Applicable opening

Abstract

The present invention relates to an adaptive aperture for use with a particle therapy system. An exemplary particle therapy system includes a particle accelerator for outputting a particle beam having a spot size, a scanning system for the particle accelerator for scanning the particle beam in two dimensions over at least a portion of a treatment region of an irradiation target, and an adaptive aperture between the scanning system and the irradiation target. The adaptive aperture includes a structure movable relative to the irradiation target to approximate the shape and trim a portion of the treatment region. The portion of the treatment region has a size based on the area of ​​the spot size.

Description

Technical Field

[0001] The present disclosure generally relates to an adaptive aperture for use, for example, with a particle beam therapy system.

Background Art

[0002] A particle beam therapy system uses an accelerator to generate a particle beam for treating afflictions such as tumors. During operation, particles are accelerated along a trajectory within a cavity in the presence of a magnetic field and are extracted from the cavity through an extraction channel. A magnetic field regenerator generates magnetic field bumps near the outside of the cavity to distort the pitch and angle of some of the trajectories such that these trajectories undergo a precession motion toward the extraction channel and ultimately enter the extraction channel. A beam of particles exits the extraction channel.

[0003] A scanning system is located on the down-beam side of the beam from the extraction channel. In this context, "down-beam side" means closer to the irradiation target (here, with respect to the extraction channel). The scanning system moves the particle beam across at least a portion of the irradiation target, exposing various portions of the irradiation target to the particle beam. For example, in order to treat a tumor, the particle beam can be "scanned" over different cross-sectional layers of the tumor.

[0004] The particle beam can damage healthy tissue adjacent to the irradiation target. To limit the exposure of healthy tissue to the particle beam, a structure including an aperture can be used. For example, this structure, or a part thereof, can be placed between the particle beam and the healthy tissue, thereby preventing the exposure of the healthy tissue to the particle beam.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention provides an adaptive aperture for use with a particle beam therapy system.

Means for Solving the Problems

[0006] An exemplary particle therapy system comprises a particle accelerator for outputting a particle beam having a spot size, a scanning system for the particle accelerator for scanning at least a portion of the treatment area of ​​an irradiation target with the particle beam in two dimensions, and an adaptive aperture between the scanning system and the irradiation target. The adaptive aperture comprises a structure movable relative to the irradiation target to approximate the shape and trim a portion of the treatment area. The portion of the treatment area has a size based on the area of ​​the spot size. An exemplary particle therapy system may include one or more of the following features, individually or in combination:

[0007] The size of a portion of the treatment area may be approximately the same as a spot-size area, a two-spot-size area, a three-spot-size area, a four-spot-size area, or a five-spot-size area. The portion of the treatment area may be less than the entire treatment area. The structure may be movable relative to the irradiation target to approximate a curved shape, at least partially.

[0008] The adaptive aperture may comprise a primary carriage coupled to the structure to move the structure relative to the irradiation target in a direction perpendicular to the irradiation target, a first motor for controlling the movement of the primary carriage, a secondary carriage coupled to the primary carriage and to the structure to move the structure horizontally relative to the irradiation target, and one or more secondary motors for controlling the horizontal movement of the structure. Horizontal movement may include movement in and out of the treatment area. The secondary carriage may comprise a first secondary carriage coupled to the primary carriage to move at least some of the structure relative to the irradiation target, and a second secondary carriage coupled to the primary carriage to move at least some of the structure relative to the irradiation target. At least one of the secondary carriages may be rotatable relative to the primary carriage, and / or the entire adaptive aperture may be rotatable relative to the irradiation target.

[0009] In a particle beam therapy system, at least some structures movable by a first secondary carriage have flat edges, and at least some structures movable by a second secondary carriage have flat edges. The first secondary carriage may be mounted on and movable along a curved track, and the second secondary carriage may be mounted on and movable along a curved track.

[0010] The structure comprises leaves, at least some of which have a width different from the height of the other leaves. At least some of which may have a width that is three times or more the height of the other leaves. The leaves may contain a metal such as nickel or tungsten.

[0011] A particle beam therapy system may include a memory for storing executable instructions and one or more processing devices for constructing an adaptive aperture by executing instructions and controlling the movement of structures.

[0012] The movement of the structure can be controlled based on the operation of the scanning system. The scanning system can be controlled to scan the treatment area multiple times with the particle beam. The movement of the structure can be controlled so that the configuration of the structure changes for different scans of the particle beam over at least a portion of the treatment area. For different scans of the particle beam over the treatment area, the configuration of the structure can be shifted vertically relative to the treatment area. For different scans of the particle beam over the treatment area, the configuration of the structure can be shifted horizontally relative to the treatment area.

[0013] The structure may comprise 5 to 50 leaves. The adaptive aperture may comprise a primary carriage to which the leaves are connected so as to move the leaves relative to the irradiation target perpendicular to the irradiation target; a first motor for controlling the movement of the primary carriage; a first secondary carriage coupled to the primary carriage and to which a first set of leaves is attached; a second secondary carriage coupled to the primary carriage and to which a second set of leaves is attached; and one or more second motors for controlling the movement of the leaves in the first and second primary carriages.

[0014] The particle accelerator may be a cynchrocyclotron. The particle beam therapy system may comprise a cynchrocyclotron, a scanning system, and a gantry fitted with an adaptive aperture, the gantry being rotatable around the patient to reach the treatment area. The cynchrocyclotron may comprise a voltage source configured to periodically sweep an RF voltage over a certain frequency range for applying an RF voltage to a cavity to accelerate particles from a particle source; a coil for receiving a current having one of a plurality of values ​​and generating a magnetic field corresponding to the current, the magnetic field moving particles along an orbit in the cavity with energy corresponding to the current, and the magnetic field being at least 4 Tesla; and an extraction channel for receiving particles from the cavity and outputting the particles received from the cavity to a scanning system, the particles being output from the cavity having energy corresponding to the current. The cynchrocyclotron may be configured to allow the current to be set to one of a plurality of values, each of which may correspond to a different energy at which particles are output from the cavity. The energy of the particles emitted from the cavity can be variable within a range of approximately 100 MeV to approximately 300 MeV. The voltage source may be configured to sweep the RF voltage across different frequency ranges, each of which corresponds to a different energy at which the particles are emitted from the cavity.

[0015] A synchrocyclotron may comprise a particle source having two parts separated in an acceleration region and located within a cavity for holding an ionizing plasma; a voltage source configured to periodically sweep an RF voltage over a certain frequency range for applying an RF voltage to the cavity to accelerate particles from the ionizing plasma in the separated region of the particle source; a coil for receiving a current and generating a magnetic field corresponding to the current, the magnetic field causing particles to move along an orbit within the cavity with energy corresponding to the current, and the magnetic field being at least 4 Tesla; at least one magnetic pole piece including a ferromagnetic material defining the shape of the cavity; and a drawer channel for receiving particles from the cavity and outputting the received particles to a scanning system. The energy of the particles output from the cavity may be in the range of about 100 MeV to about 300 MeV. The voltage source may be configured to sweep an RF voltage over different frequency ranges, each different frequency range corresponding to each different energy of the particles output from the cavity.

[0016] The scanning system may comprise: a scanning magnet that influences the direction of a particle beam and is controllable based on a current passing through the scanning magnet to move the particle beam across a treatment area in two directions; a degrader located downstream of the magnet with respect to the synchrocyclotron for altering the energy of the particle beam before moving it across the cross-section of the irradiation target; and a control system for (i) controlling the current passing through the scanning magnet to deliver a dose of charged particles by causing a continuous movement of the beam across at least a portion of the irradiation target; (ii) storing information identifying the position and the dose delivered for the location where the particle beam delivers the dose; (iii) comparing the cumulative dose delivered at each position with the target cumulative dose; and (iv) controlling the current to move the beam to deliver an additional dose to a particular position if the cumulative dose at a particular position does not match the target cumulative dose. The adaptive aperture may be located downstream of the scanning system with respect to the synchrocyclotron.

[0017] Adaptive apertures may be configured to mimic patient-specific apertures. The structure comprises leaves, at least some of which have a different shape from the other leaves, and at least some of which have a curved shape. The leaves may have flat edges. Adaptive apertures may comprise a primary carriage and a secondary carriage to which the leaves are mounted to position the leaves relative to the irradiation target, the secondary carriage being mounted on the primary carriage, and the primary carriage being for positioning the secondary carriage. The particle beam therapy system may include curved tracks that the primary and secondary carriages follow as they move.

[0018] Also described herein are adaptive apertures comprising a structure movable relative to an irradiation target to approximate the shape and trim a portion of the radiotherapy area of ​​the irradiation target, the portion of the radiotherapy area having a size based on the area of ​​the spot size. Exemplary adaptive apertures may include, either alone or in combination, the appropriate features described in this abstract of the invention.

[0019] An exemplary adaptive aperture may comprise a relatively small number of motors, cables, leaves, and other hardware, all of which may be relatively small in size. As such, an adaptive aperture may be smaller than at least some other types of adaptive apertures used in particle beam therapy. Due to its small size, the adaptive aperture can be mounted at the end of the treatment nozzle and thus brought closer to the patient without substantially interfering with the treatment. Furthermore, due to its proximity to the patient and its size, the edges of the particle beam affecting the patient may be sharper than those produced by systems placed further away from the patient. For example, an adaptive aperture may be positioned as close as 4 cm from the patient. In one embodiment, an adaptive aperture may occupy a space of 36 cm × 50 cm in area and 10 cm in depth.

[0020] By combining two or more of the features described in this disclosure, including those described in the Summary of the Invention section, embodiments not specifically described herein can be formed.

[0021] The various systems described herein, or the control of a portion thereof, can be implemented via a computer program product stored on one or more non-transitory machine-readable storage media and containing instructions executable on one or more processing devices (e.g., programmed logic circuits such as microprocessors, application specific integrated circuits, field programmable gate arrays, or the like). The systems described herein, or a portion thereof, can be implemented as an apparatus, method, or electronic system that can include one or more processing devices and computer memory for storing executable instructions for implementing the described functions.

[0022] The details of one or more embodiments are described in the accompanying drawings and the following description. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

Brief Description of the Drawings

[0023] [Figure 1] A perspective view of an exemplary adaptive aperture leaf that can be used with the exemplary adaptive apertures described herein. [Figure 2] A top view of an adaptive aperture leaf positioned with respect to the treatment area of an irradiation target. [Figure 3] A perspective view of an exemplary adaptive aperture. [Figure 4] A side view of an exemplary adaptive aperture. [Figure 5] A perspective view of an exemplary adaptive aperture with components shown transparently to show its interior. [Figure 6] A top view of an exemplary control structure used to move a leaf into and out of the treatment area of an irradiation target. [Figure 7] Perspective view of an exemplary adaptive aperture having a curved leaf. [Figure 8] Cross-sectional view of an exemplary synchrocyclotron for use in a particle beam therapy system. [Figure 9] Cross-sectional view of an exemplary synchrocyclotron for use in a particle beam therapy system. [Figure 10] Side view of an exemplary scanning system. [Figure 11] Perspective view of components of an exemplary scanning system. [Figure 12] Front view of an exemplary magnet for use in a scanning system of the type shown in FIGS. 10 and 11. [Figure 13] Perspective view of an exemplary magnet for use in a scanning system of the type shown in FIGS. 10 and 11. [Figure 14] Perspective view of an exemplary energy degrader (range modulator) for use in a scanning system of the type shown in FIGS. 10 and 11. [Figure 15] Perspective view of a process for moving the leaves of an energy degrader within the path of a particle beam. [Figure 16] Perspective view of an adaptive aperture positioned with respect to a patient during particle therapy treatment. [Figure 17] Flowchart showing an exemplary process for performing a raster scan that can be executed using the hardware of FIGS. 10 to 15. [Figure 18] Top view showing an exemplary cross-section of an irradiation target and a radiation scanning path. [Figure 19] Perspective view of an exemplary treatment system. [Figure 20] Exploded perspective view of components of an exemplary synchrocyclotron for use in a particle beam therapy system. [Figure 21] Cross-sectional view of an exemplary synchrocyclotron. [Figure 22] Perspective view of an exemplary synchrocyclotron. [Figure 23] This is a cross-sectional view of an exemplary ion source for use in a synchrocyclotron. [Figure 24] This is a perspective view of an exemplary D-leaf and an exemplary D-D for use in a synchrocyclotron. [Figure 25] This figure shows a patient positioned within an exemplary internal gantry of an exemplary particle beam therapy system in a treatment room. [Figure 26] This is a conceptual diagram of an exemplary particle beam therapy system that can utilize a variable energy particle accelerator. [Figure 27] This is an exploded perspective view of an exemplary magnet system that may be used in a variable energy particle accelerator. [Figure 28] This is an illustrative graph showing the energy and current as they respond to variations in the magnetic field and distance within the particle accelerator. [Figure 29] This is a side view of an exemplary structure for sweeping a voltage over a D-leaf across a fixed frequency range for each energy level of a particle beam, and changing the frequency range as the particle beam energy changes. [Figure 30] This is a top view of an adaptive aperture leaf on a carriage mounted on a track that is curved relative to the direction of the particle beam. [Figure 31] This is a top view of an adaptive aperture leaf positioned relative to the treatment area of ​​the irradiation target. [Modes for carrying out the invention]

[0024] Similar reference symbols in various drawings indicate similar elements.

[0025] This specification describes exemplary embodiments of adaptive apertures that can be used to control the range of radiation, such as proton or ion beams. In this regard, an adaptive aperture is a structure that can be controlled to allow some radiation to enter a patient and to block some radiation from entering the patient. Typically, the incoming radiation is directed to the irradiation target to be treated, while the blocked radiation, if not blocked, would hit healthy tissue and potentially damage it. In operation, the adaptive aperture is placed in the radiation path between the radiation source and the irradiation target, forming an opening of appropriate size and shape to allow some radiation to pass through the opening in the irradiation target, while the rest of the structure is controlled to block some radiation from reaching adjacent tissue. Adaptive apertures may be used in any suitable radiotherapy system and are not limited to use with any particular type of system. This specification describes examples of systems in which adaptive apertures may be used.

[0026] In some embodiments, adaptive apertures typically include flat structures, referred to as “plates” or “leaves,” which are controllable to move within a “beam” or “treatment” area to block a portion of the radiation and allow a portion of the radiation to pass through. The leaves are controllable to form an aperture of an appropriate size and shape for the current treatment. In some embodiments, the leaves are held on two carriages, facing each other and the treatment area. The leaves are controllable to move within and out of the treatment area to form an aperture (or opening) through which a particle beam passes to treat the patient’s area. The leaves forming the aperture also block radiation from entering tissue adjacent to the aperture covered by the leaves (e.g., healthy tissue). In this context, the covering step includes the step of the leaves blocking the particle beam.

[0027] Figure 1 shows an example of a leaf 40 that may be used in an adaptive aperture, but the adaptive aperture is not limited to being used with this type of leaf. The leaf height 50 is aligned with the beamline (e.g., the direction of the particle beam). The leaf length 52 is aligned with the operating direction into and out of the treatment area and is based on the size of the field, or a portion thereof, that the system can treat. The size of the field corresponds to the treatment area that the beam can impact. The leaf width 53 is the direction in which multiple leaves stack when operating. Generally, the more leaves used, the higher the resolution of the aperture that can be formed, including in the case of curved boundaries.

[0028] In Figure 1, the leaf 40 includes a tongue and groove component 55 along its side, which is configured to reduce leakage between leaves when multiple such leaves are stacked. In this example, the curved end 56 of the leaf 40 is configured to maintain a surface in contact with the beam in all arrangements within the treatment area. However, as also described herein, the end of each leaf may be flat and not curved.

[0029] In some embodiments, the adaptive aperture leaf has sufficient height to block at least the maximum beam energy (e.g., the maximum energy of the particle beam output by the system). In some embodiments, the adaptive aperture leaf has height to block energies below the maximum beam energy for the reasons described below. In some embodiments, the adaptive aperture leaf has a length that is not shown over the entire treatment area, but rather over the area of ​​a single beam spot or multiple beam spots. In this context, “beam spot” refers to the cross-sectional area of ​​the particle beam.

[0030] In one example, a particle beam therapy system may be configured to treat a tumor having a cross-section that can be fitted within a square area of ​​20 cm x 20 cm. In this example, each leaf in the adaptive aperture may be about 2 cm long, which is roughly sufficient to block particles in half of one beam spot. As noted, the adaptive aperture includes a set of leaves facing each other. Thus, leaves from each set can be controlled to cover an entire single beam spot if necessary, thereby preventing radiation from passing through. The leaves can also be controlled to form an aperture through which some or all of the radiation from a single beam spot can pass.

[0031] During operation, the adaptive aperture moves along with the beam as it scans the radiation target, and is configured to follow the beam's movement during the scan. In this example, the adaptive aperture may be configured to move approximately 20 cm to cover an entire 20 cm × 20 cm area. As described above, the adaptive aperture may be configured to use a sufficient number of leaves to cover (or "trim") one beam spot and, in some cases, a small amount of extra area (e.g., 5%, 10%, 15%, or 20%).

[0032] Figure 2 shows an exemplary embodiment of the adaptive aperture 700. The adaptive aperture 700 comprises a leaf 701 having sufficient height to obstruct or prevent the passage of radiation of a given energy and made of a metal such as nickel, brass, tungsten, or other metals sufficient to obstruct or prevent the passage of radiation of a given energy. For example, in some systems, the particle accelerator is configured to generate a particle beam having a maximum energy of 100 MeV to 300 MeV. In such a system, the leaf may be fabricated to prevent the passage of beams having energies such as 100 MeV, 150 MeV, 200 MeV, 250 MeV, 300 MeV, etc.

[0033] Leaf 701 is mounted on a carriage to control the movement of the irradiation target relative to the treatment area, such as a cross-sectional layer of the patient's tumor. The movement is controlled so that leaf 701 covers some portion of the treatment area 704, thereby preventing radiation from hitting those portions during treatment, while leaving other portions of the treatment area exposed to radiation. In the exemplary embodiment shown in Figure 2, there are 14 leaves in total, 7 on the left and 7 on the right. In some embodiments, there may be a different number of leaves, for example, 10 leaves in total, 5 on the left and 5 on the right; 12 leaves in total, 6 on the left and 6 on the right; and so on.

[0034] Adaptive apertures can be used with an appropriate type of radiotherapy system. In one exemplary embodiment, the radiotherapy system is a proton therapy system. As described herein, the exemplary proton therapy system scans a proton beam across a treatment area of ​​the irradiation target to destroy malignant tissue. During scanning, the particle beam moves from one end of the treatment area to the other, irradiating the entire treatment area with radiation. In one exemplary embodiment, the particle beam is pulsed. Because the particle beam is pulsed, the affected portion of the treatment area constitutes a series of spots, one for each pulse that hits the treatment area. Depending on the size of the beam, some areas may remain untreated as a result. Consequently, it may be beneficial to scan the same treatment area multiple times to ensure that the entire area is treated. Each successive scan may be offset from other scans to ensure that all areas are covered. One example of this type of scanning is called pencil beam scanning, and repeated scans are referred to as drawing or redrawing the treatment area.

[0035] The irradiation target is typically a three-dimensional structure. Therefore, as described herein, the irradiation target is treated layer by layer (or simply "layers"). That is, once a layer of the irradiation target is treated, another layer is treated, and so on, until the entire target is treated. Different layers of the irradiation target are treated by changing the energy levels of the particle beam. That is, particle beams of different energy levels collide with different layers of the irradiation target, and the higher the energy level, the deeper the layers inside the irradiation target relative to the particle beam source. Therefore, during treatment, the energy levels of the particle beam are changed to reach and thereby treat different layers of the irradiation target.

[0036] Figure 2 shows a leaf 701 configured to allow radiation to collide with a portion of the layer (e.g., the treatment area) while preventing radiation from colliding with other portions of the layer (e.g., healthy tissue). In Figure 1, alignment 707 represents the center of the beam spot to be delivered while the proton beam is scanning across the treatment area 704. Circle 708 represents the treatment boundary beyond which the delivered radiation is intended not to cross. Beam spots close to this boundary (e.g., within one standard deviation of the particle beam profile) are adjacent to healthy tissue. These are the spots that are trimmed (i.e., blocked) by appropriately configuring and positioning the leaf on the adaptive aperture. An example of a beam spot to be trimmed is beam spot 711, with its center at alignment 706. As illustrated, leaf 701 is configured to block the portion of beam spot 711 that extends beyond circle 708.

[0037] In one exemplary embodiment, each of the two separate carriages has five leaves approximately 5 mm wide and two leaves approximately 20 mm wide. In some embodiments, each of the two separate carriages has seven leaves, two of which have a width three times or more the width of each of the other five leaves. Other embodiments may include different numbers, sizes, and configurations of leaves, as well as different numbers and configurations of carriages. For example, some embodiments may include between 5 and 50 leaves per carriage, or 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 (or more) leaves per carriage.

[0038] The carriage can move both horizontally and vertically, as described herein. The leaf is also horizontally movable relative to each carriage, both in and out of the treatment area. In this way, the leaf can be configured to approximate the shape of the treatment boundary in an area near the area being treated (e.g., circle 711 or a portion thereof in this example).

[0039] The leaf can move vertically and / or horizontally between different scans of the particle beam so that it is in the appropriate position when the beam is delivered to a particular area. The leaf does not necessarily need to move for every scan pass, but instead may move to a position appropriate to the area. In some cases, for example, for a spot inside the treatment area, radiotherapy can proceed without trimming provided by the adaptive aperture.

[0040] Figure 31 shows another example of a leaf 1400, which is part of an adaptive aperture configured to trim a radiation spot 1401 centered on arrangement 1402. In this example, there are seven leaves on each of the two sides of the adaptive aperture (supported by corresponding carriages). Each side of the leaf includes two leaves that are wider than the other five, but the adaptive aperture is not limited to this configuration. In this case, spot 1401 has a radius of 2.5 sigma that defines an 8 mm Gaussian radiation spot.

[0041] Figures 3, 4, and 5 show exemplary embodiments of carriages 713, 714, and 715 configured to hold and move the leaf described above in both vertical and horizontal directions relative to the treatment target. As illustrated, vertical movement includes movement in the Cartesian Z direction 717, and horizontal movement includes movement in the Cartesian X direction 718 (the Cartesian Y direction is either inside or outside the page of Figure 4). Figures 4 and 5 show portions of the carriage housing as if they were transparent to show the internal components of the housing, but the housing is not actually transparent.

[0042] Carriage 713 is referred to herein as the primary carriage, and carriages 714 and 715 are referred herein as secondary carriages. The secondary carriages 714 and 715 are coupled to the primary carriage 713 as shown in Figures 3 to 5. In this example, the secondary carriages 714 and 715 each have a housing that is fixed to the primary carriage 715 via corresponding members 718 and 719. In this example, the primary carriage 713 is movable vertically relative to the irradiation target and relative to the particle accelerator along the track 720. Vertical movement of the primary carriage 713 also moves the secondary carriages vertically. In some embodiments, the secondary carriages move vertically simultaneously. In some embodiments, the vertical movement of each secondary carriage is independent of the vertical movement of the other secondary carriages.

[0043] As shown in Figures 3 to 5, each secondary carriage 714, 715 is connected to corresponding rods 722, 723, along which the secondary carriage moves. More specifically, in this example, motor 725 drives secondary carriage 714 to move along rod 722 toward secondary carriage 715 or away from secondary carriage. Similarly, in this example, motor 726 drives secondary carriage 715 to move along rod 723 toward secondary carriage 714 or away from secondary carriage. Control over the movement of the primary and secondary carriages is implemented to position the leaf relative to the irradiation target, as described herein. In addition, the leaf itself is also configured to move into and out of the carriage, as also described herein.

[0044] As shown in Figure 5, the motor 730 drives the vertical movement of the primary carriage 713. For example, as shown in Figure 3, the lead screw 731 is coupled to the housing 732, which holds motors 725, 726 that drive the corresponding secondary carriages 714, 715. The lead screw 731 is coupled to the motor 730 and driven vertically by the motor 730. That is, the motor 730 drives the lead screw 731 vertically, either toward the irradiation target or toward the irradiation target. Since the lead screw 731 is fixed to the housing 732, this movement also moves the housing 732 and therefore the secondary carriages 714, 715 along the track 720, either toward the irradiation target or toward the irradiation target.

[0045] In this exemplary embodiment, as noted, seven leaves 735, 736 are mounted on each secondary carriage 714, 715. Each secondary carriage may be configured to move its leaves horizontally into or out of the treatment area. Individual leaves on each secondary carriage may be independently movable in the X direction relative to other leaves on the same secondary carriage. In some embodiments, leaves may also be configured to move in the Y direction. Furthermore, leaves on secondary carriage 714 may be independently movable from leaves on other secondary carriages 715. These independent movements of leaves on secondary carriages, along with the vertical movement enabled by the primary carriages, allow the leaves to move in various configurations. As a result, the leaves can be shaped to conform to treatment areas that are randomly shaped both horizontally and vertically. The size and shape of the leaves can be varied to result in different conformations.

[0046] Leafs can be made from suitable materials that prevent or block the transmission of radiation. The type of radiation used may indicate what materials are used within the leaf. For example, if the radiation is X-rays, the leaf may be made from lead. In the examples described herein, the radiation is a proton or ion beam. Therefore, different types of metals or other materials may be used for these leaves. For example, leaves may be made from nickel, tungsten, lead, brass, steel, iron, or a suitable combination thereof. The height of each leaf may determine the degree to which the leaf blocks the transmission of radiation.

[0047] In some embodiments, the leaves may have the same height, but in other embodiments, some of these leaves may have a different height from the other leaves. For example, in Figures 2 to 5, each leaf has a height of 5 mm. However, any suitable height may be used. For example, leaves 735 and 736 may have any of the following heights: 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, etc. (or other heights). The leaves may have any combination of the aforementioned heights. In addition, each leaf may have a different height from one or more other leaves in the leaf system.

[0048] Leafs of the same or varying heights may be stacked to block radiation transmission. In some embodiments, shorter leaves (e.g., leaves with less height) may be used in conjunction with longer leaves. In some embodiments, the leaves are tall enough to completely block particle beams of maximum beam energy. In some embodiments, the leaves are tall enough to block particle beams below maximum beam energy (but not the maximum energy particle beam). For example, a proton therapy system may have the ability to deliver a beam with an energy of 230 MeV that can treat to a depth of 32 cm in the patient's body, but in some embodiments, the adaptive aperture can only block protons of at most 175 MeV that can treat to depths of 20 cm or less. In such cases, smaller beam-stopping materials may be used, e.g., 2.1 cm of tungsten instead of 3.3 cm, or 3.3 cm of nickel instead of 5.2 cm. In this example, the proton therapy system can still treat to depths greater than 20 cm, but the adaptive aperture is not used for such treatments. This can be considered acceptable in some situations, as deeper treatment sites do not offer the same benefit as the particle beam collimation provided by adaptive apertures. In other words, in some treatment scenarios, shallow, low-energy treatments are where adaptive apertures are most effective, and there may be engineering advantages to reducing the amount of material in the leaf. Therefore, in some exemplary embodiments, shorter leaves are used, and the adaptive aperture is limited to shallow treatments below the maximum energy.

[0049] In the embodiments shown in Figures 2 to 5, the leaves have a semi-rectangular shape and have approximately the same surface area when viewed from the side. In some embodiments, this is not necessarily the case. For example, the leaves may have a different shape than those shown. Exemplary shapes include, but are not limited to, circular, curved, oval, square, and triangular shapes. Furthermore, individual leaves may have a different shape from other leaves within the same carriage or different carriages. For example, one carriage may contain both rectangular and curved leaves.

[0050] In some embodiments, the leaves are tall enough to not only completely stop the particle beam at the maximum expected proton energy (e.g., 3.3 cm of tungsten or, for example, 5.2 cm of nickel at 230 MeV), but also to have enough extra material to prevent proton transmission between the leaves. This material may have a tongue and groove structure as shown in Figure 1, or a similar configuration. The leaf ends may have curved or tapered surfaces and be configured to extend the penumbra resulting from various divergences of the proton beam.

[0051] In some embodiments, there may be multiple primary carriages and corresponding motors and rails. For example, a first primary carriage may control the vertical movement of a first secondary carriage, and a second primary carriage may control the vertical movement of a second secondary carriage. Thus, in such embodiments, the two secondary carriages may be moved independently in the vertical direction, if desired. In any case, the primary carriages may be computer-controlled. For example, executable instructions are stored in computer memory (e.g., one or more non-temporary machine-readable storage media) and executed by one or more processing devices to control the movement. The control may be performed with or without user input during treatment.

[0052] As described, each secondary carriage 714, 715 is equipped with a corresponding motor for controlling the horizontal carriage movement, as described above. In some embodiments, there may be one motor per leaf, but in other embodiments, a single motor may control all leaves. The motor may be mounted on the corresponding secondary carriage. As a result, the motor moves vertically together with the corresponding secondary carriage. As noted, the motor controls the movement of the leaf within each carriage. The leaf is mounted on an actuator that allows movement in two directions. In the examples in Figures 2 to 5, the leaf is each part of an integrated leaf. Referring to the example in Figure 6, the mechanism allows individual leaves to move into or out of a treatment area, or out of an integrated leaf, which has each carriage moving into or out of the treatment area.

[0053] In some embodiments, all leaves on a single carriage are independently movable. Figure 6 shows the movement mechanism for leaf 735a, which is part of a secondary carriage. Each leaf within each secondary carriage may have a configuration and movement mechanism similar to, or identical to, the leaf and movement mechanism in Figure 6.

[0054] In the example shown in Figure 6, the moving mechanism comprises a leaf stick 735b, a lead screw nut 735c, a lead screw 735d, a thrust bearing assembly 735e, a coupling 735f, a motor 735g, a bearing block 735h, a sleeve bearing pin 735i, a sleeve bearing 735j, and a motor mount block 735k. During operation, the motor shaft rotates the lead screw through the coupling. This causes the lead screw nut to advance or retract depending on the direction of rotation of the screw. The lead screw nut is fixed to the leaf assembly, and therefore the leaf moves forward or backward as the motor rotates (entering or exiting the beam path). The sleeve bearing pin slides along the sleeve bearing, which is fixed to the leaf and constrained within a bearing block supporting the entire assembly. This bearing block houses the bearing and provides space for the motor assembly for all leaves on the carriage.

[0055] As described, adaptive openings are used to trim each layer of scanning treatment by different opening shapes, thereby enabling three-dimensional field shaping techniques such as lamination. However, one embodiment of an adaptive opening may be configured to mimic either a machined patient-specific structure or a multi-lobe collimator.

[0056] In this regard, existing treatment planning systems (TPS) typically include the ability to calculate the shape of a fixed brass opening intended to be uniformly applied throughout the treatment volume. The TPS may also include instructions to indicate or configure an adaptive opening shape for a target. A computer program can interpret the opening shape from either a continuous opening curve or a set of fixed multi-lobe collimator leaf positions and translate that shape into a series of dynamic leaf positions for an adaptive opening associated with the radiation therapy spot being delivered. Thus, existing TPS functionality may be utilized, making it possible to make adaptive openings compatible with existing TPS software with relatively few modifications.

[0057] Another exemplary technique that can improve marginal isometricity and is made possible by adaptive apertures is the possibility that the therapeutic dose to the same therapeutic area of ​​a layer may be delivered in several passes or draws. Redraws as described herein is a technique used in scanning proton therapy in which several particle beam passes are used to deliver a dose to a therapeutic area in order to uniformly disperse radiation delivered over a long timescale compared to patient movements such as breathing. There are other reasons as well. Some exemplary reasons include that dynamic dose management can adjust the input in each pulse to deliver the exact total dose, that there are safety limits to the input in a single pulse, and that the required dynamic range of the dose may exceed the capacity of the particle accelerator.

[0058] If a spot within the irradiation volume is drawn multiple times during treatment (e.g., across multiple scans), the isoangularity of the adaptive aperture to the outer edge of the irradiation target can be improved by slightly shifting the leaves (e.g., at a sub-millimeter level) vertically, horizontally, or both vertically and horizontally between each drawing (e.g., each scan of the particle beam across the entire treatment area). In this way, edges that may be slightly jagged due to the finite size of individual leaves can be smoothed to obtain a better approximation of the intended aperture curve.

[0059] By adding rotational degrees of freedom, the ability of the adaptive aperture to conform to a rotating target can be improved. For example, the entire assembly in Figures 3 to 5 may be configured to rotate in a plane perpendicular to the beam direction, in a plane parallel to the beam direction, or in a combination thereof. In some embodiments, each individual secondary carriage 714, 715 may be configured to rotate independently in the same plane. In this way, the adaptive aperture can have greater flexibility to conform to complex shapes that are not in an ideal orientation. In some embodiments, both the primary carriage and each secondary carriage may be rotatable.

[0060] In the exemplary embodiments described above, each leaf is operated independently so that any shape can be traced by the leaf configuration. However, such flexibility may not be necessary to obtain acceptable edge isometricity. Leaves may be mechanically constrained by their ability to achieve only a finite number of configurations. For example, leaves may be limited to arrangement configurations that result in vertical lines, front diagonal shapes, rear diagonal shapes, concave shapes, convex shapes, or any other achievable shape. Thus, flexibility may come at the expense of mechanical simplicity. Leaves may be operated using cam timing leaves through a single remote motor instead of four motors mounted on a secondary carriage. In some embodiments, the discrete shapes of the leaves may be machined from sectors of a wheel that rotates in place as needed. To reduce the number of motors, feedbacks, controllers, and associated wiring, assemblies with a single motor to achieve the discrete leaf configuration may be used.

[0061] Figure 7 shows an exemplary embodiment of an adaptive opening having curved leaves 750 that are rotatable relative to a shaft 751. In the example of Figure 7, all leaves are actuated by a single motor located at the top of the vertical shaft 751. The shape and orientation of the leaf cams are selected to achieve different leaf configurations for different rotation angles of the main drive shaft.

[0062] Another possible advantage of adaptive openings is that they can collimate edges that are entirely within the field. When a treatment plan requires a volume to completely enclose a volume to be protected, for example, a tumor completely enclosing the spinal cord, a single machined structure would typically have to block a portion of the treatment volume to block radiation into the protected volume. Adaptive openings can treat such fields using a series of leaf positions. For example, adaptive openings can be reconfigured dynamically and during treatment to protect areas requiring protection while allowing treatment on areas requiring treatment.

[0063] In some cases, better beam performance (penumbra or edge sharpness) is obtained as a result when the particle beam is in contact with the surface of the leaf edge. However, since the beam is effectively emitted from a single point source, the angle at which it passes through the plane of the adaptive aperture changes as the beam moves away from the center of the field. For this reason, as shown in Figure 1, the leaf often has a curved edge, and therefore the edge can be positioned so that it is always in contact with the particle beam. In an exemplary embodiment of the adaptive aperture, the track on which both the primary and secondary carriages move is curved so that the leaf edge can be used instead of a curved leaf edge, and is flat but remains in contact with the particle beam.

[0064] Figure 30 shows an exemplary embodiment of a curved track 1420. In the example of Figure 30, the particle beam 1421 is emitted from a source 1422, which may be a particle accelerator such as a synchrocyclotron as described herein. The particle beam 1422 may scan a field 1423 and may be in one range in arrangement 1425 and in another range in arrangement 1426. A carriage holding leaves 1428 and 1429 is mounted on a curved track 1420 so that the leaves 1428 and 1429 can move toward or away from each other. In this example, the leaves have straight ends (or "front ends") 1431, 1431, in contrast to the curved ends 56 in Figure 1. By employing a curved track, the particle beam may remain in contact with, or substantially in contact with, the straight ends throughout the scanning field 1423. Keeping the particle beam in contact with its edges can be advantageous in that it allows the trimming provided by the adaptive aperture to be consistent across the entire range of the beam field.

[0065] In summary, in some embodiments, the adaptive aperture trims only a small portion of the treatment area at a time, e.g., less than the entire treatment area, and approximately equal to 1-spot size, 2-spot size, 3-spot size, 4-spot size, 5-spot size, etc. Thus, in some embodiments, the adaptive aperture may be small enough to trim a single spot at a time and large enough to trim several spots at one location rather than the entire field without moving. Thus, the adaptive aperture may be configured to move around and within the field as the beam scans. That is, in some embodiments, the adaptive aperture follows the beam as it scans, and its configuration and reconfiguration may be synchronized with the scan and with the pulses produced by the beam (e.g., different beam pulses and / or locations will result in different reconfigurations). By not using leaves large enough to trim the entire treatment area, the adaptive aperture can be smaller and therefore can be brought closer to the patient with little or no interference from other devices. In some embodiments, none of the leaves of the adaptive aperture have a single direction that spans the entire maximum treatment area. In some embodiments, each individual leaf is movable in two directions within the treatment area, and the device is mounted on a gantry (for example, in the context of a particle beam therapy system as described herein) to rotate on one or more axes, and is expandable toward and away from the isogonal point.

[0066] Described herein are examples of particle accelerator systems, such as proton or ion therapy systems, which may employ the adaptive apertures shown in Figures 1 to 7, 30, and 31. An exemplary particle therapy system includes a particle accelerator mounted on a gantry, in this example, a synchrocyclotron. The gantry allows the particle accelerator to rotate around the patient's position, as detailed below, thereby allowing the particle beam from the accelerator to be directed onto any treatment area of ​​the patient. In some embodiments, the gantry is made of steel and has two legs, each mounted to rotate on two bearings located on either side of the patient. The particle accelerator is supported by a steel truss long enough to straddle the treatment area where the patient lies, and the steel truss is mounted at both ends to the rotating legs of the gantry. As the gantry rotates around the patient, the particle accelerator also rotates.

[0067] In one exemplary embodiment, a particle accelerator (e.g., a synchrocyclotron) comprises a cryogenic holding chamber that holds one or more superconducting coils, each for conducting a current that generates a magnetic field (B). In one example, the cryogenic holding chamber uses liquid helium (He) to maintain each coil at a superconducting temperature, e.g., 4° Kelvin (K). A magnetic yoke or smaller pole piece is positioned inside the cryogenic holding chamber and defines the shape of the cavity through which particles are accelerated. Magnetic shims can pass through the magnetic yoke or pole piece and alter the shape and / or magnitude of the magnetic field within the cavity.

[0068] In this exemplary embodiment, the particle accelerator includes a particle source (e.g., a Penning ion gauge--PIG source) to supply a column of ionized plasma to a cavity. Hydrogen gas is ionized to generate the plasma column. A voltage source applies a radio frequency (RF) voltage to the cavity to accelerate pulses of particles from the plasma column into the cavity. The magnetic field within the cavity takes shape to move the particles along trajectories within the cavity. The magnetic field may be, for example, at least 4 Tesla, as described herein.

[0069] As noted, in one example, the particle accelerator is a synchrocyclotron. Therefore, when accelerating particles from a plasma column, the RF voltage is swept over a certain range of frequencies to account for relativistic effects on the particles (e.g., an increase in particle mass). Along with the shape of the cavity, the magnetic field generated by passing current through superconducting coils accelerates the particles accelerated from the plasma column along an orbit within the cavity. In other embodiments, particle accelerators other than synchrocyclotrons may be used. For example, cyclotrons, synchrotrons, and linear accelerators may be alternatives to the synchrocyclotron described herein.

[0070] In an exemplary synchrocyclotron, a magnetic field regenerator ("regenerator") is located near the outside of the cavity (e.g., its inner edge) and modifies the existing magnetic field inside the cavity, thereby altering the position (e.g., pitch and angle) of the continuous trajectories of particles accelerated from the plasma column, ultimately leading the particles out through a cryogenic holding chamber into an extraction channel. The regenerator increases the magnetic field at a certain point within the cavity (e.g., creating a magnetic field "bump" of about 2 Tesla in a region of the cavity), thereby causing each continuous trajectory of the particles at that point to precess outward toward the entrance point of the extraction channel until it reaches the extraction channel. The extraction channel receives the particles accelerated from the plasma column out of the cavity and outputs the received particles as a particle beam out of the cavity.

[0071] The superconducting ("main") coil can generate relatively high magnetic fields. The magnetic field generated by the main coil can range from 4T to 20T or higher. For example, the main coils are 4.0T, 4.1T, 4.2T, 4.3T, 4.4T, 4.5T, 4.6T, 4.7T, 4.8T, 4.9T, 5.0T, 5.1T, 5.2T, 5.3T, 5.4T, 5.5T, 5.6T, 5.7T, 5.8T, 5.9T, 6.0T, 6 .1T, 6.2T, 6.3T, 6.4T, 6.5T, 6.6T, 6.7T, 6.8T, 6.9T, 7.0T, 7.1T, 7.2T , 7.3T, 7.4T, 7.5T, 7.6T, 7.7T, 7.8T, 7.9T, 8.0T, 8.1T, 8.2T, 8.3T, 8. 4T, 8.5T, 8.6T, 8.7T, 8.8T, 8.9T, 9.0T, 9.1T, 9.2T, 9.3T, 9.4T, 9.5T, 9.6T, 9.7T, 9.8T, 9.9T, 10.0T, 10.1T, 10.2T, 10.3T, 10.4T, 10.5T, 1 0.6T, 10.7T, 10.8T, 10.9T, 11.0T, 11.1T, 11.2T, 11.3T, 11.4T, 11.5T , 11.6T, 11.7T, 11.8T, 11.9T, 12.0T, 12.1T, 12.2T, 12.3T, 12.4T, 12. 5T, 12.6T, 12.7T, 12.8T, 12.9T, 13.0T, 13.1T, 13.2T, 13.3T, 13.4T, 13.5T, 13.6T, 13.7T, 13.8T, 13.9T, 14.0T, 14.1T, 14.2T, 14.3T, 14.4 T. 16.4T, 16.5T, 16.6T, 16.7T, 16.8T, 16.9T, 17.0T, 17.1T, 17.2T, 17.3T, 17.4T, 17.5T, 17.6T, 17.7T, 17.8T, 17.9T, 18.0T, 18.1T, 18.2T, 1 8.3T, 18.4T, 18.5T, 18.6T, 18.7T, 18.8T, 18.9T, 19.0T, 19.1T, 19.2T , 19.3T, 19.4T, 19.5T, 19.6T, 19.7T, 19.8T, 19.9T, 20.0T, 20.1T, 20.It can be used to generate magnetic fields of one or more magnitudes, or greater than, 2T, 20.3T, 20.4T, 20.5T, 20.6T, 20.7T, 20.8T, 20.9T, or higher. Furthermore, the main coil can be used to generate magnetic fields in the range of 4T to 20T (or higher or lower), not specifically listed above.

[0072] In some embodiments, such as those shown in Figures 8 and 9, a large ferromagnetic magnetic yoke acts as a feedback to the stray magnetic field generated by the superconducting coil. For example, in some embodiments, the superconducting magnet can generate a relatively high magnetic field, for example, 4T or more, resulting in a considerable stray magnetic field. In some systems, such as those shown in Figures 8 and 9, a relatively large ferromagnetic feedback yoke 100 is used as a feedback to the magnetic field generated by the superconducting coil. A magnetic shield surrounds the yoke. Together, the feedback yoke and shield dissipate the stray magnetic field, thereby reducing the probability that the stray magnetic field will adversely affect the operation of the accelerator.

[0073] In some embodiments, the feedback yoke and shield may be replaced or enhanced by an active feedback system. An exemplary active feedback system comprises one or more active feedback coils that carry current in the opposite direction to the current flowing through the main superconducting coil. In some exemplary embodiments, there is an active feedback coil for each superconducting coil, for example, two active feedback coils—one for each superconducting coil—(referred to as “main coils”). Each active feedback coil may be a superconducting coil that concentrically surrounds the outside of the corresponding main superconducting coil.

[0074] The current passes through the active feedback coil in the opposite direction to the current passing through the main coil. This causes the current passing through the active feedback coil to generate a magnetic field with opposite polarity to the magnetic field generated by the main coil. As a result, the magnetic field generated by the active feedback coil can dissipate at least a portion of the relatively strong stray magnetic field resulting from the corresponding main coil. In some embodiments, each active feedback can be used to generate magnetic fields from 2.5T to 12T or higher. For example, the magnetic fields can be 2.5T, 2.6T, 2.7T, 2.8T, 2.9T, 3.0T, 3.1T, 3.2T, 3.3T, 3.4T, 3.5T, 3.6T, 3.7T, 3.8T, 3.9T, 4.0T, 4.1T, 4.2T, 4.3T, 4.4T, 4.5T, 4.6T, 4.7T, 4.8T, 4.9T. T, 5.0T, 5.1T, 5.2T, 5.3T, 5.4T, 5.5T, 5.6T, 5.7T, 5.8T, 5.9T, 6.0T, 6.1T, 6.2 T, 6.3T, 6.4T, 6.5T, 6.6T, 6.7T, 6.8T, 6.9T, 7.0T, 7.1T, 7.2T, 7.3T, 7.4T, 7.5T , 7.6T, 7.7T, 7.8T, 7.9T, 8.0T, 8.1T, 8.2T, 8.3T, 8.4T, 8.5T, 8.6T, 8.7T, 8.8T , 8.9T, 9.0T, 9.1T, 9.2T, 9.3T, 9.4T, 9.5T, 9.6T, 9.7T, 9.8T, 9.9T, 10.0T, 10. The magnetic fields may be 1T, 10.2T, 10.3T, 10.4T, 10.5T, 10.6T, 10.7T, 10.8T, 10.9T, 11.0T, 11.1T, 11.2T, 11.3T, 11.4T, 11.5T, 11.6T, 11.7T, 11.8T, 11.9T, 12.0T, or higher. Furthermore, active feedback coils may be used to generate magnetic fields in the range of 2.5T to 12T (or higher or lower) not specifically listed above.

[0075] As shown in Figure 10, an exemplary scanning system 106 is located at the output of the extraction channel 102 of the particle accelerator 105 (which may have the configuration shown in Figures 8 and 9), and may be used to scan the particle beam over at least a portion of the irradiation target. Figure 11 also shows examples of components of the scanning system. These include, but are not limited to, a scanning magnet 108, an ionization chamber 109, and an energy degrader 110. Other components that may be incorporated into the scanning system, not shown in Figure 11, include, for example, one or more scatterers for changing the beam spot size. The exemplary scanning system, including its components, may be mounted on the gantry and may move with the particle accelerator when the gantry moves.

[0076] In exemplary operation, the scanning magnet 108 is controllable in two dimensions (e.g., XY dimensions of Cartesian coordinates), thereby guiding the particle beam to the treatment area (e.g., cross-section) of the irradiation target. The ionization chamber 109 detects the beam dose and feeds this information back to the control system to adjust the beam movement. The energy degrader 110 is controllable by moving material (e.g., one or more individual plates) into and out of the path of the particle beam to change the energy of the particle beam and, therefore, the depth to which the particle beam penetrates the irradiation target. In this way, the energy degrader selects layers of the irradiation target at each depth by scanning in two directions.

[0077] Figures 12 and 13 show an exemplary scanning magnet 108. In this exemplary embodiment, the scanning magnet 108 comprises two coils 111 that control the particle beam movement in the X direction and two coils 112 that control the particle beam movement in the Y direction. Control is achieved, in some embodiments, by changing the current through one or both sets of coils, thereby changing the generated magnetic field. By appropriately changing the magnetic field, the particle beam can be moved in the X and / or Y directions over the irradiation target. In some embodiments, the scanning magnet is not physically movable relative to the particle accelerator. In other embodiments, the scanning magnet may be movable relative to the particle accelerator (in addition to movement provided by the gantry, e.g.). In some embodiments, the scanning magnet may be controllable to move the particle beam continuously, so that the particle beam moves uninterruptedly over at least a portion, and possibly all, of the layers of the irradiation target or a portion thereof (e.g., the treatment area) being scanned. In other embodiments, the scanning magnet is controllable at intervals or at specific times. In some embodiments, different scanning magnets may be used to control all or partial movement of the particle beam in the X and / or Y directions.

[0078] In some embodiments, the scanning magnet 108 may have an air core. In other embodiments, the scanning magnet 108 may have an air ferromagnetic (e.g., iron) core. Generally, an air-core magnet comprises a magnetic coil around a core that is a non-ferromagnetic material, such as air. For example, an air-core magnet may comprise a self-supporting coil surrounding air. In some embodiments, an air-core magnet may comprise a coil wound around an insulator, such as ceramic or plastic, which may or may not contain air.

[0079] In some cases, air cores may have advantages over ferromagnetic cores. For example, the amount a particle beam moves (e.g., deflects) in the X and / or Y directions is determined, at least in part, by the amount of current applied to the magnet (referred to as "magnet current"). A scanning magnet typically has a movement (or deflection) range, which is the range over which the magnet moves the beam. At the upper and lower limits of this range, such as at the edges, larger amounts of current are applied to the scanning magnet to achieve relatively high amounts of beam deflection. Some types of scanning magnets with ferromagnetic cores may saturate at these upper and lower limits, resulting in a nonlinear relationship between the current and the movement of the magnet. That is, the amount of deflection caused by the magnet may not be linearly proportional to the amount of current applied to the magnet. This nonlinearity can make it difficult, in some cases, to determine and / or set certain beam positions using the magnet current. Therefore, when scanning magnets with ferromagnetic cores are used, some calibration and / or correction may be required to compensate for the nonlinearity described above.

[0080] In contrast, scanning magnets with air cores may not saturate as much as scanning magnets with ferromagnetic cores. For example, air core magnets may not saturate at all, or their saturation may be less than that of magnets with ferromagnetic cores. As a result, the relationship between current and magnet movement becomes more linear, especially at the upper and lower limits of the range, and in at least some cases, the determination of beam placement based on magnet current can be more accurate. Such increased linearity can also allow for more precise beam movement, especially at the upper and lower limits of the range. That is, since the relationship between current and beam movement is generally more linear over a larger range when air core scanning magnets are used, beam movement may be more easily reproducible using air core scanning magnets. This can be advantageous because layers at each depth of the irradiation target may require multiple scans, each contributing a percentage of the total cumulative radiation dose. The precision with which multiple doses can be delivered to the same area, as can be achieved through the use of air core scanning magnets, can affect the effectiveness of treatment.

[0081] The relationship between current and magnet movement may be more linear within an air-core magnet, but in some cases, air-core magnets may be more susceptible to stray magnetic fields than magnets with ferromagnetic cores. These stray magnetic fields can affect the scanning magnet when it is moving due to the gantry. Therefore, in some embodiments using an air-core scanning magnet, the current applied to the scanning magnet to move the beam may be calibrated to take into account the position of the scanning magnet relative to the patient (or, correspondingly, the position of the gantry, since the position of the gantry corresponds to the position of the scanning magnet relative to the patient). For example, the behavior of the scanning magnet may be determined for different rotational positions (angles) of the gantry, for example, by increasing or decreasing some applied current based on the rotational position, and corrected if necessary.

[0082] In some embodiments, the scanning magnet may have a core made of both air and a ferromagnetic material (e.g., iron). In such embodiments, the amount and composition of air and ferromagnetic material in the core may be determined considering the aforementioned factors.

[0083] In some embodiments, the current sensor 118 may be connected to the scanning magnet 108 or associated with it in some other way. For example, the current sensor may communicate with the scanning magnet, but may not be connected. In some embodiments, the current sensor samples the current applied to the magnet, which may include the current to a coil for controlling a beam scanning in the X direction and / or the current to a coil for controlling a beam scanning in the Y direction. The current sensor may sample the current passing through the magnet at a rate corresponding to the occurrence of pulses in the particle beam, or at a rate exceeding the rate at which pulses occur in the particle beam. In the latter case, the sample identifying the magnet current correlates with the detection of pulses by an ionization chamber, as described below. For example, the number of times pulses are detected using an ionization chamber (described below) correlates in time with the sample from the current sensor, and the number of these pulses can identify the current in the magnet coil. Thus, by using the magnet current, it may be possible to determine the placement of each pulse and, therefore, the dose of particles delivered on the irradiation target (e.g., on layers at each depth of the irradiation target). The arrangement of layers at each depth can be determined based on the location of energy degraders in the beam path (e.g., the number of plates).

[0084] During operation, the magnitude (e.g., value) of the magnet current, along with the dose (e.g., intensity), may be stored for each configuration to which the dose is delivered. A computer system, which may be located on or off the accelerator and may include memory and one or more processing devices, may correlate the magnet current with coordinates within the irradiation target, and these coordinates may be stored along with the dose. For example, configurations may be identified by the number of layers per depth and orthogonal XY coordinates, or by orthogonal XYZ coordinates (where layers correspond to the Z coordinate). In some embodiments, both the magnitude of the magnet current and the coordinate configuration may be stored along with the dose in each configuration. This information may be stored in memory, either on or off the accelerator. As described in more detail herein, this information may be used during scanning to apply multiple doses to the same configuration to achieve a target cumulative dose.

[0085] In some embodiments, the ionization chamber 109 detects the dose (e.g., one or more individual doses) applied to a position on the irradiation target by the particle beam by detecting the number of ion pairs formed in the gas produced by the incident radiation. The number of ion pairs corresponds to the dose delivered by the particle beam. This information is fed back to a computer system and stored in memory along with the time it takes for the dose to be delivered. This information may be correlated with and stored in relation to the arrangement in which the dose was delivered and / or the magnitude of the magnet current at that time, as described above.

[0086] As described in more detail below, in some embodiments, the scanning system operates in an open loop, in which case the particle beam moves freely and uninterruptedly over the irradiation target, irradiating substantially the entire target with radiation. As radiation is delivered, dose measurements performed by the particle therapy control system record (or store) the amount of radiation for each placement and information corresponding to the placement to which the radiation was delivered. The placement to which the radiation was delivered may be recorded as coordinates or as one or more magnet current values, and the amount of radiation delivered may be recorded as a dose in gray units. Since the system operates in an open loop, radiation delivery is not synchronized with the operation of the particle accelerator (e.g., its RF cycle). However, dose measurements may be synchronized with the operation of the particle accelerator. More specifically, dose measurements record each delivered dose and its placement as the dose is delivered (i.e., as close to the point of delivery as possible, subject to the limitations of the technology). Since the dose is delivered in sync with the operation of the accelerator (e.g., one pulse is delivered per RF cycle), in some embodiments, the dose meter recording the dose and placement operates in sync with, or substantially sync with, the delivery of the radiation dose to the target, and therefore in sync with the operation of the particle accelerator, such as its RF cycle.

[0087] Figure 14 shows a range modulator 115, which is an exemplary embodiment of the energy degrader 110. In some embodiments, such as those shown in Figure 14, the range modulator comprises a series of plates 116. These plates can be made from one or more of the following materials: carbon, beryllium, or other materials with low atomic numbers. However, other materials may be used instead of, or in addition to, these exemplary materials.

[0088] One or more of these plates can move either into or out of the beam path, thereby influencing the energy of the particle beam and, consequently, the penetration depth of the particle beam into the irradiation target. For example, the more plates that move into the particle beam path, the more energy is absorbed by the plates, and the less energy the particle beam acquires. Conversely, the fewer plates that move into the particle beam path, the less energy is absorbed by the plates, and the more energy the particle beam acquires. Higher energy particle beams typically penetrate deeper into the irradiation target than lower energy particle beams. In this context, "higher" and "lower" are relative terms and do not have any specific numerical implications.

[0089] The plates are physically moved in and out of the path of the particle beam. For example, as shown in Figure 15, plate 116a moves along the direction of arrow 117 between its position in and out of the path of the particle beam. The plates are computer-controlled. Generally, the number of plates moving in the path of the particle beam corresponds to the depth to which the irradiation target should be scanned. For example, the irradiation target may be divided into several cross-sections or layers of varying depths, with each cross-section or layer corresponding to an irradiation depth. One or more plates of the range adjuster can move in and out of the beam path to the irradiation target, thereby obtaining the appropriate energy to irradiate each of the cross-sections or layers of the irradiation target. The range adjuster may remain stationary relative to the particle beam during scanning of a portion of the irradiation target (e.g., a cross-section), except for the plates moving in and out of the path of the particle beam. Alternatively, the range adjusters in Figures 14 and 15 may be replaced, at least sometimes, with a range adjuster that follows the movement of the particle beam, thereby allowing the use of smaller plates.

[0090] In embodiments using the range adjustment devices described above, the number of plates moving within the beam path determines / sets the layers at each depth of the irradiation target to be scanned. For example, if two plates move within the beam path, the layers will be shallower than if one plate moves within the beam path or if no plates move at all. The layers can be identified and stored in memory based on the number of plates moving within the beam path. In some embodiments, the plates may have different heights. In such embodiments, the varying plate heights also affect which layers should be scanned (e.g., how deep the particle beam penetrates the target).

[0091] In some embodiments, the particle accelerator may be a variable-energy particle accelerator. In exemplary systems using a variable-energy particle accelerator, the energy levels of the particle beam can be controlled by the particle accelerator, so the type of energy degrader described herein is less likely to be needed. For example, in some systems employing a variable-energy particle accelerator, an energy degrader may not be required. In some systems employing a variable-energy particle accelerator, an energy degrader may still be used to change the beam energy levels.

[0092] In some embodiments, a treatment plan is created before treating the irradiation target. The treatment plan may be stored in memory accessible from a computer system that controls the operation of the particle beam therapy system. The treatment plan may contain information on how the radiation therapy should be performed by the particle beam therapy system. For example, the treatment plan may specify how scanning should be performed on a particular irradiation target. In some embodiments, the treatment plan specifies that a raster scan should be performed. A raster scan includes steps that cause a continuous movement of the particle beam over the irradiation target. For example, a scanning magnet constantly moves to scan (e.g., move) the particle beam over the irradiation target, causing a continuous movement of the particle beam over at least a portion of the layers of the irradiation target. The movement may be continuous across the entire layer of the irradiation target or over only a portion of the layer. In some embodiments, the beam may move at a constant speed along all or part of the layers of the irradiation target. In some embodiments, the speed at which the beam moves along all or part of the layers of the irradiation target may be variable. For example, the particle beam may move faster within the layers than at the edges of the layers. The speed of movement may be specified in the treatment plan.

[0093] In some embodiments, the treatment plan may also specify the target cumulative dose of radiation (particle beam) to be applied to various locations on the irradiated target layer. The dose is cumulative in the sense that it can be achieved through the application of one or more doses of the particle beam. For example, the same arrangement on the irradiated target (e.g., XYZ space) may be irradiated 10 times, with each irradiation being 10% of the target cumulative dose in order to achieve the target cumulative dose. In some embodiments, the treatment plan does not need to specify the dose for each arrangement, the arrangement, or the number of times an arrangement should be irradiated. That is, this information may be omitted from the treatment plan in some embodiments. Rather, in some embodiments, the intensity of the particle beam may be preset to deliver a specific dose of radiation for each irradiation instance. The particle beam can then be scanned on the irradiated target layer in an open-loop manner without requiring feedback to move to the next arrangement. As the particle beam is scanned, the beam arrangement is determined, and the corresponding dose at that arrangement is determined. This determination may be made almost simultaneously with the scanning and delivery (i.e., as close to the delivery time as possible, even if there are limitations of the technology). The cumulative dose at the placement, including the current dose and the dose already delivered during the current treatment, is compared to the target cumulative dose from the treatment plan. If these two do not match, an additional dose may be applied to the placement during subsequent scans. The number of scans the placement undergoes does not need to be predetermined, as it is not always known exactly how much radiation is delivered to the placement with each scan. Similarly, the exact amount of radiation delivered to the placement with each scan may vary, so the exact amount of radiation per scan is not necessarily predetermined. Therefore, in some embodiments, such information does not need to be included in the treatment plan.

[0094] In some embodiments, the treatment plan may include one or more patterns over which the particle beam may be scanned layer by layer. The treatment plan may also specify the number of plates of the energy degrader to achieve a particular energy level / layer. Other embodiments may include additional or alternative information to that specified above.

[0095] In some embodiments, the overall treatment plan for the irradiation target may include different treatment plans for different cross-sections (layers) of the irradiation target. These treatment plans for different cross-sections may include the same or different information, as given above.

[0096] The scanning system includes adaptive apertures, as shown in Figures 1 to 7, 30, and 31 (or variations thereof), which can be positioned relative to the irradiation target to limit the range of the particle beam, thereby limiting the range of the particle beam. For example, the adaptive aperture may be positioned in the beam path downstream of the energy degrader and before the particle beam strikes the treatment area of ​​the irradiation target. The adaptive aperture can be controlled to allow the particle beam to pass through it and then strike certain parts of the treatment area, while preventing the particle beam from striking other parts of the patient. For example, the adaptive aperture may be controlled to prevent the particle beam from striking healthy tissue or to prevent the particle beam from striking other parts of the irradiation target (e.g., some parts of the target will be more irradiated than others). Figure 16 shows the positioning of an embodiment 770 of the adaptive aperture described herein relative to a patient 771. The direction of the beam 771a is also illustrated.

[0097] As noted above, in some embodiments, scanning is performed in an open-loop manner, which may be implemented using one or more processing devices, such as a computing device that controls the particle beam therapy system. In this example, the open-loop scanning includes the step of moving the particle beam over the irradiation target to irradiate substantially the entire target with radiation. In some embodiments, the movement is not synchronized with the accelerator operation, e.g., the RF frequency, but rather is performed independently of the accelerator operation while the accelerator is operating. For example, the movement of the particle beam may be uninterrupted and independent of the particle accelerator's RF cycle. The uninterrupted movement may be performed over all or part of the layers of the irradiation target. However, as described herein, dose measurement may be synchronized with the delivery of pulses of the particle beam to the irradiation target. In examples where dose measurement is synchronized with the delivery of pulses of the particle beam, dose measurement is also synchronized with the accelerator operation (e.g., the RF frequency used to extract pulses of the particle beam from the ion source plasma column).

[0098] The radiation levels of individual doses of a particle beam (e.g., individual pulses from an accelerator) can be pre-defined. For example, each individual dose may be specified in gray units. The individual dose may be a percentage of the target cumulative dose to be applied to a configuration (e.g., XYZ coordinates) within the irradiation target, or a corresponding percentage. In some embodiments, the individual dose may be 100% of the target cumulative dose, resulting in only one scan being required to deliver a single dose of radiation (e.g., one or more particle pulses) per configuration to the irradiation target. In some embodiments, the individual dose may be less than 100% of the target cumulative dose, resulting in multiple scans of the same configuration being required to deliver multiple doses of radiation to the irradiation target. Individual doses may be appropriate percentages of the target cumulative dose, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or any percentage between these values.

[0099] The scanning magnet current can be controlled according to the treatment plan to scan layers at each depth of the irradiation target. The layers are selected by appropriately positioning one or more energy degraders from a range compensator in the path of the particle beam and / or setting the energy levels of a variable energy particle accelerator. As the layers are scanned, a current sensor samples the current applied to the scanning magnet. The amount of magnet current can be recorded and stored, for example, in memory. If multiple magnets or magnet coils are used, the amount of magnet current can be stored along with the identification of the magnet or coil. In addition, the current may be correlated with coordinates within the irradiation target (e.g., orthogonal XYZ coordinates), and those coordinates may be stored in addition to, or instead of, the corresponding magnet current. As described above, the current sensor may sample the magnet current and correlate the sampling time with the time at which the irradiation dose (e.g., pulse) is delivered.

[0100] In this regard, the ionization chamber 109 can detect the intensity of the dose delivered to the irradiation target when the dose is delivered. The intensity of each dose is recorded (e.g., stored in memory) along with the arrangement of each dose delivered. As noted, the arrangement of each dose delivered can be stored by coordinates, magnet current, or by using some other suitable metric. As stated above, dose measurement, i.e., dose verification, may be synchronized with the delivery of the dose and therefore with the output of the accelerator (corresponding to the RF frequency, as described above). Thus, in some embodiments, each time a dose is delivered, the intensity of that dose is determined almost immediately, and the arrangement to which the dose is applied is determined almost immediately. This information can be stored in one or more tables (e.g., one table per layer or multiple tables per layer) or other suitable computer storage device.

[0101] In some embodiments, the table may be updated as additional doses are delivered. For example, the table may continuously record the dose delivered at each configuration. Thus, if the beam dose is "X" gray, in the first scan pass, the table may record X gray for the configuration. In the second scan pass, the table may record 2X gray, and so on, until the target cumulative dose is reached.

[0102] In this regard, for each configuration, a processing device associated with the accelerator (e.g., a computer system controlling the particle beam therapy system) may compare the cumulative dose from a table as described above with the target cumulative dose. If the cumulative dose matches the target cumulative dose, the treatment for that configuration (or layer) is considered complete. If the cumulative dose does not match the target cumulative dose, additional treatment is performed. For example, the layer or configuration is scanned with the same configuration, again obtained from the table. The linear correlation between the magnet current and beam movement caused by the use of air-core magnets allows for repetition with the same configuration during multiple passes of the beam during scanning, and can facilitate relatively accurate and repeatable scanning. The leaves of the adaptive aperture described herein may move slightly (e.g., only a fraction of a millimeter, a millimeter, or a few millimeters) between each scan of the same region, as described above.

[0103] The scanning can be repeated in the same configuration for an appropriate number of times until the target cumulative dose is reached in each configuration. In this regard, depending on the target cumulative dose for different configurations on the layer, the entire layer may be rescanned, or only a selection of the layer may be rescanned. In some embodiments, the particle beam intensity does not change between scans. In other embodiments, the particle beam intensity may be changed between scans, especially if the dose that needs to be added to the cumulative dose in order to reach the target cumulative dose is small. The dose intensity can be increased or decreased, for example, by changing the operation of the ion source (e.g., increasing plasma ionization), changing the RF frequency sweep, or by other suitable methods.

[0104] As noted, scanning may be repeated for the entire layer or only a portion of the layer. In some embodiments, the entire layer or a portion thereof may be treated completely before another layer is treated. That is, scanning may be repeated until the total cumulative dose is reached for each placement on the layer before another layer is treated. In some embodiments, each layer may be treated partially in sequence (e.g., scanned only once) and then rescanned in sequence. In some embodiments, seven designated layers may be treated completely before the other layers are treated. In some embodiments, the entire target may be scanned once, and then continuous scanning of the entire target may be performed until an appropriate total cumulative dose is delivered to each placement.

[0105] During movement between layers, the beam may be turned off. For example, during movement between layers, the ion source may be turned off, thereby interrupting the beam output. During movement between layers, the RF sweep within the particle accelerator may be turned off, thereby interrupting the beam extraction (and therefore output). During movement between layers, the circuits that cause the ion source and RF sweep may both be stopped in some embodiments. In some embodiments, instead of turning off the ion source and / or RF sweep during movement between layers, the beam may be deflected to a beam-absorbing material using a kicker magnet (not shown) or scanning magnet.

[0106] Different cross-sections of the irradiation target may be scanned according to different treatment plans. As described above, an energy degrader is used to control the scanning depth. In some embodiments, the particle beam may be interrupted or reoriented when the energy degrader is configured. In other embodiments, this is not necessarily the case.

[0107] This specification describes examples of treating cross-sections of an irradiation target. These cross-sections may be approximately perpendicular to the direction of the particle beam. However, the concepts described herein are equally applicable to steps of treating other parts of an irradiation target that are not cross-sections perpendicular to the direction of the particle beam. For example, an irradiation target may be segmented into spherical, cubic, or other shaped volumetric sections, and these volumetric sections may be treated using the exemplary processes, systems, and / or devices described herein.

[0108] Figure 17 is a flowchart illustrating an exemplary embodiment of the scanning process described herein. Although process 200 in Figure 17 is described in the context of the hardware described herein, process 200 may be performed using any suitable hardware. The operations shown in process 200 may be performed in the same order as shown, or in a different order, where appropriate.

[0109] Process 200 stores the treatment plan (201). The treatment plan may be one of those described above. For example, the treatment plan may specify the type of scan (e.g., continuous raster scan) and the total cumulative dose of radiation to be delivered to each placement in each layer of the irradiation target. The treatment plan may omit, for example, the dose and intensity to be delivered for each scan in individual placements, as well as the number of doses to be delivered to each placement and the identification of the placement.

[0110] An energy degrader may be configured to select a layer (202), and a current may be applied to a magnet and controlled to move the particle beam according to a pattern described in, for example, a treatment plan, in order to scan the layer (203). Current control may cause a continuous movement of the beam over at least a portion of the irradiation target to deliver a dose of charged particles. An example of a beam movement 230 pattern on layer 233 of the irradiation target is shown in Figure 18. As the beam moves, each pulse of the beam delivers a dose of radiation to the target. The dose has an intensity that may be set in advance or during scanning in the accelerator and is delivered to a specific location. The exact location to which the dose should be delivered does not need to be set in advance, but rather may be reached by a combination of beam movement and pulse output.

[0111] Information identifying the location where the dose is delivered and the dose delivered to that location is stored (204) (or otherwise recorded in some form). This information is typically stored after the dose has been delivered. As described above, by using an ionization chamber to determine the intensity (e.g., dose) of the particle beam and using a current sensor on a scanning magnet to determine the location where the dose is delivered, information as close to the dose delivery as possible can be determined. As described above, in some embodiments, in synchronization with the delivery, information identifying the dose of the particle beam delivered to the irradiation target is stored along with at least one of the coordinates to which the dose was delivered or the magnetic current to which the dose was delivered. As also described above, this information may be stored in a table which can be used to store the cumulative dose of radiation applied to locations on various layers of the irradiation target.

[0112] As described above, the entire layer may be scanned and information recorded for it, or only a portion of the layer may be scanned and information recorded for it. The adaptive aperture is mounted on the appropriate placement of the scanning system so that the adaptive aperture can follow the movement of the particle beam during the scanning operation. At a point in time during scanning, the cumulative dose delivered at each position is compared to the target cumulative dose for that position. This may be done, for example, after a portion of the layer containing that position has been scanned, after the entire layer has been scanned, after a series of layers have been scanned, or after all layers in the irradiation target have been scanned. It is determined whether the current cumulative dose matches the target cumulative dose at a particular position (205). If the current cumulative dose matches the target cumulative dose at a particular position, the scanning is complete for those positions (207). If the current cumulative dose does not match the target cumulative dose at a particular position, the scanning system is made to compensate for the gap in the recorded dose (e.g., current cumulative) for the corresponding target cumulative dose at those positions. For example, if the current cumulative dose does not match the target cumulative dose at a particular location, the current in the scanning magnet may be controlled to move the beam (206) to deliver an additional dose to that location.

[0113] As described above, in some embodiments, 100% of the dose may be applied during a single scan of a layer (e.g., a single delivery of particles). In this case, multiple scans per layer may not be necessary. In other embodiments, less than 100% of the dose may be applied in a single scan. In this case, multiple scans per layer are necessary. To this end, according to the scanning process, for each location where the dose is applied, if the current cumulative dose at each location does not match the target cumulative dose at the corresponding location, the magnet current is controlled to move the beam to deliver an additional dose to the location where the dose is needed. In other words, a layer may be rescanned an appropriate number of times until the target cumulative dose is reached for all locations in the layer. In some embodiments, the actual dose delivered in one or more scans may exceed 100% of the target cumulative dose. The appropriate dose to be delivered may be instructed by a qualified medical professional.

[0114] As noted above, layers may be rescanned at appropriate times, for example, after a portion of a layer is completed in the current scan, after an entire layer is completed in the current scan, after a series of layers are completed in one scan, or after all layers are completed in one scan. During rescanning, the above process is repeated until the target cumulative dose is reached for all or a subset of the positions within the irradiation target. In some embodiments, the intensity of the particle beam may need to be adjusted, for example, for the last scan. For example, if the intensity is set to 25% of the target cumulative dose, but only 20% is delivered in each scan, a fifth (and possibly sixth) dose will require an intensity of less than 25% to reach the target cumulative dose.

[0115] The processes described herein are used with a single particle accelerator, and any two or more of these features described herein may be used with a single particle accelerator. Particle accelerators may be used for any type of medical or non-medical application. An example of a particle beam therapy system that can be used is presented below. In particular, the concepts described herein may be used in other systems not specifically described herein.

[0116] As shown in Figure 19, an exemplary embodiment of the charged particle beam therapy system 400 includes a beam-generating particle accelerator 402 (e.g., the particle accelerator in Figures 8 and 9), the weight and size of which are such that it can be mounted on a rotating gantry 404 when the output of the beam-generating particle accelerator 402 is directed linearly (i.e., substantially directly) from the accelerator housing toward the patient 406. The particle accelerator 402 also includes a scanning system of the type described herein (e.g., Figures 10 to 18).

[0117] In some embodiments, the steel gantry has two legs 408, 410, which are rotatably mounted to two bearings 412, 414 located on either side of the patient. The accelerator is supported by a steel truss 416 that is long enough to straddle the treatment area 418 on which the patient lies (for example, twice the height of the person, so that a tall person can be fully rotated in space while keeping the patient's desired target area on the beamline), and is stably mounted at both ends to the rotatable legs of the gantry.

[0118] In some embodiments, the rotation of the gantry 404 is limited to a range of less than 360° 420, for example, about 180°, which allows the floor 422 to extend from the walls of the vault 424 housing the treatment system into the interior of the patient treatment area. Furthermore, limiting the rotation range 420 of the gantry 404 allows for a reduction in the required thickness of some of the walls (those not directly aligned with the beam, e.g., wall 430) used to shield people outside the patient treatment area from radiation. While a rotation range 420 of 180° is sufficient to accommodate all treatment approach angles, expanding the range of movement is advantageous. For example, a rotation range 420 of 180° to 330° can still ensure sufficient clearance for the floor area for treatment. In other embodiments, the rotation is not limited as described above.

[0119] The horizontal rotation axis 432 of the gantry 404 is positioned nominally 1 meter above the floor where the patient and therapist interactively operate the treatment system. This floor is positioned approximately 3 meters above the lowest floor of the shielding vault 424 of the charged particle beam therapy system 400. The beam-generating particle accelerator 402 is rotatable below the elevated floor to irradiate the treatment beam from below the rotation axis. The patient couch moves and rotates in a horizontal plane that is substantially parallel to the rotation axis 432 of the gantry 404. The couch is rotatable over a range of approximately 270° 434 in the horizontal plane by this configuration. The combination of the rotation ranges 420, 434 and degrees of freedom of the gantry 404 and the patient allows the therapist to substantially select any approach angle for the beam. If necessary, all conceivable angles become available by positioning the patient in the couch in the opposite direction.

[0120] In some embodiments, the beam-generating particle accelerator 402 utilizes a synchrocyclotron having a high-field superconducting electromagnetic structure. Since the radius of curvature of a charged particle with a predetermined kinetic energy decreases in direct proportion to the increase in the magnetic field applied to the charged particle, the accelerator can be made smaller and lighter by utilizing a high-field superconducting magnetic structure. A synchrocyclotron utilizes a magnetic field with a uniform rotation angle, where the intensity decreases as the radius increases. Since such a magnetic field shape can be realized regardless of the magnitude of the magnetic field, there is theoretically no upper limit on the magnetic field intensity (and consequently, the resulting particle energy at a fixed radius) that can be used within the synchrocyclotron.

[0121] The synchrocyclotron is supported by a gantry so that the beam is generated directly onto the patient. The gantry can rotate the synchrocyclotron around a horizontal axis of rotation that includes a point inside or near the patient (isocenter 440). A split truss, parallel to the horizontal axis of rotation, supports the synchrocyclotron on both sides.

[0122] In some exemplary embodiments, the range of rotation of the gantry is limited so that the patient support area can be contained within a wide area around an isocenter. Since the floor can extend over a wide area around the isocenter, the patient support platform is positioned to move relative to a vertical axis 442 passing through the isocenter and to rotate about the vertical axis 442, and the combination of the rotation of the gantry and the movement and rotation of the patient support platform allows the beam to be directed at any angle toward any part of the patient. In some embodiments, the two gantry arms are spaced apart by a length greater than twice the height of a tall patient so that the couch with the patient on it can be rotated and translated in a horizontal plane located above the elevated floor.

[0123] By limiting the rotation angle of the gantry, the thickness of at least one of the walls surrounding the treatment room can be reduced. Generally, thick concrete walls protect people outside the treatment room from radiation. The downstream wall, which blocks the proton beam, may be about twice as thick as the wall on the opposite side of the treatment room to achieve a similar level of protection. Limiting the rotation of the gantry allows the treatment room to be set below earth grade on three sides, while the occupied area can be adjacent to the thinnest wall, thus reducing the cost of constructing the treatment room.

[0124] In the exemplary embodiment shown in Figure 19, the superconducting synchrocyclotron 402 operates with a peak magnetic field of 8.8 Tesla in the synchrocyclotron's pole gap. The synchrocyclotron generates a proton beam with an energy of 250 MeV. In some embodiments, the synchrocyclotron is a variable-energy machine and can output proton beams of different energies. In some embodiments, the synchrocyclotron can generate a beam with a fixed energy. In some embodiments, the field intensity can be in the range of 4 T to 20 T, and the proton energy can be in the range of 100 to 300 MeV.

[0125] The radiation therapy system described in this example is used for proton radiation therapy, but the same principles and details can be applied to similar systems for use in heavy ion (ion) therapy systems.

[0126] As shown in Figures 8, 9, 20, 21, and 22, an exemplary synchrocyclotron 10 (e.g., 402 in Figure 19) includes a magnet system 122 housing a particle source 190, a high-frequency drive system 191, and a beam extraction system. In this example, the magnetic field established by the magnet system has a shape suitable for maintaining focus of the proton beam present inside, using a combination of a divided pair of annular superconducting coils 140, 142 and a pair of shaped ferromagnetic (e.g., low-carbon steel) pole surfaces 144, 146.

[0127] Two superconducting magnetic coils are arranged in phases along a common axis. The coils can be formed from 0.8 mm diameter Nb3Sn superconducting wire (initially featuring a niobium-tin core surrounded by a copper sheath) arranged in the form of twisted cable-in-channel conductors. After seven individual wires are bundled together to form a cable, they are heated to trigger a reaction that forms a wire-like final (brittle) superconductor. After the material has reacted, the wire is soldered into a copper channel (outer diameter 3.18 × 2.54 mm and inner diameter 2.08 × 2.08 mm) and covered with an insulator (in this example, a glass fiber woven cloth). The wire is then wound into a copper channel coil that houses the wire, which has a rectangular cross-section. This wound coil is then vacuum-impregnated with an epoxy compound. The completed coil is mounted on an annular stainless steel reverse bobbin. Heater blankets are placed at intervals within the winding layers to protect the assembly in case of magnetic quenching.

[0128] Next, the entire coil is covered with copper plates to provide thermal conductivity and mechanical stability, and then housed in an additional epoxy layer. Pre-compression of the coil can be performed by heating a stainless steel reverse bobbin and fitting the coil into the reverse bobbin. The inner diameter of the reverse bobbin is selected so that when the entire mass cools to 4K, the reverse bobbin remains in contact with the coil, resulting in some compression. This can be achieved by heating the stainless steel reverse bobbin to about 50°C and fitting the coil at a Kelvin temperature of 100°C.

[0129] The coil's geometric shape is maintained by mounting the coil in a rectangular "reverse" bobbin, which provides a restoring force that acts against the strain-causing forces generated when the coil is energized. As shown in Figure 21, in some embodiments, the coil position is maintained relative to the corresponding pole piece and cryogenic retainer using a set of high-temperature-low-temperature support straps 402, 404, and 406. By supporting the cryogenic mass with thin straps, heat leakage to the cryogenic mass by the rigid support system is reduced. The straps are configured to withstand the changing gravitational forces acting on the coil as the gantry rotates with the magnets mounted. They withstand the combined effect of gravity and the large eccentric force generated by the coil when it perturbs from a perfectly symmetrical position with respect to the magnetic yoke. In addition, the links help to reduce the dynamic forces exerted on the coil as the gantry accelerates and decelerates when the position changes. Each high-temperature-low-temperature support may include one S2 glass fiber link and one carbon fiber link. The carbon fiber links are supported on pins between the high-temperature yoke and the intermediate temperature (50-70K), while the S2 glass fiber links 408 are supported on pins attached to the intermediate temperature pins and the low-temperature mass. Each pin can be made from high-tensile stainless steel.

[0130] Referring to Figure 8, the field intensity profile as a function of radius is largely determined by the choice of coil geometry and pole surface shape. The pole surfaces 144, 146 of the permeable yoke material can be undulated to fine-tune the shape of the magnetic field and ensure the focusing of the particle beam during acceleration.

[0131] The superconducting coil is maintained at a temperature near absolute zero (e.g., about 4 Kelvin) by enclosing the coil assembly (coil and bobbin) inside a vacuumed annular aluminum or stainless steel cryogenic holding chamber 170 (cryogenic holding device) that provides free space around the coil structure, except for a limited set of support points 171, 173. In an alternative version (e.g., Figure 9), the outer wall of the cryogenic holding device may be made of low-carbon steel, providing an additional magnetic feedback path to the magnetic field.

[0132] In some embodiments, temperatures near absolute zero are achieved and maintained using one single-stage Gifford-McMahon refrigerator and three two-stage Gifford-McMahon refrigerators. Each two-stage refrigerator has a second-stage low-temperature end attached to a condenser that recondenses helium vapor into liquid helium. In some embodiments, temperatures near absolute zero are achieved and maintained using a cooling channel (not shown) containing liquid helium, which is formed inside a superconducting coil support structure (e.g., a reverse bobbin) and includes a thermal connection between the liquid helium in the channel and the corresponding superconducting coil.

[0133] In some embodiments, the coil assembly and cryogenic holding chamber are housed within two halves 181, 183 of a pillbox-shaped magnet yoke 100, thereby completely enclosed. The yoke 100 serves as a path for the return flux 184, magnetically shielding the volume 186 between the pole surfaces 144, 146 to prevent external magnetic influences from perturbing the shape of the magnetic field within that volume. The yoke also serves to reduce the stray magnetic field near the accelerator. In other embodiments, the coil assembly and cryogenic holding chamber are housed within a non-magnetic enclosure, thereby completely enclosed, and the return flux is implemented using an active feedback system, one example of which is described above.

[0134] As shown in Figures 8 and 23, the synchrocyclotron includes a particle source 190 in the form of a Penning ion gauge, located near the geometric center 192 of the magnetic structure. The particle source may be as described below.

[0135] The particle source 190 is supplied from a hydrogen supply unit 399 through a gas pipeline 393 and a pipe 394 that delivers gaseous hydrogen. An electrical cable 294 carries an electric current from a current source, stimulating the emission of electrons from cathodes 392 and 390 aligned in the direction of the magnetic field.

[0136] In this example, the emitted electrons ionize the gas coming out of tube 394 through a small hole, forming a supply of positive ions (protons) accelerated by a single semicircular (D-shaped) high-frequency plate that spans half of the space enclosed by the magnetic structure and one dummy D-plate. In the case of a blocked particle source, all (or substantial portion, e.g., most) of the tube containing the plasma is removed in the acceleration region.

[0137] As shown in Figure 24, the deep plate 500 is a hollow metal structure having two semicircular surfaces 503, 505 that surround the space 507 in which protons are accelerated, at half the rotation around the space enclosed by the magnetic structure. A duct 509 that opens into space 507 extends through an enclosure (e.g., a yoke or pole piece) to an external location where a vacuum pump may be installed, thereby creating a vacuum in space 507 and the rest of the space in the vacuum chamber in which the acceleration takes place. A dummy dee 502 comprises rectangular metal rings spaced apart near the exposed edge of the deep plate. The dummy dee is grounded to the vacuum chamber and the magnetic yoke. The deep plate 500 is driven by a high-frequency signal applied to the termination of a high-frequency transmission line, generating an electric field in space 507. The high-frequency electric field is varied with respect to time as the accelerated particle beam increases its distance from the geometric center.

[0138] As the beam emerges from the centrally located particle source, clears the particle source structure, and begins to spiral outward, a high voltage difference can be applied to the high-frequency plate. 20,000V is applied to the high-frequency plate. In some versions, 8,000 to 20,000 volts can be applied to the high-frequency plate. To reduce the power required to drive this high voltage, the magnet structure is configured to reduce the capacitance between the high-frequency plate and ground. This can be done by forming holes with sufficient spacing between the high-frequency structure and the outer yoke and cryogenic holding device housing, thereby ensuring sufficient space between the magnetic pole surfaces.

[0139] The high-voltage AC potential driving the D-plate is swept to a lower frequency during the acceleration cycle, taking into account the increasing relativistic mass of the protons and the decreasing magnetic field. Since the D-plate is at ground potential with the vacuum chamber wall, it does not require a hollow semi-cylindrical structure. Other plate configurations are also possible, such as multiple pairs of accelerating electrodes driven at different phases or multiples of the fundamental frequency. The RF structure can be tuned to maintain a high Q at the required frequency sweep, for example, by using a rotating capacitor with interlocking rotating and stationary blades. With each blade engagement, the capacitance increases, and therefore the resonant frequency of the RF structure decreases. The blades can be shaped to produce the precise frequency sweep required. The drive motor for the rotating capacitor can be phase-fixed to the RF generator for precise control. A group of particles can be accelerated with each engagement of the rotating capacitor blades.

[0140] The vacuum chamber in which acceleration takes place is typically a cylindrical container, thinner in the center and thicker at the edges. The vacuum chamber contains the RF plate and particle source and is evacuated by a vacuum pump. Maintaining a high vacuum reduces the probability of accelerated ions being lost in collisions with gas molecules, making it possible to maintain a higher RF voltage level without causing arc ground faults.

[0141] Protons (or other ions) traverse a generally helical orbital path starting from the particle source. In each half of the loop of the helical path, the proton gains energy as it passes through the RF electric field. As the proton gains energy, the radius of the central orbit of each successive loop of the helical path becomes larger than the previous loop until the loop radius reaches the maximum radius of the magnetic pole surface. At that point, magnetic and electric field perturbations guide the proton into a region where the magnetic field rapidly decreases, and the proton exits the high-magnetic-field region, passing through a vacuum tube referred to herein as the extraction channel and exiting the synchrocyclotron. Magnetic regenerators may be used to change the magnetic field perturbation and determine the orientation of the proton. The exiting proton tends to disperse as it enters a region of significantly decreasing magnetic field present in the chambers surrounding the synchrocyclotron. Beam shaping elements 507, 509 in the extraction channel 138 (Figure 21) reorient the proton so that it maintains a straight beam state with limited spatial spread.

[0142] As the beam exits the extraction channel, it passes through a beamforming system 525 (Figure 21), which may include a scanning system of the type described herein. The beamforming system 525 may be used in conjunction with an inner gantry that controls the beam application.

[0143] The stray magnetic field emanating from the synchrocyclotron can be limited by both the magnetic yoke (which also acts as a shield) and another magnetic shield 514 (e.g., Figure 8). The other magnetic shield includes a layer 517 of ferromagnetic material (e.g., steel or iron) surrounding the pillbox yoke, separated by a space 516. This configuration, including the sandwich of yoke, space, and shield, forms adequate shielding against a given stray magnetic field at a lower weight. As described above, in some embodiments, an active feedback system may be used to replace or enhance the operation of the magnetic yoke and shield.

[0144] As shown in Figure 19, the gantry rotates the synchrocyclotron around a horizontal axis of rotation 432. The truss structure 416 has two substantially parallel spans 480 and 482. The synchrocyclotron is positioned approximately in the center between the legs and between spans 580 and 582. The gantry is balanced to rotate around a bearing by utilizing counterweights 622 and 624 attached to the ends of the legs located on the opposite side of the truss.

[0145] The gantry 404 is rotationally driven by an electric motor, which is mounted on at least one leg of the gantry 404 and connected to a bearing housing via a drive gear. The rotational position of the gantry 404 is derived from signals provided by shaft angle encoders incorporated into the drive motor and drive gear of the gantry 404.

[0146] At the point where the ion beam exits the synchrocyclotron, the beamforming system 525 acts on the ion beam to impart properties suitable for patient treatment. For example, by diffusing the beam and changing the beam penetration depth, it can be uniformly radiated to a given target volume. The beamforming system may include active scanning elements as described herein.

[0147] All of the active systems of the synchrocyclotron (e.g., current-driven superconducting coils, RF-driven plates, vacuum pumps for the vacuum acceleration chamber and superconducting coil cooling chamber, current-driven particle sources, hydrogen gas sources, and RF plate cooling devices) can be controlled by appropriate synchrocyclotron control electronics (not shown), which may include one or more processing devices that execute and control instructions from, for example, non-temporary memory.

[0148] As described above, as shown in system 602 of Figure 25, the beam-generating particle accelerator, in this case a synchrocyclotron 604 (which may include any and all of the features described herein), can be mounted on a rotating gantry 605. The rotating gantry 605 is of the type described herein and can rotate angularly around the patient support 606. This feature allows the synchrocyclotron 604 to irradiate the patient with the particle beam essentially directly from various angles. For example, as shown in Figure 25, when the synchrocyclotron 604 is positioned above the patient support 606, the particle beam is directed downward toward the patient. Alternatively, when the synchrocyclotron 604 is positioned below the patient support 606, the particle beam is directed upward toward the patient. The particle beam is applied essentially directly to the patient in the sense that an intermediate beam pathing mechanism is not required. In this invention, the intermediate beam path designation mechanism differs from the shaping or sizing mechanism in that, rather than changing the beam path, it determines the size and / or shape of the beam while maintaining the same and general beam trajectory.

[0149] The particle accelerators used in the exemplary particle beam therapy systems and exemplary scanning systems described herein may be variable energy particle accelerators, one example of which is described below.

[0150] 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 reduced after extraction and before treatment based on the need for treatment. As shown in Figure 26, an exemplary treatment system 910 includes an accelerator 912, e.g., a synchrocyclotron, from which a variable-energy particle (e.g., proton) beam 914 is extracted and irradiated onto a target volume section 924 of a body 922. Optionally, one or more additional devices, such as a scanning unit 916 or scattering unit 916, one or more monitoring units 918, and an energy degrader 920, are placed along the irradiation direction 928. These devices block the cross-section of the extracted beam 914 and alter the properties of one or more extracted beams for treatment.

[0151] The target volume (irradiation target) to which a particle beam is irradiated for treatment typically has a three-dimensional configuration. In some examples, to perform treatment, the target volume is divided into several layers along the direction of particle beam irradiation so that irradiation occurs layer by layer. For some types of particles, such as protons, the penetration depth (or layer to which the beam reaches) within the target volume is determined solely by the energy of the particle beam. A particle beam of a given energy will not substantially exceed the corresponding penetration depth for that energy. The energy of the particle beam is changed to move the beam irradiation from one layer to the other within the target volume.

[0152] In the example shown in Figure 26, the target volume 924 is divided into nine layers 926a to 926i along the irradiation direction 928. In the exemplary process, irradiation begins with the deepest layer 926i and progresses gradually to shallower layers, one layer at a time, ending at the shallowest layer 926a. Before being applied to the body 922, the energy of the particle beam 914 is controlled to a level at which the particle beam can stop at a desired layer, e.g., layer 926d, without substantially penetrating further into the body or the target volume, e.g., layers 926e to 926i, or deeper into the body. In some examples, the desired energy of the particle beam 914 decreases as the treatment layer becomes shallower with respect to 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, but other differences are also possible, e.g., depending on the layer thickness and beam characteristics.

[0153] Energy changes for treating different layers of the target volume section 924 can, in some embodiments, be performed in the accelerator 912 so that no additional energy changes are required after the particle beam is extracted from the accelerator 912 (e.g., the energy can be changed on the accelerator side). Thus, an optional energy degrader 920 in the treatment system 10 can be eliminated from the system. In some embodiments, the accelerator 912 can output a particle beam with an energy that varies between about 100 MeV and about 300 MeV, for example between about 115 MeV and about 250 MeV. The changes may be continuous or discontinuous, for example, one step at a time. In some embodiments, continuous or discontinuous changes may occur at relatively high rates, for example, up to about 50 MeV per second or up to about 20 MeV per second. Discontinuous changes may be performed one step at a time with a step size of about 10 MeV to about 90 MeV.

[0154] Once irradiation of one layer is complete, the accelerator 912 can change the energy of the particle beam to irradiate the next layer, for example, within a few seconds or less than a second. In some embodiments, treatment of the target volume section 924 can be continued with virtually no interruption or with any interruption whatsoever. In some situations, the step size of the discontinuous energy change is selected to correspond to the energy difference required to irradiate two adjacent layers of the target volume section 924. For example, the step size may be the same as the energy difference or a fraction thereof.

[0155] In some embodiments, the accelerator 912 and degrader 920 work together to change the energy of the beam 914. For example, coarse adjustment is performed in the accelerator 912 and fine adjustment in the degrader 920, or vice versa. In this example, the accelerator 912 can output a particle beam whose energy is changed in change steps of about 10 to 80 MeV, and the degrader 920 adjusts (e.g., reduces) the beam's energy in change steps of about 2 to 10 MeV.

[0156] Reducing (or eliminating) the use of energy degraders, such as range modulators, can make it easier to maintain the characteristics and quality of the output beam from the accelerator, such as beam intensity. Particle beam control can be performed at the accelerator. Side effects, such as those from neutrons generated when the particle beam passes through degrader 920, can be reduced or eliminated.

[0157] The energy of the particle beam 914 may be adjusted to treat another target volume 930 in a different body or body part 922' after treatment is complete in the target volume 924. The target volumes 924, 930 may be in the same body (or patient) or in different patients. The depth D of the target volume 930 from the surface of body 922' may differ from the depth of the pallet volume 924. Some energy adjustment may be performed by the degrader 920, but the degrader 912 can only reduce the beam energy and cannot increase it.

[0158] In this regard, in some cases, the beam energy required to treat the target volume section 930 is greater than the beam energy required to treat the target volume section 924. In such cases, the accelerator 912 can increase the output beam energy after treating the target volume section 924 and before treating the target volume section 930. In other cases, the beam energy required to treat the target volume section 930 is less than the beam energy required to treat the target volume section 924. Although the degrader 920 can reduce the energy, the accelerator 912 can be adjusted to output a lower beam energy to reduce or eliminate the use of the degrader 920. The division of the target volume sections 924 and 930 into several layers may be different or the same. The target volume section 930 can be treated in a similar manner to the treatment of the target volume section 924, layer by layer.

[0159] Treatment of different target volume units 924 and 930 of the same patient is substantially continuous, for example, the downtime between the two volume units may not be longer than approximately 30 minutes, e.g., 25 minutes, 20 minutes, 15 minutes, 10 minutes, 5 minutes, or 1 minute. As described herein, the accelerator 912 can be mounted on a movable gantry, and the movement of the gantry allows the accelerator to be moved towards different target volume units. In some situations, the accelerator 912 can complete energy adjustment of the output beam 914 while adjustments (such as moving the gantry) are being made after the treatment system has completed treatment of target volume unit 924 and before starting treatment of target volume unit 930. After alignment of the accelerator with the target volume unit 930, treatment can be started with the adjusted desired beam energy. Beam energy adjustment for different patients can also be completed relatively efficiently. In some cases, all adjustments, including steps to increase / decrease beam energy and / or move the gantry, are performed within approximately 30 minutes, for example, within approximately 25 minutes, 20 minutes, 15 minutes, 10 minutes, or 5 minutes.

[0160] In the same layer of the volumetric section, the irradiation dose can be applied by using a scanning unit 916 to move the beam from one end of the layer's two-dimensional surface to the other (also referred to as a scanning beam). Alternatively, the layer may be irradiated by passing a beam (also referred to as a scattered beam) extracted from one or more scatterers of a scattering unit 16.

[0161] Beam characteristics such as energy and intensity may be selected before treatment or adjusted during treatment by controlling the accelerator 912 and / or other devices such as the scanning unit / scatterer 916, the degrader 920, and others not shown. In exemplary embodiments, the system 910 includes a control device 932, such as a computer, which communicates with one or more devices in the system. The control may be based on the results of monitoring performed by one or more monitors 918, e.g., beam intensity, dose, beam placement within the target volume. The monitors 918 are shown as being located between device 916 and the degrader 920, but one or more monitors may be placed in other appropriate locations along the beam irradiation path. The control device 932 may also store treatment plans for one or more target volume (for the same patient and / or different patients). The treatment plan is determined before treatment begins and may include parameters such as the shape of the target volume, the number of irradiation layers, the irradiation dose for each layer, and the number of times each layer is irradiated. Adjustment of beam characteristics within the system 910 may be performed based on the treatment plan. Additional adjustments may be made during treatment, for example, when a deviation from the treatment plan is detected.

[0162] In some embodiments, the accelerator 912 is configured to vary the energy of the output particle beam by changing the magnetic field through which the particle beam is accelerated. In one exemplary embodiment, one or more sets of coils receive a fluctuating current to generate a fluctuating magnetic field within the cavity. In some examples, one set of coils receives a fixed current, while one or more other sets of coils receive a fluctuating current such that the total current received by the coil set changes. In some embodiments, all sets of coils are superconducting. In other embodiments, some sets of coils, such as the set for the fixed current, are superconducting, while other sets, such as one or more sets for the fluctuating current, are not superconducting. In some examples, all sets of coils are not superconducting.

[0163] Generally, the magnitude of a magnetic field can be increased or decreased at a constant rate with the magnitude of the current. By adjusting the total current in a coil to a predetermined range, a magnetic field that varies within that range can be generated. In some examples, continuous adjustment of the current can cause continuous fluctuations in the magnetic field and continuous fluctuations in the output beam energy. Alternatively, if the current applied to the coil is adjusted in a discontinuous, stepwise manner, the magnetic field and output beam energy will also change in a discontinuous (stepwise) manner accordingly. While the beam energy can be changed relatively precisely by increasing or decreasing the magnetic field at a constant rate according to the current, sometimes fine adjustments other than the input current can be made.

[0164] In some embodiments, to output a particle beam with variable energy, the accelerator 912 is configured to apply an RF voltage that sweeps across different frequency ranges, each corresponding to a different output beam energy. For example, if the accelerator 912 is configured to generate three different output beam energies, the RF voltage can be swept across three different frequency ranges. In another example, to accommodate a continuous beam energy change, the RF voltage sweeps across a continuously changing frequency range. The different frequency ranges may have different lower and / or upper frequency boundaries.

[0165] Extraction channels can be configured to adapt to different energy ranges produced by a variable-energy particle accelerator. For example, the extraction channel may be large enough to support the highest and lowest energies produced by the particle accelerator. That is, the extraction channel may be sized to receive and transmit particles within that energy range, or may be configured in some other way. Particle beams with different energies can be extracted from accelerator 912 without altering the characteristics of the regenerator used to extract a particle beam with a single energy. In other embodiments, to adapt to variable particle energies, the regenerator can be moved to disturb (e.g., change) different particle trajectories in the manner described above, and / or iron rods (magnetic shims) can be added or removed to alter the magnetic field bumps produced by the regenerator. More specifically, different particle energies typically result in different particle trajectories within a cavity. By moving the regenerator, it is possible to intercept a particle trajectory at a specified energy, thereby causing the correct perturbation of that trajectory so that particles at the specified energy reach the extraction channel. In some embodiments, the regenerator movement (and / or the addition / removal of magnetic shims) is performed in real time to match the real-time changes in the particle beam energy output by the accelerator. In other embodiments, the particle energy is adjusted for each treatment, and the regenerator movement (and / or the addition / removal of magnetic shims) is performed before the treatment. In any case, the regenerator movement (and / or the addition / removal of magnetic shims) may be computer-controlled. For example, a computer may control one or more motors that cause the regenerator and / or magnetic shim movement.

[0166] In some embodiments, the regenerator is implemented using one or more magnetic shims that can be controlled to move to the appropriate position.

[0167] For example, Table 1 shows three exemplary energy levels from which an exemplary accelerator 912 can output a particle beam. The corresponding parameters for generating the three energy levels are also listed. In this context, the magnet current refers to the total current applied to one or more sets of coils within accelerator 912, the highest and lowest frequencies define the range over which the RF voltage sweeps, and "r" is the radial distance from the location to the center of the cavity from which the particle is accelerated.

[0168] [Table 1]

[0169] Details that may be included in an exemplary particle accelerator that generates charged particles with variable energy are described below. The accelerator may be a synchrocyclotron, 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 can be varied while treating one target volume in the patient's body, or between treatments of different target volumes in the same or different patients. In some embodiments, the accelerator settings are modified to vary the beam energy when no beam (or particles) are being output from the accelerator. The energy variation may be continuous or discontinuous over a desired range.

[0170] As illustrated in the example shown in Figure 8, a particle accelerator, which may be a variable-energy particle accelerator such as particle accelerator 912 described above, can be configured to output a particle beam with variable energy. The variable energy range may have an upper boundary of about 200 MeV to about 300 MeV or more, for example, 200 MeV, about 205 MeV, about 210 MeV, about 215 MeV, about 220 MeV, about 225 MeV, about 230 MeV, about 235 MeV, about 240 MeV, about 245 MeV, about 250 MeV, about 255 MeV, about 260 MeV, about 265 MeV, about 270 MeV, about 275 MeV, about 280 MeV, about 285 MeV, about 290 MeV, about 295 MeV, or about 300 MeV or more. This range can also have a lower bound, for example, from approximately 100 MeV or less to approximately 200 MeV, such as approximately 100 MeV or less, approximately 105 MeV, approximately 110 MeV, approximately 115 MeV, approximately 120 MeV, approximately 125 MeV, approximately 130 MeV, approximately 135 MeV, approximately 140 MeV, approximately 145 MeV, approximately 150 MeV, approximately 155 MeV, approximately 160 MeV, approximately 165 MeV, approximately 170 MeV, approximately 175 MeV, approximately 180 MeV, approximately 185 MeV, approximately 190 MeV, approximately 195 MeV, and approximately 200 MeV.

[0171] In some cases, this change is discontinuous, and the change steps can be of sizes of approximately 10 MeV or less, 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 more. The time required to change the energy by one step size may be within 30 minutes, for example, within approximately 25 minutes, within approximately 20 minutes, within approximately 15 minutes, within approximately 10 minutes, within approximately 5 minutes, within approximately 1 minute, or within approximately 30 seconds. In other examples, this change is continuous, and the accelerator can adjust the particle beam energy at relatively high rates, for example, up to approximately 50 MeV / s, up to approximately 45 MeV / s, up to approximately 40 MeV / s, up to approximately 35 MeV / s, up to approximately 30 MeV / s, up to approximately 25 MeV / s, up to approximately 20 MeV / s, up to approximately 15 MeV / s, or up to approximately 10 MeV / s. The accelerator can be configured to adjust the particle energy continuously or discontinuously. For example, a combination of continuous and discontinuous changes can be used to treat one target volume or different target volumes. Flexible treatment planning and flexible treatment can be achieved.

[0172] Particle accelerators that output particle beams with variable energy can enable more precise irradiation therapy and reduce the number of additional devices (other than the accelerator) used in treatment. For example, the use of degraders to change the energy of the output particle beam can be reduced or eliminated for all or part of the treatment. Particle beam properties such as intensity and focus are controlled on the particle accelerator side, and the particle beam can reach the target volume without substantial interference from additional devices. The relatively high rate of change of beam energy can shorten treatment time and enable efficient use of the treatment system.

[0173] In some embodiments, accelerators such as the synchrocyclotron in Figure 8 accelerate particles or particle beams to variable energy levels by changing the magnetic field within the accelerator, which can be achieved by changing the current applied to coils to generate the magnetic field. As described above, an exemplary synchrocyclotron (e.g., the synchrocyclotron in Figure 8) comprises a magnet system housing a particle source, a radio frequency drive system, and a beam extraction system. Figure 27 shows an example of a magnet system that may be used in a variable energy accelerator. In this exemplary embodiment, the magnetic field established by the magnet system 1012 can vary from about 5% to about 35% of the maximum magnetic field that two coil sets 40a and 40b, and 42a and 42b, can generate. The magnetic field established by the magnet system has a shape suitable for maintaining focus of a proton beam housed using a combination of two coil sets and a pair of shaped ferromagnetic (e.g., low-carbon steel) structures, an example of which is presented above.

[0174] Each coil set may be a divided pair of annular coils for receiving current. In some situations, both coil sets are superconducting. In other situations, only one coil set is superconducting, and the other set is non-superconducting or normal conducting (as further described below). It is also possible for both coil sets to be non-superconducting. Suitable superconductors for use in coils include niobium-tin (Nb3Sn) and / or niobium-titanium. Other normal conductors may include copper. Examples of coil set construction are further described below.

[0175] Two coil sets can be electrically connected in series or parallel. In some embodiments, the total current received by the two coil sets may range from about 2 million ampere-times to about 10 million ampere-times, for example, from about 2.5 million to about 7.5 million ampere-times, or from about 3.75 million to about 5 million ampere-times. In some examples, one coil set is configured to receive a fixed (or constant) portion of the total variable current, and the other coil set is configured to receive a variable portion of the total current. The total current of the two coil sets changes with the change in current in one coil set. In other situations, the current applied to both coil sets may change. The variable total current in the two coil sets can generate a magnetic field of varying magnitude, which then changes the acceleration path of particles, generating particles with variable energy.

[0176] Generally, the magnitude of the magnetic field generated by a coil can be increased or decreased by a constant ratio depending on the magnitude of the total current applied to the coil. Based on this constant ratio of increase or decrease, in some embodiments, a linear change in magnetic field strength can be achieved by linearly changing the total current of the coil set. The total current can be adjusted relatively quickly, thereby adjusting the magnetic field and beam energy relatively quickly.

[0177] In the examples reflected in Table 1 above, the ratio of the current value to the magnetic field value at the geometric center of the coil ring is 1990:8.7 (approximately 228.7:1), 1920:8.4 (approximately 228.6:1), and 1760:7.9 (approximately 222.8:1). Therefore, by adjusting the magnitude of the total current applied to the superconducting coil, the magnitude of the magnetic field can be proportionally adjusted (based on the ratio).

[0178] The constant ratio of the magnetic field to the total current in the example in Table 1 is also shown in the plot in Figure 28, where BZ is the magnetic field along the Z direction and R is the radial distance measured from the geometric center of the coil ring along the direction perpendicular to the Z direction. The magnetic field has its highest value at the geometric center and decreases as the distance R increases. Curves 1035 and 1037 represent the magnetic fields generated by the same coil set receiving different total currents of 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 the different portions of curves 1035 and 1037 are substantially parallel. As a result, either curve 1035 or curve 1037 may be linearly shifted to substantially coincide with the other curve, indicating that the magnetic field can increase or decrease at a constant ratio depending on the total current applied to the corset.

[0179] In some embodiments, the constant ratio increase or decrease 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. Also, as shown in Figure 28, linearly shifting one curve may not result in a perfect match with the other curve. In some embodiments, the total current is applied to the coil set under the assumption that the constant ratio increase or decrease is perfect. The target magnetic field (under the assumption that the constant ratio increase or decrease is perfect) can be generated by, in addition, changing the coil features, e.g., the geometric shape, to compensate for the imperfections of the constant ratio increase or decrease. In one example, a rod (magnetic shim) of ferromagnetic material (e.g., iron) can be inserted into or removed from one or both sides of the magnetic structure (e.g., yoke, pole piece, etc.). The coil features can be changed relatively quickly so that the speed of magnetic field adjustment is not substantially affected compared to a situation where the constant ratio increase or decrease is perfect and only the current needs to be adjusted. In the example of an iron rod, the rod can be added or removed in time units of seconds or minutes, for example, within 5 minutes, within 1 minute, less than 30 seconds, or less than 1 second.

[0180] In some embodiments, accelerator settings, such as the current applied to the coil set, can be selected based on a substantial increase or decrease in a constant ratio of the magnetic field to the total current in the coil set.

[0181] In general, an appropriate combination of currents applied to two coil sets can be used to generate a total current that varies within a desired range. In one example, coil sets 42a and 42b may be configured to receive a fixed total current corresponding to the lower boundary of the desired range of the magnetic field. In the example shown in Table 1, the fixed current is 1760 amperes. In addition, coil sets 40a and 40b may be configured to receive a variable current with an upper boundary corresponding to the difference between the upper and lower boundaries of the desired range of the magnetic field. In the example shown in Table 1, coil sets 40a and 40b are configured to receive a current that varies between 0 amperes and 230 amperes.

[0182] In another example, coil sets 42a and 42b may be configured to receive a fixed current corresponding to the upper boundary of a desired range of magnetic fields. In the example shown in Table 1, the fixed current is 1990 amperes. In addition, coil sets 40a and 40b may be configured to receive a variable current with an upper boundary corresponding to the difference between the lower and upper boundaries of a desired range of magnetic fields. In the example shown in Table 1, coil sets 40a and 40b are configured to receive a current that varies between -230 amperes and 0 amperes.

[0183] The total variable magnetic field generated by the variable total current for accelerating the particles may 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, up to about 20 Tesla, for example up to about 18 Tesla, up to about 15 Tesla, or up to about 12 Tesla. In some embodiments, the change in the total current in the coil set can change the magnetic field from about 0.2 Tesla to about 4.2 Tesla or more, for example from about 0.2 Tesla to about 1.4 Tesla or from about 0.6 Tesla to about 4.2 Tesla. In some situations, the amount of change in the magnetic field may be proportional to the maximum magnitude.

[0184] Figure 29 shows an exemplary RF structure for sweeping a voltage over a constant RF frequency range for each energy level of a particle beam and changing the frequency range as the particle beam energy changes. The semicircular surfaces 503, 505 of the deep plate 500 are connected to an internal conductor 1300 and housed within an external conductor 1302. A high voltage is applied to the deep plate 500 from a power source (not shown, e.g., an oscillating voltage input) through a power coupling device 1304 that couples the power source to the internal conductor. In some embodiments, the coupling device 1304 is located on the internal conductor 1300 and transmits power from the power source to the deep plate 500. In addition, the deep plate 500 is coupled to variable reactance elements 1306, 1308 that perform RF frequency sweeps for each particle energy level and change the RF frequency range for different particle energy levels.

[0185] The variable reactance element 1306 may be a rotating capacitor having a plurality of blades 1310 that are rotatable by a motor (not shown). By engaging or disengaging the blades 1310 in each cycle of the RF sweep, the capacitance of the RF structure changes, and therefore the resonant frequency of the RF structure changes. In some embodiments, the blades 1310 engage with each other every quarter cycle of the motor. The capacitance of the RF structure increases, and the resonant frequency decreases. This process is reversed when the blades 1310 disengage. As a result, the power required to generate the high voltage applied to the deep plate 103 and to accelerate the beam can be significantly reduced. In some embodiments, the shape of the blades 1310 is machined to produce the desired dependence of the resonant frequency on time.

[0186] The generation of the RF frequency is synchronized with the blade rotation by sensing the phase of the RF voltage within the resonator and maintaining an AC voltage on the D-plate near the resonant frequency of the RF cavity. (The D-plate is grounded, but is not shown in Figure 29.)

[0187] The variable reactance element 1308 may be a capacitor formed by a plate 1312 and the surface 1316 of the internal conductor 1300. The plate 1312 is movable along a direction 1314 toward or away from the surface 1316. The capacitance of the capacitor changes as the distance D between the plate 1312 and the surface 1316 changes. For each frequency range swept for a single particle energy, the distance D is at a set value, and to change the frequency range, the plate 1312 is moved in accordance with the change in the energy of the output beam.

[0188] In some embodiments, the inner conductor 1300 and outer conductor 1302 are formed from a metallic material such as copper, aluminum, or silver. The blade 1310 and plate 1312 may also be formed from the same or different metallic material as the conductors 1300 and 1302. The coupling device 1304 may be a conductor. The variable reactance elements 1306 and 1308 may have other forms and be coupled to the deep plate 100 in other ways, thereby performing RF frequency sweep and frequency range change. 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.

[0189] The control of the gantry, patient support, active beam shaping elements, and synchrocyclotron used in the treatment session is achieved by appropriate therapeutic control electronics (not shown).

[0190] The control of the particle beam therapy systems and their various features described herein may be carried out using hardware or a combination of hardware and software. For example, a system like the one described herein may comprise various controllers and / or processing devices located at various locations. A central computer can coordinate the operation between the various controllers or processing devices. The central computer, controllers, and processing devices may execute various software routines to control and adjust testing and calibration.

[0191] System operation may be controlled, at least in part, by using one or more computer program products, such as one or more computer programs explicitly embodied in one or more non-temporary machine-readable media, for execution by or control of one or more data processing devices, such as programmable processors, computers, multiple computers, and / or programmable logical components.

[0192] Computer programs can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including standalone programs or modules, components, subroutines, or other units suitable for use in a computing environment. Computer programs can be deployed to run on a single computer, or on multiple computers located in a single site, or distributed across multiple sites and interconnected by a network.

[0193] Actions relating to steps that perform all or part of the operation of the particle beam therapy system described herein may be performed by one or more programmable processors that execute one or more computer programs to perform the functions described herein. All or part of these operations may be performed using dedicated logic circuits, such as FPGAs (field-programmable gate arrays) and / or ASICs (application-specific integrated circuits).

[0194] Processors suitable for executing computer programs include, for example, general-purpose microprocessors and dedicated microprocessors together, and any one or more processors in any type of digital computer. Generally, processors receive instructions and data from read-only storage, random-access storage, or both. The elements of a computer (including servers) include one or more processors for executing instructions and one or more storage devices for storing instructions and data. Generally, a computer also includes one or more machine-readable storage media, such as high-capacity PCBs, for storing data, e.g., magnetic disks, magneto-optical disks, or optical disks, or are coupled to operate in a manner that allows them to receive data from or transfer data to or both. Non-temporary machine-readable storage media suitable for embodying the instructions and data of computer programs include, for example, semiconductor storage devices, e.g., EPROM, EEPROM, and flash storage devices, magnetic disks, e.g., internal hard disks or removable disks, magneto-optical disks, and all forms of non-volatile storage, including CD-ROM and DVD-ROM disks.

[0195] Any “electrical connection” as used herein may include a direct physical connection or intervening components, but may nevertheless imply a wired or wireless connection that allows electrical signals to flow between connected components. Any “connection” involving an electrical circuit as referred to herein is an electrical connection unless otherwise specified, and is not necessarily a direct physical connection, regardless of whether the word “electrical” is used to modify “connection.”

[0196] Two further embodiments described above can be used in appropriate combinations in a suitable particle accelerator (e.g., a synchrocyclotron). Similarly, two further individual features of the embodiments described above can be used in appropriate combinations.

[0197] Elements of different embodiments described herein may also be combined to form other embodiments not specifically mentioned above. Elements may be removed from the processes, systems, apparatus, etc. described herein without adversely affecting their operation. Various separate elements may be combined into one or more individual elements to perform the functions described herein.

[0198] The exemplary embodiments described herein are used in conjunction with or not limited to the exemplary particle beam therapy systems described herein. Rather, the exemplary embodiments may be used within a suitable system that guides accelerated particles to output.

[0199] Other implementations not specifically described herein also fall within the scope of the following claims. [Explanation of Symbols]

[0200] 10 Treatment Systems 40 Leaf 40a, 40b, 42a, 42b coil set 50 Height 55 Tongue and groove features 56 Curved end 100 Magnetic Yoke 102 Drawer Channel 105 Particle Accelerator 106 Scanning System 108 Scanning Magnet 109 Ionization chamber 110 Energy Degrader 115 Range Modulator 116 Plate 116a Plate 117 Arrow 118 Current Sensor 122 Magnetic System 138 Drawer Channel 140 Annular Superconducting Coil 142 Annular Superconducting Coil 144 Magnetic pole face 146 Magnetic pole face 170 Low temperature holding tank 171 Support points 173 Support points 181, 183 Half 184 Return flux 186 Volume section 190 Particle Source 191 High-Frequency Drive System 192 Geometric Center 200 processes 230 Beam movement 233 layers 390 Cathode 392 Cathode 393 Gas pipeline 394 tube 399 Hydrogen supply unit 400 Charged Particle Beam Therapy System 402, 404, 406 High-temperature / low-temperature support straps 402 Beam-generating particle accelerator 404 Rotary Gantry 406 patients 408 S2 Fiberglass Link 408, 410 Legs 412, 414 bearings 416 Steel trusses, truss structures 418 Treatment Area 420 RPM range 422 floors 424 Vault 432 Horizontal rotation axis 442 vertical axis 480, 482 Approximately parallel spans 500 Deep Plate 502 Dummy 503, 505 Semicircular surface 507 Space 507, 509 Beam forming elements 509 Duct 514 Magnetic Shield 516 Space 517 A layer of ferromagnetic material (e.g., steel or iron) 525 Beamforming System 602 System 604 Synchrocyclotron 605 Rotary Gantry 606 Patient Support 622, 624 Counterweight 700 Applicable opening 701 Leaf 704 Treatment area 706 Placement 707 Placement 708 yen 711 Beam Spot 713, 714, 715 Carriage 720 trucks 722 Rod 723 Rod 725 Motor 726 Motor 730 Motor 731 Lead screw 732 Housing 735, 736 Leaf 735a Leaf 735b Leaf Stick 735c Lead screw nut 735d Lead screw 735e Thrust Bearing Assembly 735f joint 735g motor 735h Bearing Block 735i Sleeve Bearing Pin 735j sleeve bearing 735k Motor Mount Block 750 Leaf 751 Shaft 770 Examples 771 patients 771a beam 910 Treatment System 912 accelerator 914 Particle (e.g., proton) beam 916 Scanning Unit 916 Scattering Units 918 Monitoring Unit 920 Energy Degrader 922 Body 922′ Body or body part 924 Target volume section 926a~926i layer 928 Irradiation direction 930 Target volume section 932 Control device 1012 Magnetic System 1035, 1037 curve 1300 Inner conductor 1302 Outer conductor 1304 Power Coupling Devices 1306, 1308 Variable reactance elements 1310 Blade 1312 Plate 1314 direction 1316 Surface 1400 Leaf 1401 Radiation Spot 1402 Placement 1420 Curved Track 1421 Particle beam 1422 Source 1422 Particle beam 1423 place 1425 Placement 1426 arrangement 1428, 1429 Leaf 1431 Straight end (or "front part")

Claims

1. A collimation device comprising a primary carriage and two secondary carriages, The secondary carriage holds a structure that is movable within the beam field of the particle beam, the beam field comprises a range in which a magnet can deflect the particle beam relative to the irradiation target, and the structure is movable as the particle beam moves within the beam field to generate a shape for trimming at least a portion of the particle beam before it reaches the irradiation target. In the collimation device, the primary carriage is coupled to two secondary carriages, and the primary carriage controls the movement of the two secondary carriages relative to the irradiation target in a first direction which is a first orthogonal coordinate direction with respect to the collimation device, The primary carriage and the secondary carriage are controllable to follow the movement of the particle beam in order to position the structure within the beam field. The structure blocks the particle beam in a region smaller than the entire beam field. A collimation device characterized in that the two secondary carriages each comprise a first carriage comprising a first set of the structure and a second carriage comprising a second set of the structure, wherein the first carriage is movable in a second direction relative to the irradiation target, the second direction being a second orthogonal coordinate direction with respect to the collimation device, the first set of the structure is movable forward and backward relative to the first carriage in the second direction, the second carriage is movable relative to the irradiation target in the second orthogonal coordinate direction, and the second set of the structure is movable forward and backward relative to the second carriage in the second orthogonal coordinate direction.

2. The collimation apparatus according to claim 1, characterized in that the shape that can be generated is a shape for trimming a portion of each spot of the particle beam, or a shape for trimming a region consisting of multiple spots of the particle beam.

3. The collimation device according to claim 2, characterized in that the area of ​​the region consisting of a plurality of spots is substantially the same as the area of ​​two of the spots.

4. The collimation device according to claim 2, characterized in that the area of ​​the region consisting of a plurality of spots is substantially the same as the area of ​​the three spots.

5. The collimation device according to claim 2, characterized in that the area of ​​the region consisting of the multiple spots is substantially the same as the area of ​​the four spots.

6. The collimation device according to claim 2, characterized in that the area of ​​the region consisting of the multiple spots is substantially the same as the area of ​​the five spots.

7. The collimation device according to claim 2, characterized in that the area of ​​the region consisting of a plurality of spots is smaller than the entire beam field.

8. The collimation device according to claim 1, characterized in that the structure is movable relative to the irradiation target in order to form a shape that approximates at least partially curved.

9. The collimation device according to claim 1, characterized in that the collimation device includes one or more motors for controlling the movement of the structure.

10. The collimation device according to claim 1, characterized in that the first orthogonal coordinate direction is defined as the vertical direction and the second orthogonal coordinate direction is defined as the horizontal direction.

11. The collimation device according to claim 1, characterized in that at least one of the secondary carriages is rotatable relative to the primary carriage.

12. The collimation device according to claim 1, characterized in that the collimation device is rotatable with respect to the irradiation target.

13. At least a few of the aforementioned structures have flat edges, The collimation device according to claim 1, characterized in that the two secondary carriages are attached to a curved track and are movable along the track.

14. The aforementioned structure is equipped with a leaf, The collimation device according to claim 1, characterized in that at least a number of the leaves have a width different from the width of the remaining leaves.

15. The collimation device according to claim 14, characterized in that at least a plurality of the leaves have a width of three times or more the width of the remaining leaves.

16. The primary carriage is made movable in the first orthogonal coordinate direction for various movements of the particle beam. The collimation apparatus according to claim 1, characterized in that the secondary carriage is movable in the second orthogonal coordinate direction for various movements of the particle beam.

17. The collimation device according to claim 1, characterized in that the first set of the structure and the second set of the structure are movable to generate a formation having the same opening as the opening of the fixed opening device.

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