonator, the AC voltage on the D-shaped plate is kept close to the resonant frequency of the RF cavity, thus synchronizing the RF frequency generation with the blade rotation. (The D-shaped plate is dummy grounded, and no...) Figure 32 (as shown in the image).

[0226] The variable reactance element 1308 can be a capacitor formed by a plate 1312 and a surface 1316 of an inner conductor 1300. The plate 1312 can move toward or away from the surface 1316 along a direction 1314. As the distance D between the plate 1312 and the surface 1316 changes, the capacitance of the capacitor changes. For each frequency range to be swept for a particle energy, the distance D is at a set value, and in order to change the frequency range, the plate 1312 moves accordingly to the change in the energy of the output beam.

[0227] In some embodiments, the inner conductor 1300 and outer conductor 1302 are formed of a metallic material, such as copper, aluminum, or silver. The blade 1310 and plate 1312 may also be formed of the same or different metallic material as conductors 1300 and 1302. The coupling device 1304 may be an electrical conductor. Variable reactance elements 1306 and 1308 may have other forms and may be coupled to the D-shaped plate in other ways for RF frequency sweeping and frequency range changing. In some embodiments, a single variable reactance element may be configured to perform the functions of both variable reactance elements 1306 and 1308. In other embodiments, more than two variable reactance elements may be used.

[0228] Return to reference Figure 3 And also refer to Figure 34 In particle accelerator 3401 (which may have Figure 1 , Figure 2 The output of the lead-out channel (as shown in the configuration) is a scanner composed of scanning components 3402, such as a scanning magnet. (As per...) Figure 3As described, in example operations, the scanning magnet is controllable in one or more (e.g., at least two) dimensions (e.g., Cartesian XY dimensions) to direct the particle beam across a portion (e.g., a cross-section) of the irradiation target. The ion chamber detects the dose of the beam and feeds this information back to the control system to adjust the beam movement. The energy degrader is controllable to move one or more elements (e.g., plates) into and out of the path of the particle beam to change the energy of the particle beam, and thus the depth (Z direction) of the particle beam that will penetrate the irradiation target. For example, the energy degrader can include one or more computer-controlled motors that drive one or more plates into the beam field and retract the one or more plates from the beam field in sequence. In some embodiments, the beam field corresponds to the maximum lateral extent that the particle beam can move in a given direction, e.g., in the Cartesian XY plane over the irradiation target, e.g., as shown in Figure 19 .

[0229] As described herein, the scanning of the particle beam does not wait for the plates to move into position, but rather the scanning of the particle beam can occur during the movement of the plates. Although scanning can occur during the movement of the plates, scanning can also occur when the plates are stationary or absent. For example, in some cases, to reach the deepest layers of the target, it is not necessary to move the plates into the path of the particle beam. Also, in some cases, all of the plates can be positioned and stationary when the scanning occurs. In some embodiments, the energy degrader can have configurations and operations as described with respect to Figures 36 to 49 , which are described below.

[0230] Referring to Figure 34 , an energy degrader 3403, which can have configurations and operations as described with respect to Figures 36 to 49 , is positioned between the particle accelerator 3401 and the irradiation target 3405 (e.g., a tumor of a patient). For example, the energy degrader 3403 can be positioned on the nozzle 610 of the inner gantry 601 Figure 29 , and can be controlled by a computer system that also controls the operation of other components of the particle therapy system. The operation of the energy degrader 3403 can be coordinated with and controlled by the operation of the scanning components, the particle accelerator, and the operation of the inner and outer gantries described herein to implement the particle therapy processes described herein and variations thereof.

[0231] In some embodiments, the passage of the beam through the energy degrader can cause further divergence of the beam. Accordingly, an aperture 3404 can be positioned between the energy degrader and the irradiation target. As described herein, the aperture can be controllable to further shape the beam.

[0232] In an example, each plate of the energy degrader positioned in the particle beam path absorbs an amount of energy in the particle beam. Correspondingly, the more plates placed in the particle beam path, the less energy the beam has and the shallower the beam will penetrate into the irradiation target. Conversely, the fewer plates placed in front of the particle beam, the more energy the beam has (because less energy is absorbed by the plate(s)) and the deeper the beam will penetrate into the irradiation target. Thus, for a given plate of the energy degrader, the energy of the particle beam incident on the plate exceeds the energy of the particle beam after passing through the plate. In some embodiments, the plates can be made of one or more of the following example materials: polycarbonate, carbon, beryllium, or other materials with low atomic number. However, other materials can be used instead of or in addition to these example materials. As described herein, a treatment plan can specify the configuration of the energy degrader at any particular time during treatment, and feedback from ionization in the ionization chamber can be used for beam positioning and positioning corrections.

[0233] The energy degrader can be a high-speed energy switching range shifter. In one example, this type of energy degrader contains one or more elements (e.g., one or more plates) that move during scanning during movement of the particle beam. For example, the plate(s) can move from a start position toward an end position, and the particle beam moves across the surface of the plate(s) in one or more dimensions as the plate(s) move. For example, the particle beam can move across the surface of the plate(s) in one dimension, in two dimensions, or in three dimensions, and ultimately across the irradiation target. For example, Figure 49 A top perspective view of an example plate 4901 is shown. A spot 4902 of a particle beam is scanned in an example two-dimensional path labeled 4903a, 4903b, 4903c, 4903d, and 4903e. Example future positions of the spot 4902 during scanning are labeled 4902a, 4902b, 4902c, 4902d, and 4902e, although it should be noted that the spot will appear at all positions along the two-dimensional path.

[0234] The speed of movement of the beam in the direction of movement can be the same, slower, or faster than the speed of movement of the plate(s) in the direction of movement (as long as the beam remains on the surface of the plate). In some embodiments, if the beam moves faster than the plate, the beam can stop to wait for the plate. As described herein, the simultaneous movement of the plate and the particle beam can reduce treatment time relative to some known energy degraders.

[0235] In some embodiments, each plate has a uniform thickness, as Figure 36As shown. That is, in such embodiments, the thickness variation on each plate is small or non-existent. In some embodiments, the plates of the energy degrader may each have the same thickness, defined as a "step." In this context, the step refers to the distance between two layers of the target to be treated. That is, the thickness may correspond to, for example, the beam energy required to hit a single layer of the irradiated target. In some embodiments, plates are not used to reach the deepest layer of the irradiated target. For example, the energy degrader may be configured such that no plate is in the path of the particle beam, and the particle beam simply passes through without energy variation to reach the irradiated target. Plates are then added to reach other shallower layers. That is, to reach shallower layers of the irradiated target, plates are moved into the beam field / treatment area and into the path of the particle beam.

[0236] As an example, refer to Figure 35 An exemplary irradiation target 3500 can be divided into ten layers 3499, 3501, 3502, 3503, 3504, 3505, 3506, 3507, 3508, and 3509 (also referred to as steps), each layer being treated by scanning a particle beam across these layers. Layer 3499 is located at the deep end 3510 of the target and requires the most energy to hit, while layer 3509 is located at the shallow end 3511 of the target and requires the least energy to hit. Accordingly, in this exemplary embodiment, no plate moves into the path of the particle beam to hit layer 3499. That is, the particle beam passes through the energy degrader without energy change. Subsequently, in exemplary operation, using plates having thicknesses corresponding to a single step (e.g., the energy level of a layer), a single plate can be moved into the beam path to change the energy of the beam, such that the beam hits layer 3501; two plates can be moved into the beam path to change the energy of the beam, such that the beam hits layer 3502; three plates can be moved into the beam path to change the energy of the beam, such that the beam hits layer 3503, and so on, until all layers are treated. As described herein, as the plates (multiple plates) move across the beam field, the particle beam moves across the plates (multiple plates) (and thus ultimately across the corresponding layers), thereby treating the irradiated target in time not previously used for treatment.

[0237] In some implementations, the different plates within the energy degrader may have different thicknesses. For example, in some implementations, the energy degrader may contain a first plate having a first thickness and multiple additional plates, each additional plate having a second thickness different from the first thickness, such as... Figure 37 As shown. In the example, the first plate may have a thickness (e.g., a single step) corresponding to the beam energy required to hit a single layer of the irradiated target. Additional plates may each be thicker than the first plate. For example, each additional plate may have a thickness of two steps, or twice the thickness of the first plate, to allow the combination of the first plate and the other plates to generate the beam energy required to hit each layer within the irradiated target. Reference Figure 35In example embodiments, the first plate and additional plates can be used to treat the target 3500 as follows. To treat layer 3499, all plates can be removed from the beam path. To treat layer 3501, the first plate can be moved into the beam path. To treat layer 3502, the first plate can be retracted from the beam path and an additional plate (having twice the thickness of the first plate) can be moved into the beam path. To treat layer 3503, both the first plate (having a single step thickness) and the additional plate (having a two step thickness) can be moved into the beam path. To treat layer 3504, the first plate can be removed from the beam path and two additional plates (each having a two step thickness) can be placed in the beam path. This process involves introducing zero, one or more second plates and the first plate for odd layers, does not involve the deepest layer 3499 (e.g., in this example, layers 3501, 3503, 3505, 3507, and 3509), and retracts the first plate for even layers (e.g., in this example, layers 3502, 3504, 3506, and 3508) until all layers of the target have been treated. As described herein, as the plate(s) move across the beam field, the particle beam moves across the plate(s) (and ultimately across the corresponding layer of the irradiation target) to treat the irradiation target in the time that has so far been unused for treatment.

[0238] In some embodiments, individual plates can have different thicknesses than described herein. For example, plates can have more than two different thicknesses and can be appropriately ordered to hit all layers of a radiation target. For example, an energy degrader can include a first plate having a single step length, and additional plates that are thicker than the first plate. For example, some additional plates can be two step length thick, while other plates are three step length thick, four step length thick, eight step length thick, etc. For example, with reference to FIG. 3, the first plate 301 can be a single step length thick, the additional plate 302 can be two step length thick, the additional plate 303 can be three step length thick, the additional plate 304 can be four step length thick, and the additional plate 305 can be eight step length thick. Figure 35The target 3500 can be treated using the first plate and additional plates as follows. To treat layer 3499, all plates can be removed from the beam path. To treat layer 3501, the first plate can be moved into the beam path. To treat layer 3502, the first plate can be removed from the beam path and a second additional plate (having twice the thickness of the first plate) can be moved into the beam path. To treat layer 3503, the first plate and the second plate can be removed from the beam path and a third additional plate (having three times the thickness of the first plate) can be moved into the beam path. To treat layer 3504, the third additional plate (having three-step thickness) can be left in the beam path and the first plate (having one-step thickness) can be moved into the beam path. To treat layer 3505, the third additional plate can be left in the beam path, the first plate can be removed from the beam path, and the second additional plate (having two-step thickness) can be moved into the beam path. This process, which involves moving different plates into the beam path at different times based on the desired energy level, can be performed until all layers of the target have been treated. As described herein, as the plate(s) move across the beam field, the particle beam moves across the plate(s), thereby processing the irradiation target at times that have not been used for treatment thus far.

[0239] In some embodiments, the layers can be processed, but need not be, in depth order. In this regard, reference is made to Figure 35 The plates of the energy degrader can be ordered so that layer 3499 is treated first, then layer 3501, then layer 3502, then layer 3503, and so on until all layers have been treated in order, or so that layer 3509 is treated first, then layer 3508, then layer 3507, and so on until all layers have been treated in order. However, in some embodiments, the plates of the energy degrader can be ordered so that the layers are not treated in depth order, e.g., layer 3503 is treated first, then layer 3508, then layer 3501, then layer 3501, then other layers, until all layers have been treated. The order in which the layers are treated can be determined by a treatment plan, which can be based at least in part on the configuration of the energy degrader.

[0240] In some embodiments, using fewer plates can reduce the number of moving parts in the energy degrader, making the energy degrader less prone to mechanical failure. Fewer plates can also reduce the size of the energy degrader, allowing the energy degrader to be positioned relatively close to the patient being treated. Moving plates into or out of the beam path can be noisy. Using plates having different thicknesses can reduce the number of plates that need to be moved into the beam path, which in some cases can reduce the noise during treatment.

[0241] Figure 36 An example energy degrader 3600 having multiple plates is shown, each plate corresponding to a single step. Figure 37An example energy degrader 3700 is shown that also has multiple plates, with one plate 3701 corresponding to a single step, and multiple other plates 3702 each corresponding to two steps (in other words, in this example, plate 3701 is half the thickness of each plate 3702). Energy degrader 3700 can need to move fewer plates to hit all the layers of a target than energy degrader 3600, and thus can be lower noise, smaller, and less susceptible to mechanical failure in some cases. In some embodiments, energy degrader 3700 can include multiple single-step plates (like plate 3701) and multiple thicker plates (like plates 3702). In some embodiments, energy degrader 3700 can include a single thicker plate (like plate 3702) and multiple single-step plates (like plate 3701).

[0242] In the example energy degraders described herein, individual plates can be moved into and out of the path of the particle beam, and can continue their movement as the particle beam moves during a scan. More specifically, in some known energy degraders, the plates are positioned before the particle beam is scanned. After positioning, the scan is performed, and then stopped as the plates are repositioned. Treatment time can be extended in systems such as these. By moving the particle beam during the movement of its plates, as described herein, example energy degraders can reduce treatment time relative to that achieved using known systems. This is because both the particle beam and the plates are moving simultaneously. Thus, time that was previously used to move the plates before the patient was treated can be used for actual treatment.

[0243] In some embodiments, the same computer system that controls the energy degrader also controls the movement of the particle beam during a scan. In some embodiments, different computer systems control the operation of the energy degrader and the movement of the particle beam. In either case, the operation of the energy degrader and / or scanner can be coordinated so that the particle beam passes through the appropriate number of plate(s) to treat the desired layers, while those plate(s) are moving across at least a portion of the beam field. In some embodiments, the operation of the energy degrader also includes causing the particle beam to pass through plates whose movement has stopped, as also described herein.

[0244] Reference is made to Figure 38 In example operation, plates 3801, 3802 of the energy degrader are controllable to move in the same direction (in this example, the direction of arrow 3803), and simultaneously during the movement of particle beam 3804 during a scan. In this example, the movement of particle beam 3804 during the movement of the plates is represented by arrow 3806. In this example, the particle beam is represented by a solid line when it is moving, and a dashed line when it is not moving. Figure 38 In the example of FIG. 38, the movement of particle beam 3804 during the movement of the plates is represented by arrow 3806. In this example, the particle beam is represented by a solid line when it is moving, and a dashed line when it is not moving. Figure 38 In the example of FIG. 38, and in other figures presented subsequently, the particle beam at a future position after movement is represented by a dashed line. In this example, the particle beam is represented by a solid line when it is moving, and a dashed line when it is not moving. Figure 38In the example and other figures presented subsequently, the plate of the energy degrader at the future position after the movement is represented in dashed lines. Only a portion of the plate at the future position can be represented (as in the case of Figure 38 the current and future positions of the plate can overlap, and the current plate position is represented in solid lines.

[0245] In example operations, the particle beam 3804 passes through one or more plates (e.g., at least partially) of the energy degrader while a corresponding plate is in motion. For example, Figure 38 A first plate 3801 and a second plate 3802 are shown, both of which are part of an example energy degrader. The first plate 3801 and the second plate 3802 are controllable to move in the direction of the arrow 3803. In this example, the particle beam is orthogonal to the plates, but this is not necessarily the case in some embodiments. For example, the particle beam can be non-orthogonal to the plates, as in the case of intensity-modulated proton therapy, as described with respect to Figure 18 The particle beam is represented by a spot 3807 on the plate (here, the plate 3802) on which the particle beam is incident.

[0246] In example operations, the plate 3802 begins to move in the direction of the arrow 3803 toward / into the beam field 3809. The scan can begin at any suitable time after the plate 3802 is in the beam field. When the scan begins will be determined by the treatment plan, which identifies the location of the radiation target relative to the plates of the energy degrader. As described herein, the scan can begin in the beam field before any plate is in the beam field. For example, in some embodiments, to scan the deepest layer in the target, no change in beam energy is required, and thus, no plate is in the path of the beam. However, at any suitable time before or after the scan begins, the plate can begin to move toward and into the beam field, including as the deepest layer is being scanned, the plate can move into the beam field but follow the beam path.

[0247] In some embodiments, the movement of the particle beam across the plate 3802 is limited to outside a predetermined distance from the edge 3810 of the plate 3802. For example, the energy degrader and / or the scanning system can be controlled so that the particle beam does not pass near the edge 3810. This is because, as Figure 39As shown, the spot incident on the plate 3802 has a Gaussian distribution 3900 of particles. Accordingly, applying the spot near (e.g., within a distance) of the edge 3810 of the plate 3802 can result in some particles inadvertently passing unimpeded to the patient. Accordingly, the operation of the scanning system and / or the energy degrader can be controlled such that the spot is applied away from at least one edge, and in some cases all edges, of the plate. In some embodiments, the minimum distance between the spot and the plate edge is in the range of 2s to 2.5s, where s is one standard deviation of a Gaussian curve representing the distribution of particles in the spot. However, the embodiments described herein are not limited to distances in the range of 2s to 2.5s.

[0248] Referring back to Figure 38 , movement of the particle beam across the plate 3802 produces an energy-degraded particle beam 3799 that is applied to the irradiation target 3814. That is, the particle beam passes through the plate 3802, thereby changing (e.g., degrading) the energy of the particle beam to enable the particle beam to hit the corresponding energy layer (step) of the irradiation target. In this example, at some point in time after the movement of the plate 3802 begins, and while the plate 3802 is moving and the movement of the particle beam continues, the plate 3801 also begins to move in the direction of arrow 3803. During its movement, the plate 3801 partially overlaps and follows the plate 3802, and the two plates continue to move simultaneously for at least a period of time. In some embodiments, the edge 3810 of the plate 3802 can move at least 2s to 2.5s distance relative to the edge 3812 of the plate 3801 before the plate 3801 begins to move; however, in other implementations, different criteria can be used. In some embodiments, there is no following plate. For example, in Figure 38 , the plate 3801 can not begin to move until the plate 3802 has reached its end position or until the plate 3802 has moved to its end position and then retracted to its start position (e.g., the plate 3801 can not follow the plate 3802).

[0249] Figure 38A and Figure 38B depicts the plate without the dashed lines at different points during scanning of the irradiation target 3814. Figure 38

[0250] At some time, the movement of the particle beam across the plate 3802 will be complete - e.g., the entire layer corresponding to the steps of the plate 3802 can be scanned. Thereafter, the next layer of the irradiation target can be begun to be scanned. In this context, “next” does not necessarily mean as Figure 35 ​The next layer in the depth sequence shown is not the next layer to be scanned according to the treatment plan. As mentioned above, the next layer does not necessarily have to be a layer in depth sequential relative to the previously scanned layers. In this example, the next layer can be reached by moving the particle beam across both plates 3801 and 3802. Because plate 3801 has already started moving, plate 3801 can be in place, or will be closer to being in place than if plate 3801 had not yet started moving, to begin the next layer scanning operation.

[0251] refer to Figure 40 and Figure 41 For example, the particle beam can then move across the combined plates 3801 and 3802 from one point toward the starting position (reverse direction) or from one point toward the ending position (forward direction). In this regard, in exemplary operation, each plate of the energy degrader moves from the starting position 4000 to the ending position 4001. In some embodiments, the scanning system can begin scanning the particle beam across the combined plates at a position close to the starting position and proceed toward a point close to the ending position (the corresponding point is determined based on the treatment plan). This is called a forward scan. In some embodiments, the scanning system can begin scanning the particle beam at a point close to the ending position and proceed toward a point close to the starting position (again, the corresponding point is determined based on the treatment plan). This is called a reverse scan. The scanning direction can be specified in the treatment plan and can be based on any suitable factors, such as the position of the plates, the state of the beam, etc.

[0252] As an example, if the board is properly positioned, scanning can be performed in the forward direction (e.g., towards the end position) and then in the reverse direction (e.g., towards the start position). However, in some cases, such as Figure 40 As shown, after scanning plate 3802, for example, when the plate has reached the endpoint position 4001, the following plate 3801 may not yet be in the proper position to scan through the two plates in the reverse direction. In some cases, waiting for the following plate 3801 to reach the proper position for the reverse scan may take more time than repositioning the beam closer to the starting position to scan towards the endpoint position. Accordingly, in this case, the particle beam is repositioned towards the starting position 4000 at the appropriate point 4003 and the scan through the two plates proceeds in the forward direction of arrow 3803, while plate 3801 continues to move towards the endpoint position 4001 (plate 3802 has stopped moving at this point). Again, because plate 3801 is already in place in the beam field, there is no need to wait for the plate to be properly positioned to begin the scan through the two plates. Furthermore, while the scan is being performed, plate 3801 continues to move towards the endpoint position 4001 in the direction of arrow 3803. Plate 3802 may be stationary at this time.

[0253] In some cases, such as Figure 41As shown, after scanning plate 3802, the following plate 3801 can be in position, or such a position can be reachable at the appropriate time, to scan through both plates in the reverse direction (the direction of arrow 4100). Accordingly, in these cases, the scan can proceed in the reverse direction, and plate 3801 can reverse its direction of movement. As the particle beam scans toward the starting position, one or both of plates 3801 and / or 3802 can be retracted, i.e., moved toward the starting position, so that the differently configured plates can be moved into the beam field for the next scan. In Figure 41 In the example shown, both plates are retracted; however, this need not be the case.

[0254] In the example of FIG. 39, the particle beam 3804 is scanned in the forward direction (the direction of arrow 3803) across both plates 3801 and 3802. As shown, the particle beam 3804 is scanned across both plates 3801 and 3802 to produce a particle beam 3805 having the appropriate energy. As shown, the particle beam 3804 is scanned across both plates 3801 and 3802 to produce a particle beam 3805 having the appropriate energy. Figure 40 and Figure 41 In the example of FIG. 39, the particle beam 3804 is scanned in the forward direction (the direction of arrow 3803) across both plates 3801 and 3802. As shown, the particle beam 3804 is scanned across both plates 3801 and 3802 to produce a particle beam 3805 having the appropriate energy. As shown, the particle beam 3804 is scanned across both plates 3801 and 3802 to produce a particle beam 3805 having the appropriate energy. Figure 42 In the example operation, the two (or more) plates 3801, 3802 can begin moving simultaneously in the particle beam field from their starting positions 4000 toward their end positions 4001. During the plate movement, the particle beam can move across the plates in the forward direction (indicated by arrow 3803), thereby passing the particle beam through both plate 3801 and plate 3802 to produce a particle beam 3805 having the appropriate energy. Referring to Figures 44 to 46 After the plates reach the end positions 4001, the particle beam can be scanned in the opposite direction (indicated by arrow 4301) from which the plates (such as plate 3802) were first retracted toward the starting positions 4000. That is, as shown, plate 3802 is first retracted so that the particle beam moves across only plate 3801. As shown, plate 3801 can also be retracted as the particle beam moves across plate 3801. The scanning components and energy degrader can be controlled so that the particle beam follows but does not pass through plate 3802 during its movement in the direction of arrow 4301, thereby passing the particle beam through only plate 3801 to produce a particle beam 3799 having the appropriate energy.

[0255] As described herein, any appropriate number (e.g., one, two, or more) of plates can be moved across the beam field while the particle beam is scanned in the forward or reverse direction across the irradiation target. The number and order of the plates and the direction of scanning can be specified appropriately in the treatment plan. Additionally, as described herein, different plates can have different thicknesses. The plate thickness can affect how the plates are moved.

[0256] The movement of the plates can be sequenced so that the particle beam is not turned off during treatment, or so that the particle beam turn-off time is reduced. For example, the speed at which the particle beam is scanned, the thickness of the plates, and the movement of the plates can be chosen so that a reverse scan is performed immediately or quickly after a forward scan during treatment. For example, referring to Figure 45 , an example energy degrader includes a single thickness ("1X") plate 4402 and a double thickness ("2X") plate 4401, which can be moved into the treatment field simultaneously in a forward direction 4404, and as the particle beam is scanned in the forward direction 4404 during the plate movement, the beam 4405 can pass through both together to produce an energy-degraded particle beam 4405a. Referring to Figure 46 , after the two plates reach their end position 4407, the 2X plate 4401 can be retracted first (moved in a reverse direction 4409), while the particle beam is scanned in the reverse direction and passes through only the 1X plate 4402 to produce an energy-degraded particle beam 4405b. The 1X plate 4402 can also be moved in the reverse direction as the particle beam is scanned in the reverse direction, as shown. As explained above, the particle beam will be scanned across the beam field and through one or more plates at an appropriate distance from the edge of each plate. Referring to Figure 47 , after the particle beam scan reaches the start position and the plate 4402 is fully retracted, another 2X plate 4410 can be moved into position, and both 2X plates 4401 and 4410 can be moved in the forward direction of arrow 4404 as the particle beam is scanned in the forward direction to produce an energy-degraded particle beam 4405c. The various plates can continue to be sequenced as appropriate until all layers of the treatment target are treated.

[0257] As described above, example embodiments of the energy degrader can contain multiple plates each having a thickness of 2X, as well as single or multiple plates having a thickness of 1X. In embodiments such as these, the plates are sequenced for each layer of the treatment target. For example, as shown in Figure 48 , a 1X plate 4701 can be moved into the beam field with zero, one, or more 2x plates for each odd layer 4702-4705 to be treated by the beam 4700, and moved out of the beam field for even layers 4706-4709 to be treated. As explained herein, the layers in the treatment target can not be treated in sequence, depending on the treatment plan.

[0258] In some embodiments, as noted, all of the plates can have the same thickness. Thus, for example initially, a single plate can be moved into the beam field and the particle beam scanned across the beam field and through the plate during movement of the plate in order to produce a particle beam having an energy level sufficient to reach the appropriate layer. A second plate can begin moving before or after the first plate reaches its end point position, and the particle beam can be scanned across the beam field and through the second plate after its movement beginning near its start point position, while the first plate is left in place. During the scan, the beam passes through the first plate and the second plate, changing its energy accordingly. A third plate can begin moving before or after the second plate reaches its end point position, and the particle beam can be scanned across the beam field and through the third plate after its movement beginning near its start point position, while the first plate and the second plate are left in place (their end point positions). During the scan of the particle beam, the beam passes through the first plate, the second plate, and the third plate, changing its energy accordingly. This process can be repeated using the required number of plates to scan all of the layers of the irradiation target. In this example, the scan can be made in the forward direction. In some embodiments, the scan process can be made in the reverse direction. For example, all of the plates can initially be moved from a start point position to an end point position and scanned in the forward direction during movement. Thereafter, the individual plates can be retracted and the particle beam scanned through the remaining plates, for example in the reverse direction, producing particle beams that hit successively deeper layers of the irradiation target. This process can be repeated until all or an appropriate number of plates have been retracted.

[0259] As noted above, the control of the scanning and energy degrading can be implemented using one or more computing systems. In example embodiments, each plate of the energy degrader contains one or more sensors configured to identify the position of the plate relative to the beam field. Referring to Figure 48 In some embodiments, each plate 4801 contains two sensors 4802, 4803.

[0260] In some embodiments, as Figure 48 shown, the sensors are strip sensors located on the same side of each plate; however, in other embodiments, the number, configuration, and arrangement of the sensors can vary from Figure 34The embodiments shown or described herein differ. In example operation, the sensors are independent; for example, the output of one sensor does not depend on the output of other sensors. Independent sensors provide redundancy and confirm that the plate's position is accurately determined. Each sensor detects the position of the plate on which it is mounted relative to and within the beam field, and relays this position to the (multiple) computational systems that control the operation of the scanning system. Feedback from the sensors during plate movement can be continuous. In some embodiments, the sensor output is a voltage proportional to the plate position; however, other types of sensors can be used, such as sensors that detect motor motion relative to the plate position. The particle therapy control system uses this information to determine the beam placement, as well as the location and time to begin scanning. The (multiple) computational systems can also control the movement of the plate into and out of the beam field. Control can be based on the treatment plan and can be coordinated with the control of the scanning system.

[0261] In some implementations, the board's movement speed can be the same regardless of board thickness, direction of movement (e.g., from start to end or end to start), or position relative to any other board. In some implementations, the board's movement speed can be controlled and varied. For example, in some implementations, the speed of the following board during movement can be different from (e.g., greater than) the speed of the board being scanned. This can, for example, enable the following board to reach the appropriate position within a set time. In some implementations, the board position can be determined or increased based on knowledge of the board's speed, its initial position, and the time it began moving. For example, the expected board position can be calculated based on knowledge of the board's speed, its initial position, and the time it began moving. In some implementations, because the board moves in coordination with the beam's movement during scanning, the board only needs to move as fast as the beam moves. In some cases, this coordinated movement of the beam and board can reduce noise and mechanical wear on the energy degrader compared to known degraders that move the board as fast as possible.

[0262] As described above, the particles in the beam have a Gaussian distribution. In some embodiments, passing through one or more plates can lead to further beam divergence. For example, refer to... Figure 34The aperture 3404 can be located between the energy degrader and the irradiation target (e.g., a patient). The aperture trims the spot near the edge of the irradiation target, for example, blocking a portion of the particle beam, to provide a sharp edge to the beam and protect surrounding (untreated) tissue from the particle beam. For example, a beam-blocking material of the aperture can be placed between a portion of the beam and healthy tissue to block the beam from being applied to the healthy tissue. In some embodiments, the aperture can be dynamically controlled to change shape and thereby adapt to the shape of the irradiation target. Examples of apertures that can be used are described in U.S. Patent Application No. 14 / 937,048, filed November 10, 2015, entitled "Adaptive Aperture," which is incorporated by reference herein. Examples of structures that can be used to block a portion of the particle beam to provide a sharp edge to the beam and protect surrounding (untreated) tissue from the particle beam are also referred to herein as collimators, and can be used in ​ embodiments of the system 3000.

[0263] The energy degraders described herein and the elements used in their operation are not limited to plates. Rather, any appropriate structure can be used to affect the energy of the particle beam. In embodiments that employ plates or similar structures, each plate or structure need not have a uniform thickness, for example, there can be at least some variation in thickness across one or more individual plates. If such plates are of a suitable size (e.g., small enough), the plates can be moved across the beam field so that the beam passes through one or more plates and through different portions of those plates having different thicknesses in order to treat different layers of the target.

[0264] The gantry, patient support, active beam shaping elements (including, for example, apertures, energy degraders, and scanning), and the synchrocyclotron are coordinated by appropriate treatment control electronics (not shown) to conduct a treatment session.

[0265] The control of the particle therapy systems described herein and their various features can be implemented using hardware or a combination of hardware and software. For example, a system similar to that described herein can include various controllers and / or processing devices located at various points. A central computer can coordinate the operation between the various controllers or processing devices. The central computer, controllers, and processing devices can execute various software routines to implement the control and coordination of testing and calibration.

[0266] The system operation can be controlled, at least in part, using one or more computer program products, for example, one or more computer programs tangibly embodied in one or more non-transitory machine- readable media, for execution by, or to control the operation of, one or more data processing apparatus, e.g., a programmable processor, a computer, multiple computers and / or programmable logic components.

[0267] A computer program can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and are interconnected by a network.

[0268] Actions associated with implementing all or part of the operations of the particle therapy systems described herein can be performed by one or more programmable processors executing one or more computer programs to perform the functions described herein. All or part of the operations can be implemented using special purpose logic circuitry, e.g., an FPGA (field programmable gate array) and / or an ASIC (application specific integrated circuit).

[0269] As examples, processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only storage area or a random access storage area or both. The elements of a computer (including a server) include one or more processors for executing instructions and one or more storage area devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or in

[0270] Any “electrical connection” used herein can imply a direct physical connection, or a connection that includes intermediate components but still allows electrical signals to flow between the connected components. Unless otherwise specified, any “connection” to an electrical circuit referred to herein that allows signal(s) to pass through is an electrical connection, and is not necessarily a direct physical connection regardless of whether the “connection” is modified with the word “electrical.”

[0271] Any two of the foregoing embodiments can be used in suitable combination in a suitable particle accelerator (e.g., a synchrocyclotron). Likewise, individual features of any two or more of the foregoing embodiments can be used in suitable combination.

[0272] Elements of different implementations described herein can be combined to form other implementations not specifically set forth herein. Elements can be left out of the processes, systems, devices, etc. described herein without adversely affecting their operation. Various separate elements can be combined into one or more individual elements to perform the functions described herein.

[0273] The example implementations described herein are not limited to use with or use with the example particle therapy systems described herein. Rather, the example implementations can be used in any appropriate system that directs accelerated particles toward an output.

[0274] Other implementations not specifically described herein are also within the scope of the following claims.

Claims

1. A particle therapy system, comprising: Particle accelerators are used to output particle beams. as well as An energy degrader, which is controllable to allow the particle beam to pass through to the irradiated target, wherein at least a portion of the energy degrader is controllable to move during the passage of the particle beam to the irradiated target. The energy degrader includes multiple plates that are controllable to move and includes a first plate and a second plate. The first plate is controllable to move in a first direction during the movement of the particle beam, and the second plate is controllable to move in the first direction. The second plate is controllable to begin moving at a certain point in time after the first plate has started moving, while the first plate is moving and the particle beam continues to move, and the second plate is controllable to partially overlap with and follow the first plate during the movement of the first plate in a first direction, such that the particle beam does not pass through the second plate during at least a portion of the movement of the first and second plates.

2. The particle therapy system of claim 1, further comprising: A scanner that is controllable to move the particle beam in one or more dimensions relative to the irradiated target; At least one of the energy degrader or the scanner is controllable such that during at least a partial movement of the first plate and the second plate, the particle beam passes through the first plate but not through the second plate.

3. The particle therapy system of claim 1, further comprising: A scanner that is controllable to control the movement of the particle beam relative to the irradiated target in one or more dimensions; At least one of the energy degrader or the scanner is controllable such that the particle beam passes through both the first plate and the second plate during at least a partial movement of the first plate and the second plate.

4. The particle therapy system of claim 1, further comprising: A scanner that is controllable to move the particle beam in one or more dimensions relative to the irradiated target; The scanner is controllable such that the movement of the particle beam across the plates is restricted to a predetermined distance from the edge of the plate.

5. The particle therapy system of claim 1, wherein, During the movement of the first and second plates, the first and second plates are controllable to move from a starting position to an ending position; and The particle beam is controllable to move from a position toward the endpoint position, such that the particle beam passes through both the first plate and the second plate, or only through the first plate.

6. The particle therapy system of claim 1, wherein, During the movement of the first plate and the second plate, the first plate and the second plate are controllable to move from the starting position to the ending position; and The particle beam is controllable to move from one position toward the starting position, such that the particle beam passes through both the first plate and the second plate, or only through the first plate.

7. The particle therapy system of claim 1, wherein the energy degrader comprises a plurality of plates; and The plurality of plates includes one or more first plates and one or more second plates, the one or more first plates and the one or more second plates being controllable to move relative to the particle beam, and the thickness of each of the one or more first plates being less than the thickness of each of the one or more second plates.

8. The particle therapy system of claim 7, wherein the thickness of each of the one or more first plates is a portion of the thickness of each of the one or more second plates.

9. The particle therapy system of claim 8, wherein the thickness of each of the one or more first plates is half the thickness of each of the one or more second plates.

10. The particle therapy system of claim 1, wherein controlling the movement of the plurality of plates includes sequencing the movement of the plurality of plates such that each of the multiple layers of the irradiated target is subjected to the particle beam.

11. The particle therapy system of claim 10, wherein control of the movement of the plurality of plates includes ordering the movement of the plurality of plates such that multiple layers of the irradiated target are processed with the particle beam out of order.

12. The particle therapy system of claim 1, wherein controlling the movement of the plurality of plates includes sequencing the movement of the plurality of plates such that the energy of the particle beam corresponds to the position of each layer in the multilayer of the irradiated target.

13. The particle therapy system of claim 1, further comprising: An orifice, which is controllable to shape the speckle of the particle beam, is located between the irradiated target and the energy degrader.

14. The particle therapy system of claim 1, wherein the size of each of the plurality of plates is smaller than the size of the irradiation field.

15. The particle therapy system of claim 1, wherein the particle accelerator comprises a synchrotron accelerator to generate a particle beam; and The system includes an orifice between the energy degrader and the irradiated target, the orifice being controllable to trim the particle beam before it reaches the irradiated target.

16. The particle therapy system of claim 15, further comprising: An outer gantry on which the synchrotron is mounted, the outer gantry being configured to move the synchrotron at least partially around the irradiated target; as well as An inner gantry, which is swept within the outer gantry, includes a nozzle on which the energy degrader is mounted, and the inner gantry is configured to move the energy degrader based on the movement of the outer gantry.

17. The particle therapy system of claim 15, wherein the movement of the particle beam across the plates of the plurality of plates is restricted to movement at a distance from the edge of the plate.

18. An energy degrader, comprising: A first structure comprising a beam energy absorbing material controllable by a control system to move through at least a portion of a beam field in a first direction when a radiation beam is incident on a surface of the first structure and as the radiation beam moves through the surface of the first structure, wherein the movement of the radiation beam through the surface of the first structure is at least partially in the first direction, and A second structure comprising a beam energy absorbing material controllable by a control system to move through at least a portion of the beam field when a radiation beam is incident on the surface of the first structure. The second structure is controllable to follow and guide the first structure in a first direction such that the radiation beam does not pass through either the first or second structure during the movement of at least a portion of the first and second structures.

19. The energy degrader according to claim 18, wherein, The first structure includes a first plate and the second structure includes a second plate.

20. The energy degrader according to claim 18, wherein, The size of the energy degrader is smaller than that of the beam field.

21. The energy degrader according to claim 18, wherein, The first structure includes a first sensor to detect the position of the first structure relative to and within the beam field, and to relay the position of the first structure to the control system.

22. The energy degrader according to claim 21, wherein, The second structure includes a second sensor to detect the position of the second structure relative to and within the beam field, and to relay the position of the second structure to the control system.

23. The energy degrader according to claim 18, wherein, The first and second structures can be controlled by the control system to move at different speeds.

24. The energy degrader according to claim 18, wherein, The first and second structures can be controlled by the control system to move between a starting position and an ending position, the starting position corresponding to a point where the radiation beam moves at least partially in a first direction, and the ending position corresponding to a point where the radiation beam stops moving.

25. The energy degrader according to claim 18, wherein, The first structure includes a plate having a first thickness, and the second structure includes a plate having a second thickness, wherein the first thickness and the second thickness are different.

26. The energy degrader of claim 18 further comprises a plurality of plates, the plurality of plates including one or more first plates of a first structure and one or more second plates of a second structure, the one or more first plates and the one or more second plates being controllable by a control system to move relative to a radiation beam, each of the one or more first plates having a thickness less than the thickness of each of the one or more second plates.

27. The energy degrader according to claim 18, wherein, Controlling the movement of multiple plates via the control system includes sequencing the movement of the multiple plates so that each of the multiple layers of the irradiated target is affected by the radiation beam.

28. The energy degrader according to claim 27, wherein, Controlling the movement of multiple plates via the control system includes sequencing the movement of the multiple plates so that multiple layers of the irradiated target are processed non-sequentially by the radiation beam.

29. An energy degrader, comprising: A first structure includes a beam energy absorbing material that can be controlled by a control system to move at least a portion of the beam field. and A second structure includes a beam energy absorbing material that can be controlled by a control system to move at least a portion of the beam field. The first and second structures are controllable to move at the same time and in the same direction when at least partially overlapping, such that at a first time, the irradiated target associated with the beam field is subjected to radiation passing through one of the first or second structures, but not both, and at a second time, the irradiated target is subjected to radiation passing through both the first and second structures.

30. The energy degrader according to claim 29, wherein, At least a portion of the first and second structures overlap.

31. The energy degrader according to claim 29, wherein, The first structure includes a first plate and the second structure includes a second plate.

32. The energy degrader according to claim 29, wherein, The surface area of ​​the energy degrader is less than 1 / 4 of the area of ​​the beam field.

33. The energy degrader according to claim 29, wherein, The first structure includes a first sensor to detect the position of the first structure relative to and within the beam field, and to relay the position of the first structure to the control system. The second structure includes a second sensor to detect the position of the second structure relative to and within the beam field, and to relay the position of the second structure to the control system.

34. The energy degrader according to claim 29, wherein, At least one of the first or second structures can be controlled by the control system to move in the same direction at the same speed as the particle beam including the radiation.

35. The energy degrader according to claim 29, wherein, The first structure includes a first plate, the second structure includes a second plate, and when the irradiated target is subjected to radiation that passes through the first plate but not the second plate, the second plate can be controlled by a control system to move at a speed greater than that of the first plate for at least a portion of the time.

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