JP2009172262A - Particle beam irradiation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure an irradiation field made by charged particle beams precisely even when a patient is irradiated with charged particle beams from any direction by using a patient couch having a rotating gantry and a plurality of degrees of freedom. <P>SOLUTION: The charged particle beam irradiation system is provided with: a charged particle beam generator 101 for generating charged particle beams; an irradiation apparatus 104 for emitting charged particle beams to an object to be irradiated; a couch 106 for holding the object to be irradiated; and a γ rays detector for detecting a prompt γ rays generated by the object to be irradiated. The couch 106 is provided with the γ rays detector. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a particle beam irradiation system, and more particularly to a charged particle beam irradiation system that irradiates an affected area such as a tumor with a charged particle beam.

  A method for treating cancer by irradiating a cancer patient with a charged particle beam such as a proton beam is known. The system used for treatment includes a charged particle beam generator, a beam transport system, and a treatment room. The charged particle beam accelerated by the charged particle beam generation device reaches the irradiation device in the treatment room through the beam transport system, and the distribution is expanded by the irradiation device, so that the irradiation field of the charged particle beam suitable for the shape of the affected part in the patient's body. Form. At that time, as means for confirming that the irradiation field is formed at a desired position, as in Patent Document 1, positron emission tomography (PET) is used after gamma rays from positron emitting nuclides generated in the irradiation field. The method of shooting is used.

  Similarly, a method for confirming an irradiation field by observing gamma rays (prompt gamma rays) generated from excited carbon, oxygen, and nitrogen nuclei generated in the irradiation field has been proposed (Non-Patent Document 1).

JP-A-9-189769 APPLYED PHYSICS LETTER 89, 183517 (2006) “Prompt gamma measurements for locating the dose falloff region in the proton therapy”

  In the conventional radiation field measurement method using PET in the particle beam therapy system, it is necessary to move the patient from the treatment room to the PET examination room where gamma ray measurement is performed after the radiation treatment. It was a burden. In addition, since there is a time difference between treatment and gamma ray measurement, the generated positron emitting nuclide has moved to a position different from the irradiation field due to physiological phenomena, making it difficult to confirm the irradiation field with high accuracy. In particular, in the case of proton beam therapy, the proton that reaches the deepest position in the irradiation field does not have sufficient energy to cause a nuclear reaction that generates a positron-emitting nuclide, and so on. It has been difficult to accurately measure the vicinity of the deepest irradiation field in the patient's body relative to the direction (hereinafter abbreviated as the end of the range of charged particles).

  When confirming an irradiation field using prompt gamma rays, it is necessary to bring the gamma ray detector as close as possible to the affected part of the patient in order to confirm the irradiation field with higher accuracy. Furthermore, in order to accurately measure the vicinity of the end of the range of the charged particle beam, the charged particle beam incident axis (hereinafter abbreviated as the beam axis) at the end of the range calculated before the patient treatment by the treatment planning system with respect to the irradiation field forming apparatus. It is preferable to install the gamma ray detector so that the straight line connecting the projection point above and the center of the gamma ray sensitive surface of the gamma ray detector is perpendicular to the beam axis. Therefore, when using a rotating gantry and a patient couch with multiple degrees of freedom to irradiate a patient with charged particle beams from various directions, a means to reposition the gamma ray detector is required. No method has been invented. An object of the present invention is to use a rotating gantry and a patient couch having a plurality of degrees of freedom to irradiate a patient with a charged particle beam from any direction. It is to provide an irradiation system.

  A feature of the present invention that achieves the above-described object is that a particle beam generating apparatus that generates particle beams, an irradiation apparatus that emits particle beams to an irradiation target, a couch that holds the irradiation target, and prompt gamma rays generated from the irradiation target And a gamma ray detector on the couch.

  According to the present invention, when a patient is irradiated with a charged particle beam, the irradiation field formed by the charged particle beam can be measured with high accuracy.

  Hereinafter, a particle beam irradiation system which is a preferred embodiment of the present invention will be described.

  In the present embodiment, a proton beam therapy apparatus that is a kind of particle beam therapy system will be described as an example with reference to FIG. The proton beam treatment apparatus includes a proton beam generation apparatus 101, a beam transport apparatus 102, and a rotary irradiation apparatus 103. The rotary irradiation device 103 includes a rotating gantry (not shown) and an irradiation field forming device (hereinafter abbreviated as an irradiation nozzle) 104. The irradiation nozzle 104 is installed in the rotating gantry and rotates with the rotation of the rotating gantry. The proton beam generator 101 includes an ion source (not shown), a pre-stage accelerator (for example, a linear accelerator) 101a, and a synchrotron 101b. Proton ions generated in the ion source are accelerated by the pre-accelerator 101a. The proton beam emitted from the front stage accelerator 101a is accelerated to a predetermined energy by the synchrotron 101b, and then emitted from the emission deflector 102a to the beam path 102b of the beam transport device 102. This proton beam is guided to the rotary irradiation apparatus 103 through the beam path 102 b and irradiated to the cancer affected part of the subject 105 (patient to be irradiated) lying on the patient couch 106. A portion of the beam path 102 is attached to the rotating gantry. In this embodiment, a proton beam therapy apparatus is used as an example, but the same effect can be obtained for other particle beam therapy systems using heavy particle beams or the like. Furthermore, in this embodiment, the synchrotron is used as the accelerator to which the proton beam generator 101 is attached, but the same effect can be obtained with other charged particle beam accelerators such as a cyclotron and a linac.

  Next, the function of the patient couch 106 will be described with reference to FIG. The patient couch 106 includes a bed 106a on which a patient lies during treatment and a movable unit group for aligning the bed 106a at various positions and angles. The movable parts having different degrees of freedom move precisely using a high-precision stepping motor (not shown), so that the position of the affected part of the patient lying on the bed 106a is the most suitable position for proton beam irradiation.・ It is fixed at an angle with respect to the proton beam irradiation direction.

  Similarly, the function of each movable part group of the patient couch 106 will be described with reference to FIG. The movable portion 106b of the patient couch 106 installed on the bed 106a on which the patient lies during the proton beam treatment is similarly shaft 107a with respect to the fixed portion 108 installed on the opposite side of the bed 106a with respect to the movable portion 106b. The couch 106a can be rotated and fixed to an arbitrary angle with respect to the shaft 107a by using a motor. The movable portion 106c has a degree of freedom to rotate around the shaft 107b with respect to the movable portion 106d installed adjacently, and the bed 106a is rotated and fixed to an arbitrary angle around the shaft 107b using a motor. Can be made. The movable portion 106d has a degree of freedom that allows the fixed portion 108 to rotate about the shaft 107c, and can tilt the bed 106a to an optimum angle with respect to the plane formed by the shaft 107a and the shaft 107c using a motor. The movable portion 106e has a degree of freedom to move horizontally in parallel with the shaft 107a with respect to the movable portion 106f installed adjacent to the movable portion 106e, and can horizontally move the bed 106a in parallel with the shaft 107a using a motor. . The movable portion 106f has a mechanism that can expand and contract in parallel with the shaft 107b, and can move the bed 106a vertically in parallel to the shaft 107b using a motor. The movable portion 106g has a mechanism for horizontally moving the entire patient couch 106 in parallel with the shaft 107c, and the bed 106a can be horizontally moved in parallel with the shaft 107c using a motor.

  When driving each movable part and aligning the bed 106a attached to the patient couch 106 at the optimum position and angle, a treatment planning system (not shown) and a patient positioning control system (not shown) are used. The operator confirms the proton beam irradiation field calculated by the treatment planning system so that the charged particle beam irradiation field suitable for the shape of the affected part can be sufficiently formed in the patient's body, while positioning the patient couch 106. Alignment information such as the position and angle of the patient couch 106 is set in the treatment plan. At this time, irradiation parameter information such as the rotation angle information of the rotating gantry and the patient bolus shape is also set in the treatment plan.

  The set alignment information of the patient couch 106 is passed from the treatment planning system to the patient positioning control system through a communication device such as a cable. According to the information obtained from the treatment plan, the patient positioning control system sends a prescribed current to each stepping motor that is a driving force of each movable part of the patient couch 106, and the alignment of the patient couch 106 defined in the treatment plan is achieved. As described above, each movable part is moved to a prescribed position / angle.

  Furthermore, a diseased part perspective image of the patient lying on the patient couch 106 is taken by a positioning image acquisition device (not shown) attached in the treatment room. The obtained fluoroscopic image information is passed to the patient positioning control system. Based on the fluoroscopic image information, the patient positioning control system performs fine adjustment of the patient couch 106 alignment again so that the affected area of the patient accurately matches the irradiation position of the proton beam set in the treatment plan.

  Next, the principle of confirming a proton beam irradiation field in a treated patient body with a gamma ray detector will be described. When a high-energy particle beam (in this embodiment, a proton beam) is incident on the material, the proton beam excites the nuclei in the material and generates various radionuclides that cause gamma decay on the proton beam irradiation field. The generated radionuclide decays with a half-life determined for each nuclide, and emits high-energy gamma rays such as several MeV (1 MeV to 10 MeV). This gamma ray is called prompt gamma ray. Prompt gamma rays emitted from radionuclides immediately pass through the outside of the material. Therefore, a gamma ray detector installed outside the substance detects prompt gamma rays that have passed through the substance, and based on the detection data output from the gamma ray detector, the irradiation field confirmation system (not shown) By estimating the position inside, the irradiation field of the proton beam in the substance can be measured. In other words, a gamma ray detector is used to detect prompt gamma rays generated from the body of the patient during proton therapy, and the irradiation field confirmation system based on the detected data detects the gamma ray energy, the incident position / angle at the gamma ray detector, and the counting. When the rate is measured, it is possible to confirm the irradiation field in the patient who has undergone proton therapy. Since the energy emitted from the excited nucleus is 1 MeV to 10 MeV, the irradiation field confirmation system determines that the gamma ray energy of the detection data is 1 MeV to 10 MeV as valid data, and determines the irradiation field. You may check.

  A gamma ray detector that can measure gamma rays with high energy of several hundred keV to several tens MeV is particularly suitable. In this embodiment, a Compton camera that can detect high energy gamma rays by using Compton scattering of gamma rays and can measure the incident position / angle and energy of gamma rays on the detector sensitive surface is detected by gamma ray detection. Use as a container. However, the present invention can be applied to radiation detectors other than Compton cameras as long as high-energy gamma rays can be measured.

  Next, the characteristic system of the present embodiment will be specifically described. As shown in FIG. 3, a gamma ray detector installation device (detector fixing device) 203 is installed on a patient couch 201 on which a patient lies during proton beam treatment. FIG. 3A is a view of the gamma ray detector installation device 203 as viewed from the bed 201a side of the patient couch 201, and FIG. 3B is a view of the gamma ray detector installation device 203 from the opposite side. . A gamma ray detector 202 is attached to the tip of the gamma ray detector installation tool 203. As described above, the gamma ray detector 202 needs to be as close as possible to the prompt gamma ray source, i.e., the patient, in order to confirm the irradiation field in the patient's body that is produced with higher accuracy.

  Further, as shown in FIG. 8, in order to accurately measure the vicinity of the proton beam end range in particular, the projection point 804 on the beam axis 803 at the end range calculated by the treatment planning system, and a gamma ray detector 801 are used. The gamma ray detector 801 needs to be installed so that the straight line 802 connecting the sensitive surface center 801b in the gamma ray sensitive surface 801a is perpendicular to the beam axis 803.

  Considering the above, the gamma ray detector installation instrument 203 of FIG. 3 includes movable parts 203a, 203b, 203c, 203d, 203e, 203f, and 203g. The movable portion 203a attached to the gamma ray detector 202 has a degree of freedom to rotate around the shaft 204a, and freely uses the driving force (not shown) such as a stepping motor to center around the shaft 204a. The gamma ray detector 202 can be rotated to an arbitrary angle. The movable portion 203b has a degree of freedom to rotate around the shaft 204b, and the gamma ray detector 202 can be freely rotated to any angle around the shaft 204b using power. When the movable unit 203b finely adjusts the orientation and angle of the gamma ray detector 202 with respect to the patient lying on the bed 201a, compared to the function of the movable unit 203d (described later) having a similar degree of freedom with respect to the gamma ray detector 202. Used for. The movable portion 203c has a mechanism and power that can be expanded and contracted horizontally along the shaft 204c, and can move the gamma ray detector 202 horizontally along the shaft 204c. The movable portion 203d has a degree of freedom to rotate around the shaft 204d, and can freely rotate the gamma ray detector 202 to an arbitrary angle around the shaft 204d using power. The movable portion 203d is used when the gamma ray detector 202 is rotated at a large angle as compared with the function of the movable portion 203b (described above) having a similar degree of freedom with respect to the gamma ray detector 202. The movable portion 203e has a mechanism and power that can horizontally expand and contract along the direction of the axis 204e, and can move the gamma ray detector 202 up and down perpendicular to the ground. The gamma ray detector 202 can be moved away from or closer to the patient lying on the bed 201a by the operation of the movable portion 203e. The movable portion 203f has a degree of freedom to rotate around the shaft 204e, and the gamma ray detector 202 can be freely rotated to an arbitrary angle around the shaft 204e using power. The movable part 203g is attached to the movable part 201b of the patient couch that rotates the bed 201a around the axis 204g. The movable portion 203g has a degree of freedom to rotate around the shaft 204g, and the gamma ray detector 202 can be freely rotated to any angle around the shaft 204g using power.

  Even when the rotating gantry, the irradiation nozzle 104, and the patient couch 201 are operated for the treatment of the patient by the action of the movable parts of the gamma ray detector installation device 203, the irradiation field of the proton beam without interfering with the treatment. The gamma ray detector 202 can be installed at a position where the vicinity of the range end can be detected with higher accuracy.

  Next, a control system for driving each movable part of the gamma ray detector installation instrument 203 by a predetermined amount and arranging the gamma ray detector 202 at an optimal position will be described with reference to FIG. In order to form a proton beam irradiation field optimal for the shape of the affected part in the patient's body, the operator uses the treatment planning system 110 to rotate the gantry information (rotation angle information) 111a and the patient couch information as the basis for positioning the patient couch 201 ( When the alignment information) 111b and the irradiation parameter information 111c are determined, the proton beam irradiation field is calculated as described above, and the calculated irradiation field information 111d is obtained.

  When the preparation for treatment is started, a patient bolus or the like having a shape optimal for treatment produced by receiving the irradiation parameter information 111c is installed in the irradiation nozzle. Further, the irradiation control system receives irradiation parameter information 111c from the treatment planning system 110, such as setting of the scatterer thickness for diffusing the proton beam, setting of the operating pattern of the accelerator, and setting of the excitation pattern of the scanning electromagnet in the irradiation nozzle. 112c. The rotating gantry information 111a is passed from the treatment planning system 110 to the rotating gantry control system 112a, and the rotating gantry is rotated according to the rotating gantry control system 112a so as to have a specified rotation angle determined by the treatment planning system 110. As described above, the alignment information 111e that is the basis for positioning the patient couch 201 is passed to the patient positioning control system (couch control system) 112b, and each movable part motor of the patient couch 201 is controlled according to the control of the patient positioning control system 112b. The patient couch 201 is aligned so that the bed on which the patient lies is placed at a prescribed position and angle determined by the treatment planning system 110.

  Next, in order to perform the positioning of the patient couch 201 in more detail, a fluoroscopic image of the affected part of the patient is taken by the positioning image acquisition device 117a attached in the treatment room. At this time, the operator detects the gamma ray at a position that does not interfere with the fluoroscopic imaging of the affected part of the patient image of the positioning image acquisition device 117a by using the detector installation instrument control system 115 that controls the driving of each movable part of the detector installation instrument. The gamma ray detector installation tool 203 is aligned so that the instrument 202 is installed.

  When a fluoroscopic image of the affected part of the patient is taken, the obtained fluoroscopic image information 117b is transferred to the patient positioning control system 112b. The patient positioning control system 112b finely adjusts the alignment of the patient couch 201 so that the affected area of the patient accurately matches the irradiation position of the proton beam calculated by the treatment planning system 110 based on the fluoroscopic image information 117b.

  When the alignment adjustment of the patient couch 201 is completed, the final patient couch information 111b of the patient couch 201 is passed from the patient positioning control system 112b to the arithmetic processing unit 113 in the detector installation instrument control system 115. At this time, the rotation gantry information 111a and the information of the calculated irradiation field information 111d by the treatment planning system 110 are also passed from the treatment planning system 110 to the arithmetic processing unit 113.

  The arithmetic processing unit 113 uses the three information of the rotating gantry information 111a, the patient couch information 111b of the patient couch, and the calculated irradiation field information 111d to calculate the beam axis at the end of the proton beam range calculated in advance by the treatment planning system 110. The position where the gamma ray detector 202 is installed so that the straight line connecting the projection point above and the center of the gamma ray sensitive surface of the gamma ray detector 202 is perpendicular to the beam axis, and the gamma ray detector 202 can be as close to the patient as possible. That is, the three-dimensional position of the gamma ray detector 202 on the patient couch 201 that can measure the vicinity of the end of the proton beam range with higher accuracy as described above is calculated. Further, the arithmetic processing unit 113 uses the degree of freedom of each movable part of the gamma ray detector installation tool 203 to determine the prescribed drive amount information (movable) for each movable part that allows the gamma ray detector 202 to be installed at the aforementioned three-dimensional position. (Quantity information) 114 is calculated.

  The detector installation instrument control system 115 operates each movable part drive mechanism 116 of the gamma ray detector installation instrument 203 according to the prescribed drive amount information 114 for each movable part calculated by the arithmetic processing unit 113, and the gamma ray detector installation instrument. 203 is aligned. Using such control, alignment of the gamma ray detector 202 is performed.

  Further, using the detector installation instrument control system 115 or the treatment planning system 110, the specified drive amount information 114 of the movable part drive mechanism 116 is directly input for each movable part, and the gamma ray detector installation instrument 203 is manually aligned. Can do.

  Further, the specified drive amount information 114 is held in a recording medium (not shown) provided in the detector installation instrument control system 115, unless the format of the recording medium and the data recorded on the recording medium are erased. The movable part can be re-aligned by selecting the plurality of prescribed movable amount information 114 held on the recording medium any number of times. Erasing and selecting the prescribed movable amount information 114 data recorded on the recording medium is performed on the detector installation instrument control system 115 or from the treatment planning system 110.

  As a means for installing the gamma ray detector on the patient couch, a configuration as shown in FIG. 5 is also conceivable. The gamma ray detector installation tool (detector fixing device) 303 in FIG. 5 has a structure surrounding the patient couch 301. In the gamma ray detector installation tool 303, two semi-annular rails 303b along the circumference of a circle with a certain radius are installed on a bifurcated rail attachment 303c. The rail attachment 303c is provided with power to move the two attached rails 303b in conjunction with each other and rotate each rail 303b in a direction perpendicular to the patient couch 301, that is, in the circumferential direction of the rail 303b. You can make it. A detector jig 303a is attached to the tip of the rail 303b so as to be sandwiched between the two rails 303b. The detector jig 303a can be detached from the rail 303b and can be installed at any other position on the rail 303b. A gamma ray detector 302 is installed on the detector jig 303a with the gamma ray sensitive surface facing the patient. The detector jig 303a is provided with a power mechanism that moves the gamma ray detector 302 up and down within a range perpendicular to the circumferential direction of the rail 303b, and moves the gamma ray detector 302 closer to or away from the patient. can do. The rail attachment tool 303c is connected to the movable part 303d. The movable portion 303d has a degree of freedom to rotate in the vertical direction with respect to the patient couch 301, and the rail 303b can be inclined at an arbitrary angle with respect to the patient couch 301 using power. The movable part 303e, which is a contact point between the patient couch 301 and the gamma ray detector installation tool 303, has a degree of freedom to rotate in the horizontal direction with respect to the patient couch 301. The gamma ray detector installation tool 303 can be rotated. Furthermore, the movable part 303e has a degree of freedom that allows the patient couch 301 to move horizontally with respect to the direction in which the patient lies. By using power, the patient couch moves the gamma ray detector installation tool 303 horizontally relative to the patient couch 301. be able to. By the action of each movable part of these gamma ray detector installation tools 303, even when the rotating gantry, the irradiation nozzle 104, and the patient couch 301 are moved for the treatment of the patient, the proton beam irradiation field is not disturbed. The gamma ray detector 302 can be installed at a position where the vicinity of the maximum reachable depth of the proton beam can be detected with better accuracy.

  The gamma ray detectors attached to the patient couch via the detector installation device can be used not only as a single unit but also as a plurality of attachments on the detector installation device. FIG. 6A shows a configuration diagram in which a plurality of gamma ray detectors are installed on the patient couch described in FIG. A plurality of gamma ray detectors 402b are arranged on the circumference of a certain radius so as to be connected to both sides of the gamma ray detector 402a attached to the movable portion 403a of the gamma ray detector installation device (detector fixing device) 403. Has been. By arranging a plurality of gamma ray detectors 402a and 402b in a ring shape, the gamma ray detectors 402a and 402b can cover the periphery of the patient who is undergoing the proton beam treatment, so that the prompt gamma rays flying from the patient body can be efficiently and at once. It can be detected. The gamma ray detector installation instrument 403 is movable in the same manner as the gamma ray detector installation instrument 303 of FIG. 3, and the treatment is performed even when the rotating gantry, the irradiation nozzle 104, and the patient couch 401 are moved for patient treatment. The gamma-ray detectors 402a and 402b can be installed at positions where the proton beam irradiation field and the vicinity of the maximum reachable depth of the proton beam can be detected with better accuracy.

  Another example of installing a gamma ray detector on a patient couch will be described with reference to FIG. As shown in FIG. 6B, a large annular gamma ray detector 402c having a detector surface covering the patient couch is attached to the patient couch 401 via the gamma ray detector installation tool 403, thereby FIG. The same effect as when a plurality of gamma ray detectors 402 a and 402 b are attached to the patient couch 401 can be obtained. In this embodiment, the gamma ray detector 402c has an annular structure that covers the circumference of a circle with a certain radius. However, when the rotating gantry, the irradiation nozzle 104, and the patient couch 401 are moved for patient treatment, gamma ray detection is performed. As long as the devices 402a, 402b, and 402c are installed at the optimum positions for the confirmation of the above-mentioned proton beam field and can cover the patient, any gamma ray detectors 402a, 402b connection method and gamma ray detector The shape of 402c is also applicable.

  Next, FIG. 7A shows a configuration diagram in which a plurality of gamma ray detectors are installed on the patient couch described in FIG. As shown in FIG. 7A, a plurality of gamma ray detectors 502a are mounted on a rail 503b of a gamma ray detector installation device (detector fixing device) 503 with the gamma ray sensitive surface facing the patient couch 501. . Since the semi-annular rail 503b runs along the circumference of a circle with a certain radius, the plurality of attached gamma ray detectors 502a can detect prompt gamma rays flying from the patient's body at a time, as in FIG. It can be detected efficiently. The gamma ray detector installation device 503 is movable in the same manner as the gamma ray detector installation device 303 in FIG. 5, and even when the rotating gantry, the irradiation nozzle 104, and the patient couch 501 are moved for the treatment of the patient, the treatment is hindered. The gamma ray detector 502a can be installed at a position where the proton beam irradiation field and the vicinity of the maximum reachable depth of the proton beam can be detected with better accuracy. Further, as shown in FIG. 7B, a plurality of gamma ray detectors 502a are attached to the rail 503b by attaching an annular large gamma ray detector 502b to the rail 503b along the circumference of a circle with a certain radius. The same effect as in the case of 7 (a) can be obtained.

  In order to control the quality of the proton beam treatment system, it is necessary to confirm the irradiation field of the proton beam in the water phantom (not shown) outside the treatment time. The conventional confirmation method was to scan the pinpoint chamber (not shown) in the water phantom while irradiating the proton beam to the water phantom and measure the dose distribution inside the water phantom. In order to perform the measurement, it was necessary to scan the pinpoint chamber finely in the water phantom, which was very time consuming.

  The proton beam irradiation field in the water phantom installed on the patient couch can be confirmed by the same principle as the measurement of the proton beam range in the patient's body. In the method using the gamma ray detector, the prompt irradiation field can be estimated quickly by measuring the prompt gamma ray from the outside of the water phantom, and the ratio of quality control time in the proton beam treatment is calculated using the conventional pinpoint chamber. It is expected to be significantly shortened compared to dose distribution measurement.

  According to Embodiments 1 and 2, even when a patient is irradiated with charged particle beams from various directions using a rotating gantry or a patient couch having a plurality of degrees of freedom, the gamma ray detector is arranged near the patient. Furthermore, the straight line connecting the projected point on the beam axis at the end of the charged particle beam range calculated by the treatment plan before the patient treatment and the center of the gamma ray sensitive surface of the gamma ray detector is perpendicular to the beam axis. Thus, a gamma ray detector can be arranged. Therefore, even when a patient is irradiated with a charged particle beam from any direction using a rotating gantry and a patient couch having a plurality of degrees of freedom, the irradiation field formed by the charged particle beam can be accurately measured.

  Since Examples 1 and 2 can measure data for confirming the charged particle beam irradiation field in the patient body during the irradiation treatment with the charged particle beam, it is compared with the conventional irradiation field measurement method using PET. Thus, the treatment time can be reduced and the burden on the patient can be reduced.

  In Examples 1 and 2, a proton beam or a heavy particle beam (carbon beam or the like) can be used as a charged particle beam. Examples 1 and 2 in which prompt gamma rays are detected to measure the shape of the irradiation field are particularly effective in the case of a proton beam irradiation system using proton beams.

  In the first and second embodiments, prompt gamma rays emitted from the irradiation target can be detected and information necessary for measuring the shape of the irradiation field can be collected while the charged particle beam is being irradiated. The displacement due to physiological phenomena is small, and the shape of the irradiation field can be measured with high accuracy. In addition, the time for measuring the shape of the irradiation field can be shortened, and the throughput is improved.

It is a block diagram of the proton beam treatment system which is one preferable Example of this invention. It is a block diagram of the patient couch shown in FIG. It is a block diagram of the detector installation instrument attached to the patient couch shown in FIG. It is a block diagram of the drive control system of the detector installation instrument shown in FIG. It is a block diagram of the detector installation instrument attached to the patient couch shown in FIG. It is a block diagram of the detector installation instrument shown in FIG. It is a block diagram of the detector installation instrument shown in FIG. FIG. 4 is a configuration diagram of an optimum installation position in the gamma ray detector shown in FIG. 3.

Explanation of symbols

101 proton beam generator 101a front stage accelerator 101b synchrotron 102 beam transport device 102a exit deflector 102b beam path 103 rotary irradiation device 104 irradiation field forming device 105 patient 106, 201, 301 patient couch 106a, 201a bed 106b, 106c, 106d 106e, 106f, 106g, 203a, 203b, 203c, 203d, 203e, 203f, 203g, 303d, 303f, 403e Movable parts 107a, 107b, 107c, 204a, 204b, 204c, 204d, 204e, 204f Shaft 108 fixed part 110 Treatment planning system 111a Rotating gantry information 111b Patient couch information 111c Irradiation parameter information 111d Calculated irradiation field information 112a Rotating gantry control system 112b Person positioning control system 112c Irradiation control system 113 Arithmetic processor 114 Drive amount information 115 Detector installation instrument control system 116 Movable part drive mechanism 201b Patient couch movable part 202, 302, 402a, 402b, 502a, 801 Gamma ray detector 203 Gamma ray detection Device installation tool 301a Patient couch groove 303, 403, 503 Gamma ray detector installation device 303a Detector jig 303b, 503b Rail 303c Rail attachment tool 303e Detector installation device base 401, 501 Patient couch 402c Gamma ray detector 801a Gamma ray sensitive surface 801b Sensitive surface center 802 Straight line 803 Beam axis 804 Projection point on the beam axis at the end of the range calculated by the treatment planning system

Claims (5)

A particle beam generator for generating particle beams;
An irradiation device for emitting the particle beam to an irradiation target;
A couch for holding the irradiation object;
A gamma ray detector for detecting prompt gamma rays generated from the irradiation object,
The particle beam irradiation system, wherein the couch includes the gamma ray detector.   A system in which a gamma ray detector is installed at a position where the prompt gamma rays are detected even when the couch is irradiated with a charged particle beam from a plurality of angles with respect to an irradiation target by moving the rotating gantry or the couch; The particle beam irradiation system according to claim 1.   The particle beam irradiation system according to claim 1, wherein the couch includes two or more gamma ray detectors.   The particle beam irradiation system according to any one of claims 1 to 3, wherein the energy of the prompt gamma rays is 1 MeV to 10 MeV.   The particle beam irradiation system according to claim 1, wherein the particle beam is a proton beam.

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