Quality assurance system for particle radiation therapy

Abstract

A quality assurance system for radiation therapy (2) used in a therapy apparatus (100), the therapy apparatus (100) comprising a therapy table (101) and a particle radiation apparatus (103) having a radiation emission head (104) for particle beam radiation, the quality assurance system comprising:-a detector device (3), the present invention relates to a treatment device (100) comprising at least one detection module (8) configured for measuring gamma radiation emitted by a target object subjected to a particle radiation beam, and a support mechanism (7) on which the at least one detection module (8) is mounted, the support mechanism (7) comprising a base (12) configured for coupling to a treatment table (101) of the treatment device (100), and at least one detection module support structure (18) pivotally coupled to the base (12) via a pivot coupling (16).

Description

[0001] The present invention relates to a system for quality assurance of particle radiation therapy, and in particular to a system for measuring secondary radiation caused by particle-target interactions. The target may include but is not limited to patients, animals, phantoms of various materials, cadavers, mixed or heterogeneous tissues, organs, or other biological samples.

[0002] During radiation therapy, the patient is irradiated with a particle beam from several different angles, typically through relative movement (translation and / or rotation) between a patient couch (on which the patient is placed) and a rotating beam-guiding structure (gantry). The precision and accuracy with which the irradiation target can be delivered to the patient with the desired dose distribution depends primarily on two types of error sources: (i) External and mechanical factors Alignment: How well the different devices are aligned to a common virtual reference point (the "isocenter"). Examples of such devices are the treatment couch on which the patient is placed, the gantry, optical guidance systems used for device calibration and quality assurance, or imaging devices used to verify patient positioning in direct relation to radiation exposure.

[0003] Beam delivery: Errors in beam position, energy, direction, current, dwell time per spot, or shape, for example, can result in over- or under-dose.

[0004] Target setup error: A difference in the positioning of the target volume relative to the intended position or the position assumed in the treatment plan. This can be caused by factors such as displacement or rotation of the target or deformation of the target.

[0005] (ii) Target modeling factors Unlike photon radiation therapy using X-rays or gamma rays, particle radiation therapy (particularly when using protons or ions) is very sensitive to range uncertainty. Unlike an exponentially decreasing depth-dose curve, the depth-dose distribution of charged particles slowing down in a material ends with a sharp Bragg peak: a very high dose is delivered just before the particles come to rest. This has the advantage that the dose from particles delivered from one or more angles, or from a combination of different energies, can be tailored to produce the desired dose in the target area while minimizing the dose to, for example, healthy tissue. Furthermore, accurate modeling of the particle deceleration process within the target is crucial for accurately predicting where the particles will come to rest. Modeling errors can arise from, for example, X-ray or CT image artifacts, changes in the patient's anatomy during treatment, variations in how the target is positioned and secured on the treatment couch, or errors in the treatment planning system (TPS)'s prediction of the stopping power of various parts of the target.

[0006] Quality assurance (QA) equipment is used to assess, quantify, and, as far as reasonably possible, eliminate or compensate for any clinically relevant effects of various error sources through calibration. The QA process should be performed regularly to provide confidence that the patient receives the intended dose distribution. An example is described below.

[0007] Beam QA measurement One type of QA measurement involves those designed to verify that relevant properties of the beam are within acceptable ranges. These properties can be the size, shape (profile), and position of individual beams or spots, typically measured near the isocenter in a plane orthogonal to the beam axis. Other measurements can be aimed at calibrating or verifying the calibration of beam intensity monitors or dose monitors, which are used to determine when the allocated number of particles has been delivered to a minimum subset ("spot") of the treatment plan. Such measurements are critical to ensuring the delivery of an acceptable dose distribution and typically require sub-millimeter and sub-percent precision and accuracy for spatial and charge measurements, respectively.

[0008] QA equipment based on destructive ionization measurements US2010 / 0108901 discloses a multi-slice ionization chamber designed to measure the one-dimensional depth-dose distribution of a proton beam by intercepting, absorbing, and stopping the proton beam. The device can be placed on a treatment couch, facing the beam, and can measure the depth-dose curve of a single proton beam spot ("Bragg curve") or the combined depth-dose curves of several beam spots that form a spread-out Bragg peak. This type of prior art suffers from the disadvantage of being destructive: it is impossible to non-invasively measure the dose distribution in the target. By transmitting a proton beam through the target, compared to directly transmitting a proton beam of the same initial energy through the multi-slice ionization chamber, the total beam energy loss in the target can be measured indirectly, and the shift in the Bragg curve can be measured. However, this method cannot detect internal variations in the beam stopping power within the target along the beam axis: the device can only measure the overall stopping power of the target. Depth dose measurement devices can be used to generate tomographic stopping power images of the target simply by repeatedly measuring the overall stopping power from multiple directions ("proton tomography"). The disadvantage is that this would require a large number of measurements, combined with repeated repositioning of the target or the equipment setup, since the equipment can only intercept the beam from a single direction (perpendicular to the ionization chamber).

[0009] The device disclosed in US2010 / 0108901 is unable to intercept proton beams delivered from the many different directions requested in a typical clinically relevant treatment plan. Furthermore, the device has a limited aperture, a few centimeters in diameter, within which the beam can be intercepted. This is smaller than the available cross-section of the scanned beam field, which can span 20 × 20 cm or more, depending on the beam delivery system (BDS).

[0010] Another QA device, based on multiple small ionization chambers arranged in a plane, is disclosed in EP1907062B1. This and similar devices can be used to verify that the transverse coordinates of the scanned beam are as expected, for example, in a plane containing the isocenter. However, this type of device also does not provide a direct measurement of how or where the beam is decelerating within the target.

[0011] Proton tomography An example of a device specifically for performing clinical proton tomography on a patient is disclosed in US2011220794A1. Disadvantages of this device include: - the target must be illuminated from many different directions by rotating the device's detection elements in unison with the gantry's rotation, whereby the device needs to be mechanically mounted to the gantry to ensure that it rotates in unison with the gantry, or, alternatively, the device must be integrated with the gantry's rotation control system to ensure that the device and gantry motion are coordinated, - the available proton beam energy must be high enough to allow the beam to completely pass through the entire target and enter the detection elements downstream of the target, which may significantly increase the lateral spot size of the proton beam when it reaches the detector downstream of the target due to multiple Coulomb scattering in the target and the air gap, effectively limiting the spatial resolution of the tomographic stopping power image, - It is not possible to detect the stopping power in the interior region of a target without acquiring a complete tomographic data set from around the target.

[0012] Consistency check A "constancy check" is a measurement performed to verify that a reference rotation plan is transmitted consistently, for example after a hardware or software upgrade or machine maintenance, or as part of a regular routine control. Typically, this is done by transmitting the treatment plan under well-defined conditions and ensuring that the readings from the various QA devices are consistent with the earlier measurements. A disadvantage of existing QA devices is that such measurements can only be performed with a limited set of beam parameters. In particular, QA devices in the referenced prior art do not allow irradiation from any direction, but are limited to "frontal" irradiation. It is challenging and impractical to verify that the position and range of, for example, a scanned beam is as expected from a wide, or even continuous, range of gantry angles. Such QA measurements are particularly relevant for arc therapy, involving continuous or quasi-continuous beam delivery as the gantry rotates and / or the treatment table moves.

[0013] Patient-specific QA Patient-specific QA can include transferring the patient-specific treatment plan into the target. After transfer, a log file from a device such as a beam monitor inside the radiation emission head can be used to recalculate what the delivered dose distribution will look like in the patient based on the same patient-specific model used to design the treatment plan. The log file can contain information about the number of particles actually delivered per point or the measured positions of the scanned beam. Patient-specific QA can also include transferring the patient-specific treatment plan into a water tank, such as one with a point ionization chamber or a 2D ionization chamber. The measured dose is compared to the recalculated dose distribution in the water. This QA process only addresses uncertainties in the beam delivery, without potential errors in the anatomical model of the patient / target that could lead to, for example, overshoot or undershoot.

[0014] More generally, it is important to ensure that the delivered radiation is spatially and dosimetrically accurate, accurately covering the intended treatment area taking into account errors and uncertainties arising in the chain of steps between the intended radiation therapy and the delivered radiation therapy, which chain includes imaging of the region of interest, modeling of the tissue to be treated and the surrounding area of interest, modeling of the irradiation beam, treatment planning, setup and positioning of the radiation therapy equipment, and finally the actual spatiotemporal delivery of the radiation beam.

[0015] As previously mentioned, various quality assurance systems are used to control and calibrate radiotherapy treatments to account for certain aforementioned errors and uncertainties. At least in the literature, some quality assurance devices are designed to measure radiation beam flux during treatment, while other quality assurance devices are primarily used in factory or pre-treatment settings to calibrate radiotherapy equipment prior to treatment. However, such devices typically do not take into account the actual treatment setup, such as the radiotherapy machine and treatment table and gantry components. However, the actual treatment setup may affect the radiation beam flux and its measurement.

[0016] Installing and setting up quality assurance systems in traditional systems is complex and time-consuming, which is not only costly but also makes it difficult to implement quality assurance (QA) systems during or just before treatment. Similarly, performing constancy check measurements for QA purposes or evaluating the correctness of the treatment planning system's target modeling from many different beam directions is time-consuming, requiring the use of several different measurement devices and many manual steps, especially when using third-party QA equipment that is neither mechanically integrated into the irradiation room nor required to be used with the treatment device control system.

[0017] One of the problems that the present invention seeks to solve is the ability to conveniently set up a QA system in an irradiation chamber and deliver a proton beam from almost any angle without requiring any modifications to the existing irradiation chamber equipment.

[0018] In view of the above, an object of the present invention is to provide a quality assurance system for particle radiation therapy that is quick and easy to implement and also ensures accurate calibration or verification of particle radiation therapy to identify or reduce errors and uncertainties between expected and delivered dose distributions.

[0019] It would be advantageous to provide a quality assurance system for particle body therapy that is flexible and can be easily adapted to various beam delivery configurations and treatment tables.

[0020] It would be advantageous to provide a quality assurance system for particle radiation therapy that is easy and economical to install and remove in an irradiation room, particularly relative to conventional particle radiation therapy equipment.

[0021] It would be advantageous to provide a detection system for a quality assurance system for particle radiation therapy that is compact, easily and quickly installed and uninstalled, and also allows accurate measurement of target activation in a representative treatment setting.

[0022] The objects of the present invention are achieved by providing a system according to the independent claim. The dependent claims set out various advantageous features of embodiments of the invention.

[0023] The present invention discloses a quality assurance system for radiotherapy, which is used in a treatment device comprising a treatment table and a particle radiation device having a radiation emitting head for particle beam irradiation, comprising: - a detector arrangement comprising at least one detection module configured to measure gamma radiation emitted by a target object subjected to a beam of particle radiation, and - a support mechanism on which the at least one detection module is mounted, the support mechanism comprising a base configured for removable coupling to a treatment table of the treatment device, and at least one detection module support structure pivotally coupled to the base via a pivot coupling.

[0024] In an advantageous embodiment, the detection module support structure has a substantially C-shape with an open section configured for transmission of a particle beam emitted by a radiation emitter of the particle irradiation device through the open section.

[0025] In one embodiment, the detection module support structure has at least two opening sections configured for the particle beam emitted by the radiation emitter of the particle irradiation device to transmit through the opening sections.

[0026] In an advantageous embodiment, the or at least one opening segment may advantageously have a width that is greater than the width of the treatment table, in order to allow for a vertical mounting of the detector module around the treatment table.

[0027] In an advantageous embodiment, the support mechanism includes a support arm that couples the detection module support structure to the pivot coupling and positions the detection module support structure relative to the pivot coupling such that a central axis of the support structure is aligned with an axis of rotation of the pivot coupling.

[0028] In an advantageous embodiment, the pivot coupling comprises a motor configured for motorized rotation of the detection module about the axis of rotation of the pivot coupling.

[0029] In an advantageous embodiment, the support mechanism of the detection device further comprises a sliding coupling configured for translating the pivot base of the pivot coupling relative to the base, the sliding coupling or for example comprising a track on the base which engages a complementary track or channel on the pivot base.

[0030] In an advantageous embodiment, the system further comprises a detector transport device comprising a cart having a support surface for removably mounting the detector transport device thereon, the cart having ground engaging members, e.g. in the form of wheels or rollers, allowing the cart to be moved to and from a treatment device configured for positioning the detector device for coupling thereto.

[0031] In an advantageous embodiment, the detector transporter cart comprises a position adjustment mechanism for moving the detector transporter onto or away from the supporting surface of the cart.

[0032] In an advantageous embodiment, the system further comprises a lifting mechanism for transferring the detector device from the cart to the treatment table.

[0033] In an advantageous embodiment, the system further comprises an adapter interface mountable on a treatment table of the treatment apparatus, the detector device being mountable on the adapter interface for coupling to the treatment table.

[0034] In an advantageous embodiment, the adapter interface and the trolley have mutually engaging fastening elements for storing the adapter interface on the trolley when the trolley is not in use.

[0035] In an advantageous embodiment, the cart comprises guardrails receiving ends of said detection module support structure therein for protecting the detection module when the detector device is mounted and loaded on the detector transport device.

[0036] In an advantageous embodiment, the system further comprises a phantom device comprising a body and one or more cavities formed within the body, the body comprising any one or more selected from the group consisting of polyethylene (PE), HE solid water, virtual water, RW1, RW3, polystyrene, blue water or polymethyl methacrylate (PMMA), or other low Z materials having a typically short-lived radioactive isotope produced by the beam, or in a manner similar to that of a radioactive isotope such as a radioactive isotope. 18 O. 63 Cu or 68 Zn has an isotope with a high probability of emitting a positron after the radiation beam interacts.

[0037] In an advantageous embodiment, the cavity of the phantom device comprises holes and / or grooves formed in the material of the body, said grooves may comprise transverse grooves and axial grooves.

[0038] In an advantageous embodiment, the phantom device comprises a substantially flat front face, and side faces that are substantially perpendicular to the top face or the front face and connected to the top face or the front face via chamfered or rounded corner faces.

[0039] In an advantageous embodiment, the side faces are substantially cylindrical or polygonal.

[0040] In an advantageous embodiment, the system further comprises a computing system, which is connectable to the detector arrangement for acquiring the measurement data from the detection module and for controlling the detector arrangement.

[0041] In an advantageous embodiment, the computing system is configured to output at least one distal decay coordinate of the measured activation, the distal decay coordinate corresponding to a falling edge of the measured activation along the particle beam axis.

[0042] In an advantageous embodiment, the computing system is configured to output coordinates of the measured at least one rising edge of the activation, the rising edge coordinates corresponding to an entry point of the particle beam in the irradiated target.

[0043] Also disclosed herein is a treatment apparatus in combination with a quality assurance system for radiation therapy according to any preceding embodiment, wherein, in use, the detector apparatus is mounted on a treatment table of the treatment apparatus, and a radiation emission head of the treatment apparatus is positioned for transmitting a particle radiation beam through an opening in a detection module support structure, the position of the detection module support structure being adjusted for alignment with the radiation emission head through the opening in the support structure.

[0044] In an advantageous embodiment, the detection module support structure is positioned within a tunnel of the treatment device, in which tunnel the radiation emitting head is mounted.

[0045] In an advantageous embodiment, the detection module support structure is dynamically coupled to the base and is configured to rotate in synchronization with the radiation emitting head of the treatment device.

[0046] In an advantageous embodiment, a computing system of a quality assurance system for radiation therapy is connected to at least one of a treatment planning system module and a beam delivery system of a treatment apparatus for receiving information about targets, treatment plans, irradiation progress and log files from an irradiation session.

[0047] Other objects and advantageous features of the present invention will be apparent from the claims, detailed description and accompanying drawings, in which: Figure 1 is a block diagram of a quality assurance system for radiotherapy according to an embodiment of the present invention; Figure 2a is a schematic representation of a treatment apparatus showing an accelerator, magnetic elements of a rotating gantry, a radiation emitting head including a monitor, a scanning particle beam, and a phantom apparatus on a treatment table; Figure 2b is a perspective view of a detector device of a quality assurance system for radiotherapy according to an embodiment of the present invention, the detector device being installed in a conventional treatment apparatus including a treatment table and a particle radiation device; Figure 3a is a perspective view of a detector device of a quality assurance system for radiation therapy according to an embodiment of the present invention; Figure 3b is similar to Figure 3a The view shows the Figure 3a a detection module and a support structure of the detector assembly in a rotational and translational position relative to the base compared to a position in; Figure 3c is a schematic representation of the detector arrangement seen in the direction of the rotation axis of the detector module; Figure 3d is a perspective view of a detector device having two detection modules according to an embodiment of the present invention, wherein the support structure is configured to have two open sections between the detector modules; Figure 4a and 4b is a perspective view of a detector transport device of a quality assurance system for radiation therapy according to an embodiment of the present invention; Figure 5a Is installed in Figure 4a and 4b The detector transport device Figures 3a-3c A perspective view of a detector device and a treatment table with the detector device positioned thereon; Figure 5bis a perspective view of a treatment table and an adapter interface of a detector device mounted thereon according to an embodiment of the present invention; Figure 5c is an exploded perspective view of a detector assembly mounted on a treatment table with an adapter interface positioned therebetween according to an embodiment of the present invention; Figure 6a is a perspective view of a phantom apparatus for a quality assurance system for radiotherapy according to an embodiment of the present invention; Figure 6b is a simplified schematic representation of a phantom device and an associated graph showing activation intensity over the length of the phantom device having a cavity formed therein and corresponding rising and falling points along the beam trajectory; Figure 7a is a flow chart illustrating steps for acquiring measurement data in a quality assurance system for radiotherapy according to an embodiment of the present invention; Figure 7b is a simplified block flow diagram illustrating steps for checking the constancy of measurements performed by a quality assurance system for radiation therapy according to an embodiment of the present invention; Figure 8 is similar to Figure 7a Flow chart further illustrating the analysis and output steps in the quality assurance system for radiotherapy according to an embodiment of the present invention; Figure 9 is a block flow diagram showing an example of steps for processing a measurement of a penetration depth of a particle beam in a target object according to an embodiment of the present invention; Figure 10 is similar to Figure 9 pictorial representation of a variation of .

[0048] With reference to the accompanying drawings, Figure 1 2 , a quality assurance system 2 for radiation therapy according to an embodiment of the present invention is shown, which is used together with a treatment apparatus 100. The quality assurance system 2 for radiation therapy comprises a detector device 3 having a detection module 8, and a computing system 4 connectable to the detection module for acquiring and analyzing measurement data output by the detection module.

[0049] The computing system 4 may also include a control module for controlling and configuring the detector arrangement and the data acquisition process. The computing system may further include a user interface and a module for image reconstruction to visualize relevant quantities in the target body, such as treatment dose and distribution, activation or stopping power.

[0050] The computing system may also include, or be connected to, a database, a beam delivery system (BDS) 107, and a treatment planning system (TPS) 108, and receive and transmit data therewith. The treatment planning system includes information about the target to be treated and the radiation beam delivery plan. The TPS includes software for generating a treatment plan, which typically may include a list of proton beam spots to be delivered based on available target information. The TPS is separate from the beam delivery system and control system that control irradiation. The computing system can therefore be connected to the treatment planning system, which can be used to provide target information and generate a treatment plan. The beam delivery system of the treatment apparatus 100 executes and monitors the treatment plan delivery process, which includes controlling the particle radiation device 103 to deliver radiation therapy to the patient or target.

[0051] The treatment apparatus can have various configurations, as is known in the art. In the illustrated example, the treatment apparatus includes a treatment table 101, also known as a patient treatment couch, which can be mounted on a robotic arm 102, a particle irradiation device 103 including a particle accelerator 112, a gantry 105 having beam guiding, focusing, and deflection magnets 109, and a radiation emission head 104 including a beam monitor 110.

[0052] In a variation, treatment table 101 can be configured with up to six degrees of freedom via robotic arm 102: three-dimensional translation and rotation (pitch, roll, and yaw) independent of gantry 105. This allows irradiation of a patient or target positioned on treatment table 101 from a range of orientations by adjusting the position and orientation of treatment table 101 and the angle of the gantry about its rotational axis B. In another variation, radiation device 103 does not include a gantry, and radiation emission head 104 remains stationary, emitting, for example, a horizontal or vertical beam into the irradiation chamber. Other combinations of relative motion are also possible, such as mounting accelerator 112 directly on a rotating structure.

[0053] More specifically refer to Figures 2a to 5b The quality assurance system 2 for radiotherapy according to an embodiment of the present invention may further include a detector transport device 5 for moving the detector device 3 into and out of a treatment setting, for example, into and out of a treatment device 100 or an irradiation room.

[0054] The detector transport device 5 comprises a cart 9 mounted on wheels 27 , which includes an upper support surface or rails or other support elements on which the detector device can be mounted when not mounted in the treatment device 100 .

[0055] The quality assurance system 2 for radiotherapy according to an embodiment of the present invention may advantageously further comprise a phantom device 6, which can be used to perform measurements and acquire data from the particle radiation beam emitted by the particle radiation device 103 of the treatment apparatus 100. The phantom device is made of a material and includes features intended to simulate a patient's body region and / or provide a specific target reference volume, which in particular allows for an estimation of the behavior of the particle radiation beam in a body part of a living subject during treatment.

[0056] The detector device 3 comprises one or more detection modules 8 mounted on a support mechanism 7 .

[0057] The detection module 8 is configured to measure secondary radiation, mainly in the form of gamma rays, emitted by the target subjected to particle irradiation.

[0058] Gamma ray detection modules are well known and may advantageously include in the present invention the configuration and features as described in WO 2021140233. Other gamma ray detection modules well known in the art may also be used within the scope of the present invention.

[0059] In one embodiment, the detection modules 8 are advantageously arranged in a ring around the central axis. Figures 3a to 3c As shown, the ring has an opening such that it forms a substantially C-shape, the opening allowing the radiation emitting head 104 of the particle irradiation device 103 to emit a particle radiation beam 111 through the opening.

[0060] In another embodiment, the detection module may be arranged to provide an opening to allow the radiation emission head 104 of the particle irradiation device 103 to emit the particle radiation beam 111 on the opposite side through the opening. Figure 3d In the embodiment shown, at least one pair of detection modules 8 are positioned on the support structure 7 in a spaced-apart, opposing manner, leaving openings on opposite sides (top and bottom sides in the illustration).

[0061] In treatment plans involving relative rotation of the radiation head about the central axis, the detection module support structure 18 is configured to rotate in such a way as to align the opening of the ring with the particle radiation beam position, in other words, with the position of the radiation emitting head 104 .

[0062] In a treatment apparatus 100 comprising a tunnel surrounding a treatment table 101 , the radiation emitting head 104 can move around the tunnel, wherein the outer diameter D of the detection module support structure 18 on which the detection module 8 is mounted is out Configured to fit within the tunnel of treatment device 100.

[0063] The inner diameter D of the detection module support structure 18 inIt can be advantageously configured to surround a treatment table 101 that can be accommodated within the inner diameter of the detection module support structure.

[0064] The opening of the detection module has a width D gap , which can be advantageously configured to exceed the width of the treatment table 101 so as to mount the detection device on the treatment table 101 in a direction perpendicular to the surface of the treatment table, such as Figure 5c shown.

[0065] The support mechanism 7 of the detection device includes a base 12 to which a support arm 14 is movably coupled, and a detection module support structure 18 is fixed to the support arm 14. The support arm 14 is advantageously coupled to the base via a pivot coupling 16 having a center of rotation corresponding to the central axis A of the detection module support structure 18, such that when the support arm 14 pivots about the pivot coupling 16, the detection module support structure 18 performs a circular motion within its own envelope. The support mechanism 7 may advantageously further include a sliding coupling 19, for example comprising a track mounted on the base 12, the track configured to facilitate translation of a pivot base 17 of the pivot coupling 16 in an axial direction A. The detection module 8 can thus rotate in a circular manner about the central axis A and can also translate in the direction of the central axis. This translation allows for precise axial positioning of the detection module over the target area and, if the radiation emission head 104 or the treatment table 101 is translatable in the axial direction relative to the central axis A, also allows for corresponding translation of the detection module 8. This translation also facilitates access or unobstructed viewing of the target, if desired, for example if the target is to be imaged in situ with orthogonal X-ray panels.

[0066] The radiation emission head or an element on the radiation emission head, such as a range shifter, can also be translated in the beam direction to reduce the gap between the element and the target. This translation advantageously allows beam irradiation with minimal gap by clearing the gap from the detection module support structure 18 and support arm 14.

[0067] The pivot coupling 16 preferably comprises a motor for electrically actuating the rotation of the detection module 8. The sliding coupling 19 may also comprise an electrically powered device such as a linear nut and screw actuator for translation of the detection module 8 relative to the base 12.

[0068] In a variant, the pivot coupling and / or the sliding coupling may also be completely mechanical and manually operable, in particular for use with a particle irradiation device 103 having a radiation emitting head 104 that is not dynamically moved during particle beam irradiation.

[0069] In a variant, the plurality of detection modules may be independently movable, for example by means of independently pivoting support structures or by means of a plurality of articulated positioning arms.

[0070] The detector device advantageously comprises a support mechanism 7 with a base 12 enabling the detector device to be coupled to a treatment table 101 in a treatment setting and in particular for example mounted on the treatment table 101 , ie within the treatment device 100 , in a position corresponding to that for patient treatment.

[0071] The quality assurance system for radiotherapy may advantageously further include an adapter interface 20, which forms an interface between the base 12 of the detector device 3 and the treatment table 101, the adapter interface 20 being configured to adjust the position of the base 12 relative to the adapter interface 20 via a base positioning element 32. The adapter interface may include a fixing member 35 for fixing the adapter interface to the treatment table 101, thereby providing different fixing members for treatment tables with different standards, so that the detector device 3 can be coupled to different treatment tables 101 without modifying the base 12.

[0072] In the example shown, the treatment table 101 comprises position markings or fixing elements 106 on its side edges, which allow positioning and spatial registration of the patient and / or the adapter interface 20 relative to the particle radiation device 103 and / or the robotic arm 102 .

[0073] The cart 9 may advantageously include elements for securing and stowing the adapter interface 20 on the cart, such as on a side of the cart for convenience.

[0074] The cart 9 may include a cabinet 34 for storing various components of the quality assurance system 2 for radiotherapy treatment, and may also support the computing system 4 and have space for storing one or more phantom devices 6. The cart may also support a power source such as a battery, or provide a plug and / or cable for connecting to a power source, for example for connecting to the detector device 3.

[0075] The cart 9 may further comprise a displacement mechanism 25, which comprises, for example, a height adjustment mechanism and an optional translation mechanism, for moving the detector device 3 of the cart 9 away from or onto the treatment table 101. Prior to such operation, the adapter interface 20 may be mounted on the treatment table 101, as shown in FIG. Figure 5b shown.

[0076] The cart 9 may further include a motorized or manually operated lifting mechanism (height adjustment mechanism) for lifting the detection device 3 from the cart to the treatment table 101. Alternatively, the treatment table 101 may have a lifting mechanism to adjust the height of the treatment table, and the lifting mechanism may also be used to lift the detection device 3 from the cart to the treatment table 101. In one variation, both the treatment table and the cart may each have a lifting mechanism.

[0077] When the detection device 3 is mounted on the cart 9 for storage or when not in use, the detection module support structure 18 can be positioned such as Figure 5a , in which the open end of the detection module support structure 18 is positioned within a protective rail 23 that provides protection for the support structure on the cart.

[0078] The phantom device 6 according to an advantageous embodiment of the present invention comprises a body 22 of a material, preferably of low average atomic number, and a plurality of cavities 24, which may comprise holes 26 and / or slots 28 formed in the body of the material. The material of the phantom device 6 may comprise any one or more commonly used phantom materials, such as polyethylene (PE), HE solid water, virtual water, RW1, RW3, polystyrene, plastic water, blue water, or polymethyl methacrylate (PMMA), or other materials having a generally short-lived radioactive isotope produced by the beam. The phantom device may also comprise any one or more materials having a high concentration of an isotope that has a high probability of emitting a positron after interacting with the proton beam, such as 18 O. 63 Cu or 68 The grooves 28 may include transverse grooves 28a and axial grooves 28b arranged transverse to the axial direction A, or grooves having both axial and transverse components (not shown). The body 22 may have a top or front surface 30 and side surfaces 31, which may, for example, have a generally cylindrical shape, although other non-axisymmetric or polygonal shapes may also be provided. The front or top surface 30 may be connected to the side surfaces 31 by rounded or chamfered corner surfaces 33. Both the front surface and the chamfered or rounded corner surfaces may be provided with cavities formed within the body of material.

[0079] The cavity 24 forms a region in which the particle radiation beam experiences negligible energy loss and can therefore be used as a spatial reference region for measuring secondary radiation caused by the interaction between the particle radiation beam and the material of the body 22, and can be configured with varying sizes, geometric arrangements, and densities to adjust the properties of the phantom device as the particle radiation beam passes therethrough. In variations, the phantom device can have a structure with different materials, including materials with different compositions and / or densities, formed together in layers or other 3-dimensional structures, for example, by additive manufacturing such as 3D printing, to more closely simulate a target object, for example, a body part containing a treatment target area.

[0080] Therefore, the diameter or width of the features of the phantom device 6 can be advantageously selected to maximize sensitivity to beam displacement from a desired position, or relative displacement between two or more irradiation treatments under comparison. This can be achieved, for example, by selecting the aperture diameter so that the aperture edge aligns with the maximum gradient in the beam's transverse profile. For a Gaussian beam profile, this corresponds to a width or diameter of 2σ. The beam width can depend on the beam energy. To this end, the phantom can advantageously feature apertures having a range of diameters, so that sensitivity to displacement can be maximized by selecting the appropriate aperture for the beam energy of interest.

[0081] like Figure 6b As schematically shown in FIG, the phantom device 6 may further include an internal cavity 24.

[0082] The material adjacent the hole, groove or cavity may advantageously be enriched in one or more isotopes selected to increase the available signal for imaging.

[0083] The cavity can be advantageously used to enhance sensitivity to displacement of the beam 111 along its axis (i.e., deviation in the beam penetration depth). The energy of the beam can be selected so that its distal attenuation region coincides with the proximal or distal surface of the cavity or recess. In a preferred embodiment, the maximum gradient of the expected distal attenuation coincides with the proximal or distal cavity surface. Figure 6b As shown, changes in beam energy can be measured as an increase or decrease in total activation detected downstream of the cavity or groove.

[0084] Advantageously, the precise dimensions and materials of the phantom device 6 and the intended beam trajectory are defined so that the intended beam range matches any beam energy among those available for clinical or quality assurance purposes. In a preferred embodiment, the surfaces at the beam incident point and the distal and proximal boundary surfaces of the cavity or recess along the beam trajectory are preferably all parallel to each other and orthogonal to the beam axis to avoid target activation upstream or downstream of any cavity or recess also associated with small unintended beam position displacements.

[0085] The phantom device 6 can be reproducibly placed on the treatment table using a docking structure similar to the adapter interface 20. The docking structure can be conveniently aligned with the treatment table position markings 106, thereby reducing positioning uncertainty of the phantom device relative to the treatment table. In one embodiment of the present invention, the adapter interface 20 extends from the base 12 along the treatment table 101 to also serve as a docking structure or support for the target.

[0086] Figure 7aA method for performing a constancy check according to an embodiment of the present invention is shown in FIG. A preferred embodiment of the method uses two or more independent irradiation sessions, for example, performed routinely for comparison with a baseline acquisition, or performed before and after maintenance or modification of the treatment device. The method can advantageously be implemented using a phantom device 6 to provide enhanced sensitivity to changes in the properties of the beam or the alignment of system components. In each irradiation session, the target is prepared in an appropriate manner. Depending on the target used, the preparation can, for example, include filling a water tank or fixing the tissue target. Imaging of the target can be performed to plan the beam delivery sequence. The treatment room, target, and detector device 3 are then set up for the irradiation session. The radiation beam is delivered according to the prepared sequence, and measurements are acquired using the detector device 3. The detector device 3 can advantageously use the parameters of the beam delivery as input to calculate the movement plan. Alternatively, the detector device 3 can implement a preset movement plan that provides sensitivity over the entire volume of the target or a volume of interest.

[0087] While the phantom device 6 can be used as a consistency target to improve measurement accuracy during constancy checks, the detector assembly 3 can also be advantageously used to assess uncertainty in TPS modeling of other targets, such as tissue samples or animal parts. As an example, the TPS can be used to construct a model of the target and a treatment plan to be delivered to the target. The simplest possible treatment plan will consist of a single beam spot. During or after treatment plan delivery, the computing system 4 can generate a 1-, 2-, or 3-dimensional image of the target activation detected by the detector assembly 3, potentially including time-dependent (spatiotemporal) information. The computing system 4 can output at least one distal decay coordinate 113 of the measured activation, corresponding to a falling edge of the measured activation along the beam axis. This distal decay point can be associated with a residual beam energy corresponding to the cutoff energy used to generate the radioisotope being imaged by the detector assembly. The computing system 4 can also output the coordinates of at least one rising edge 114 of the measured activation, corresponding to a beam entry point or surface irradiating the target, thereby providing an independent means of locating the target relative to the detector assembly 3.

[0088] The aforementioned remote decay method can be extended to detect residual beam energy along the beam axis by performing measurements with varying beam energies. In this case, it is advantageous to define a sequence of beam spots that are sufficiently well separated in the target to resolve the individual decay points. This can be achieved, for example, by using a rising sequence of beam energies, such that the decay point of each beam spot can be resolved from the residual activity of the previous beam spot. It is also possible to exploit the finite decay time of activated isotopes by transmitting beam spots separated by a sufficient time interval to allow for substantial decay of spatially overlapping distributions.

[0089] The method can also be used with a field of scanned beam spots to estimate the residual beam energy at locations on the beam scan plane.

[0090] The previously described methods can be combined to detect the residual beam energy in the target as a function of one-dimensional, two-dimensional, or three-dimensional position. This can be achieved, for example, by defining a sequence of layered beam spots with defined energies and coordinates in a beam scan plan, such that the distal attenuation of each energy layer or each layer is resolvable for each point in the scan plane.

[0091] The residual beam energy measurements obtained from the previously described methods can be compared with values calculated by existing treatment planning protocols in order to validate the target modeling assumed by these existing protocols. Figure 8 、 9 Figures 10 and 11 illustrate an embodiment of a process for performing an evaluation of a treatment planning system (TPS). Detector assembly 3 provides a measurement of the distal dropout location z_cutoff. The initial energy E_0 is assumed to be known from the beam delivery configuration, while the threshold energy for target activation, E_cutoff, is assumed to be known from the literature. TPS provides a calculation of the residual beam energy at a specified depth z_cutoff, or a calculation of the depth at which a specified residual beam energy, E_cutoff, is achieved. The consistency of the TPS calculations with the measurements can be assessed using either quantity. The TPS calculation of these quantities relies on its estimate of the stopping power integral, which incorporates a model of the beam delivery system, the target, and the interactions of beam particles in the target. Therefore, a comparison of the quantities calculated by the TPS with the quantities measured by the detector assembly 3 is an assessment of the accuracy of the modeling of these aspects that are relevant to clinical treatment planning.

[0092] Because the imaging activity endpoint is close to the peak dose deposition and beam range, the distal activity decay is insensitive to material variations at the distal end of the beam range. Therefore, it is advantageous to modify the treatment plan to expand the volume being probed. For example, the treatment plan can be modified to include energies higher than those used in the proposed clinical treatment. This allows the validity of modeling assumptions to be tested across the entire target volume associated with the planned dose deposition. Similarly, the number of particles per spot can be advantageously increased beyond that suitable for clinical practice, thereby increasing target activation to provide sufficient statistics for producing images of the desired quality.

[0093] List of reference symbols used Treatment device 100 Treatment table (patient treatment bed) 101 Position marker 106 Robotic Arm 102 Particle radiation device 103 Accelerator 112 Rack 105 Magnet 109 Radiation emission head 104 Beam monitor 110 Particle Beam 111 Beam transport system 107 Treatment Planning System 108 Quality Assurance System for Radiation Therapy2 Detector device 3 Support mechanism 7 Base 12 Support arm 14 Pivot connector 16 Pivoting base 17 Sliding connector 19 track Detection module support structure 18 Detection module 8 Computing System 4 Attenuation point 113 Rising edge 114 Detector transport device 5 Cart 9 Guardrail 23 Height adjustment mechanism 25 Wheel 27 Cabinet 34 Adapter interface 20 Base positioning element 32 Treatment table fixing element 35 Phantom equipment 6 Main body 22 PMMA material,… Cavity 24 Hole 26 Slot 28 Transverse groove 28a Axial groove 28 b Top surface 30 Side 31 Chamfered, rounded corners 33 Axial center axis A Frame rotation axis B

Claims

1. A quality assurance system for radiation therapy (2) used in a treatment apparatus (100), the treatment apparatus (100) comprising a treatment table (101) and a particle radiation device (103) having a radiation emitting head (104) for particle beam radiation, the quality assurance system comprising - a detector arrangement (3) comprising at least one detection module (8) configured to measure gamma radiation emitted by a target object subjected to a beam of particle radiation, and - a support mechanism (7) on which the at least one detection module (8) is mounted, the support mechanism (7) comprising a base (12) configured to be removably coupled to a treatment table (101) of the treatment device (100), and at least one detection module support structure (18) pivotally coupled to the base (12).

2. The system according to claim 1, wherein: The detection module support structure (18) has a substantially C-shape with an opening section configured for a particle radiation beam emitted by a radiation emitter (104) of the particle radiation device (103) to transmit through the opening section.

3. System according to the preceding claim, wherein The opening section has a width (Dgap) that is greater than a width of the treatment table (101).

4. The system according to claim 1, wherein: The detection module support structure (18) has at least two opening sections, and the at least two opening sections are configured to allow the particle radiation beam emitted by the radiation emitter (104) of the particle radiation device (103) to pass through the opening sections.

5. System according to the preceding claim, wherein At least one of the at least two opening sections has a width (Dgap) that is greater than a width of the treatment table (101).

6. A system according to any one of the preceding claims, wherein: The support mechanism (7) includes a support arm (14) that connects the detection module support structure (18) to the pivot connector (16) and positions the detection module support structure (18) relative to the pivot connector (16) so that a central axis of the detection module support structure is aligned with a rotational axis of the pivot connector.

7. A system according to any one of the preceding claims, wherein: The pivot coupling (16) includes a motor configured to motorize the detection module about a rotation axis (A) of the pivot coupling (16).

8. A system according to any one of the preceding claims, wherein The support mechanism (7) of the detector device (3) further comprises a sliding coupling (19) configured for translation of at least the detection module support structure (18), for example comprising a track on the base (12) engaging a complementary track or channel on the pivoting base (17).

9. A system according to any of the preceding claims, further comprising a detector transport device (5), the detector transport device (5) comprising a cart (9) having a support surface for removably mounting the detector device thereon, the cart (9) having ground engaging members, for example in the form of wheels (27) or rollers, allowing the cart to be moved to and away from a treatment device, the treatment device being configured for positioning the detector device (3) for coupling thereto.

10. The system according to the preceding claim, wherein The trolley (9) of the detector transport device comprises a position adjustment mechanism (25) for moving the detector device on the support surface of the trolley (9) or moving the detector device away from the support surface of the trolley (9).

11. System according to any of the two preceding claims, wherein The cart includes guardrails (23) that receive ends of the detection module support structure (18) therein to protect the detection module when the detector device (3) is installed and loaded on the detector transport device (5).

12. The system according to any of the three preceding claims, further comprising a lifting mechanism for transferring the detector device (3) from the trolley (9) to the treatment table (101).

13. The system according to any of the preceding claims, further comprising an adapter interface (20) mountable on a treatment table (101) of a treatment device (100), the detector device (3) being mountable on the adapter interface (20) for coupling to the treatment table (101).

14. The system according to the preceding claim in combination with any one of claims 9 to 12, wherein The adapter interface (20) and the trolley (9) have mutually engaging fixing elements for storing the adapter interface (20) on the trolley when the trolley is not in use.

15. The system according to any of the preceding claims, further comprising a phantom device (6), the phantom device comprising a body (22) and one or more cavities (24) formed in the body, the body comprising or consisting of one or more materials selected from the group consisting of polyethylene (PE), HE solid water, virtual water, RW1, RW3, polystyrene, blue water or polymethyl methacrylate (PMMA), or other low Z materials having a typically short-lived radioactive isotope produced by the beam, or having a radioactive isotope having a short life span in a radioactive environment such as 18 O. 63 Cu or 68 The isotope with a high probability of emitting a positron after interacting with the Zn radiation beam (111).

16. System according to the preceding claim, wherein The cavity of the phantom device comprises holes (26) and / or slots (28) formed in the material of the body, the slots may comprise transverse slots (28a) and axial slots (28b).

17. System according to any of the two preceding claims, wherein The phantom device comprises a substantially flat front surface (30) and side surfaces (31) substantially orthogonal to the top or front surface and connected to the top or front surface via chamfered or rounded corner surfaces (33).

18. System according to the preceding claim, wherein The side surface (31) is substantially cylindrical or polygonal.

19. The system according to any of the preceding claims, further comprising a computing system (4) connectable to the detector device (3) for acquiring measurement data from the detection modules (8) and for controlling the detector device.

20. A system according to any one of the preceding claims, wherein The computing system (4) outputs at least one distal decay coordinate of the measured activation, the distal decay coordinate corresponding to a falling edge of the measured activation along the beam axis.

21. The system according to any of the preceding claims, wherein the computing system (4) outputs the coordinates of at least one rising edge of the measured activation, the rising edge coordinates corresponding to the entry point of the illuminated target.

22. A treatment apparatus (100) in combination with a quality assurance system for radiation therapy according to any one of the preceding claims, wherein In use, the detector device (3) is mounted on a treatment table (101) of the treatment device, and a radiation emission head (104) of the treatment device is positioned for transmitting a particle radiation beam through an opening in the detection module support structure (18), the position of the detection module support structure being adjusted for alignment with the radiation emission head (104) through the opening in the support structure (18).

23. A combination according to the preceding claim, wherein The detection module support structure is dynamically coupled to the base (12) and is configured to rotate in synchronization with the radiation emitting head (104) of the treatment device (100).

24. A combination according to any one of the two preceding claims, wherein The computing system (4) of the quality assurance system (2) for radiation therapy is connected to at least one of a treatment planning system module and a beam delivery system of the treatment apparatus (100) for receiving information about the target, the treatment plan, the irradiation progress and a log file from the irradiation course.

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