JP5047083B2 - Particle beam therapy system - Google Patents

Description

  The present invention relates to a particle beam therapy system that emits a charged particle beam (ion beam) such as protons or carbon ions to an irradiation target.

As a method for treating cancer or the like, a method of irradiating an affected area of a patient with a charged particle beam (hereinafter referred to as a beam) of protons or carbon ions is known. The particle beam therapy system includes a charged particle beam generator, a beam transport device, and an irradiation field forming device (hereinafter referred to as an irradiation nozzle). The charged particle beam generator accelerates a beam that circulates along a circular orbit to a desired energy.
The beam accelerated to the target energy is transported to the irradiation device through the beam transport device and emitted from the irradiation device. The emitted ions are irradiated to the affected part of the patient in the treatment room.

  As a charged particle beam irradiation method in the particle beam therapy system, there are a scanning irradiation method and a scatterer irradiation method.

In the scanning irradiation method, the affected part is divided into a plurality of layers in the depth direction (beam traveling direction) from the body surface of the patient, and the beam is irradiated in each layer. In the case of the scanning irradiation method, a pair of scanning electromagnets for scanning a thin beam in the irradiation region is provided in the irradiation apparatus. By changing the beam energy, the beam irradiation layer (irradiation position in the beam traveling direction) is changed, and by changing the excitation amount of the scanning magnet, the irradiation position on the surface perpendicular to the beam traveling direction is changed. To do. In this way, the beam is scanned to create the necessary particle beam field for the patient. The scanning irradiation method does not require a device such as a bolus required for other irradiation methods, and therefore has an advantage that the number of devices to be arranged on the beam path in the irradiation apparatus can be reduced. In the scanning irradiation method, it is necessary to improve the accuracy of the irradiation position of the beam.
For example, when air exists in the irradiation device, the beam is scattered by the air, so that the beam spreads and a high dose is given to normal tissues other than the affected part. In Patent Document 1, in order to reduce scattering of the beam by air, a gas chamber filled with a gas having a small particle scattering such as He gas is installed on the beam axis in the irradiation nozzle. In such a configuration, the gas chamber occupies most of the beam path inside the irradiation nozzle that performs the scanning irradiation method.

  In the case of the scatterer irradiation method, devices such as a scatterer, an enlarged Bragg peak forming filter, a collimator, and a bolus are installed in the irradiation apparatus. Using these devices, the energy distribution and beam shape of the beam are shaped to form a particle beam irradiation field suitable for the shape of the affected area. The scatterer irradiation method can generally achieve a higher dose rate than the scanning irradiation method. Further, in the scatterer irradiation method, since it is not necessary to suppress the scattering of the beam by air, it is not necessary to mount a gas chamber in the irradiation apparatus unlike the scanning irradiation method. The scatterer irradiation method includes a wobbler irradiation method, a double scatterer irradiation method, and the like.

  As described above, since the configuration in the irradiation apparatus is different between the scanning irradiation method and the scatterer irradiation method, it is difficult to realize a plurality of irradiation methods with one particle beam irradiation system. In Patent Document 2, a plurality of treatment rooms are provided, a scanning type irradiation device is installed in some treatment rooms, and a scatterer type irradiation device is set in another treatment room to realize a plurality of irradiation methods. Yes. However, the particle beam therapy system becomes larger and the cost of the entire system increases.

JP 2007-229025 A JP 2007-268031 A

  In the scanning irradiation method, a dose distribution matching the shape of the affected part can be formed by scanning a thin beam using an electromagnet installed in the irradiation nozzle. Also, the scanning irradiation method does not require a device such as a bolus normally prepared for each patient. However, due to the feature of scanning a thin beam so as to trace the affected area, the irradiation time becomes longer for a large affected area. Therefore, for a large affected area, an irradiation method for forming a beam irradiation field using a scatterer, an enlarged Bragg peak forming filter, a collimator, a bolus, or the like is more appropriate. Thus, the effective irradiation method differs depending on the size of the affected area. Therefore, in order to always perform the beam irradiation efficiently, it is necessary to switch the irradiation method for each patient in the particle beam therapy system. As described above, when a certain irradiation nozzle performs the scanning irradiation method, most of the beam path inside the irradiation nozzle needs to be occupied by the gas chamber. It is difficult to install equipment. Therefore, it is difficult to share two different irradiation methods with one irradiation nozzle and easily switch between them.

  An object of the present invention is to provide a particle beam therapy system capable of realizing a plurality of irradiation methods with one irradiation nozzle.

  A feature of the present invention that achieves the above-described object is that a beam generation device that accelerates a charged particle beam to a set energy, an irradiation field forming device that is disposed in a treatment room and forms an irradiation field of the charged particle beam, and a beam A beam transport device that transports the charged particle beam emitted from the generator to the irradiation field forming device, and the irradiation field forming device includes an electromagnet that scans the charged particle beam incident on the irradiation field forming device, and a gas chamber. A first irradiation unit having a second irradiation unit having a scatterer for adjusting the amount of scattering of the charged particle beam, and the second irradiation unit or the inside thereof is made of an inert gas on the beam axis in the irradiation field forming apparatus. The object is to provide a control device that performs switching control so that any one of the first irradiation units having the filled gas chamber is disposed.

  According to the present invention, since a plurality of irradiation methods can be realized with one irradiation nozzle, the particle beam therapy system can be miniaturized.

  Hereinafter, a particle beam therapy system according to an embodiment of the present invention will be described with reference to the drawings.

In this embodiment, a proton beam therapy apparatus 100 that is one type of particle beam therapy apparatus will be described as an example with reference to FIG. The proton therapy apparatus 100 includes a proton beam (hereinafter referred to as a beam) generator 25, a beam transport device 22, and a rotary irradiation device 20. The beam generator 25 includes an ion source (not shown), a pre-accelerator (for example, a linear accelerator) 26 and a synchrotron 24.
The irradiation device 20 includes a rotating gantry (not shown) and an irradiation field forming device (hereinafter referred to as irradiation nozzle) 18. The irradiation nozzle 18 is installed in the rotating gantry and rotates with the rotation of the rotating gantry. The irradiation nozzle 18 is disposed in the treatment room and forms a beam irradiation field. The beam transport device 22 transports the beam generated by the beam generation device 25 to the irradiation device 20. Although the proton beam therapy apparatus is employed in this embodiment, the same effect can be obtained when a heavy particle beam therapy apparatus using carbon ions or the like is used.

  Proton ions generated in the ion source are accelerated by the pre-accelerator 26. The beam emitted from the front stage accelerator 26 is accelerated to a predetermined energy by the synchrotron 24 and then emitted from the emission deflector 23 to the beam path 21 of the beam transport device 22. This beam is guided to the rotary irradiation device 20 through the beam path 21 and is emitted from the irradiation device 20. The emitted beam is irradiated to the affected part (for example, cancer or tumor) of the patient 15 lying on the bed 16 in the treatment room. A part of the beam path 21 is attached to the rotating gantry. In this embodiment, the synchrotron is used as an accelerator for accelerating proton ions, but the same effect can be obtained when a cyclotron is used. Further, in this embodiment, the rotary irradiation device 20 is adopted, but the same effect can be obtained even with a fixed irradiation device.

  The configuration of the irradiation nozzle 18 will be described. As shown in FIG. 2, the irradiation nozzle 18 includes the scanning electromagnets 2a and 2b, the first gas chamber 1a, the first irradiation unit 17a, the second irradiation unit 17b, the collimator 5, the beam monitors 4a and 4b, the snout 6, and the patient bolus. 7 The irradiation nozzle 18 of the present embodiment includes a plurality of irradiation units (first irradiation unit 17a and second irradiation unit 17b). According to the present embodiment, a plurality of irradiation methods can be realized by the irradiation device 20 installed in one treatment room. The first irradiation unit 17a is used for an irradiation method that requires a gas chamber filled with an inert gas (He gas or the like), and the second irradiation unit 17b is used for an irradiation method that does not require a gas chamber. Here, the irradiation unit used for the scanning irradiation method in the first irradiation unit 17a and the irradiation unit used for the scatterer irradiation method in the second irradiation unit 17b will be described as an example.

The beam that has passed through the vacuum beam duct 8 and the vacuum blocking window 9 is incident on the irradiation nozzle 18. The first gas chamber 1a has a gas chamber shielding window 3a at the end on the upstream side (beam entrance side) in the beam traveling direction, thereby keeping the inside of the first gas chamber 1a airtight. The scanning electromagnets 2a and 2b have a configuration in which a coil is wound around an iron core, and is installed surrounding the first gas chamber 1a. The scanning electromagnet 2a is installed on the upstream side (hereinafter, upstream) in the beam traveling direction, and the scanning electromagnet 2b is installed on the downstream side (hereinafter, downstream) in the beam traveling direction. The scanning electromagnet 2a scans the beam 10 in the X direction, and the scanning electromagnet 2b scans the beam 10 in the Y direction.
That is, the pair of scanning electromagnets 2a and 2b scan the beam in a plane (affected area) perpendicular to the beam traveling direction. Here, the X direction refers to one direction on a plane orthogonal to the traveling direction of the beam. The Y direction refers to a direction orthogonal to the X direction on the plane.

The 1st irradiation part 17a has the 2nd gas chamber 1b. The first gas chamber 1a and the second gas chamber 1b are coupled by screwing the opposing flanges.
The second gas chamber 1b is installed on the downstream side of the first gas chamber 1a. A space is formed inside the gas chamber 1 constituted by the first gas chamber 1a and the second gas chamber 1b. An isolation window 3b is attached to an end on the downstream side (beam exit side) of the second gas chamber 1b, and isolates the space in the gas chamber 1 from the region outside thereof. The second gas chamber 1b has a configuration (movable member) that can expand and contract in the beam traveling direction, and the first gas chamber 1a has a fixed configuration (non-movable member). When the second gas chamber 1b expands and contracts in the horizontal direction with respect to the beam path, the overall length of the gas chamber 1 changes. That is, the occupation ratio of the gas chamber 1 in the beam path of the irradiation nozzle 18 can be changed.

  The second irradiation unit 17b includes a rotating body 11a, a rotating shaft part 11b, a scatterer 12, an enlarged Bragg peak forming filter (SOBP (Spread Out Bragg Peak) filter) 13, and a range shifter 14. The rotating body 11a, the scatterer 12, the SOBP filter 13, and the range shifter 14 are arranged in this order from the upstream side, and each is installed on the rotating shaft portion 11b. The scatterer 12 controls the amount of scattering of the beam. The SOBP filter 13 has a function of expanding a sharp Bragg peak generated by a single energy particle beam with respect to a dose distribution in the depth direction in accordance with the shape of the affected part. The SOBP filter 13 has a staircase structure made to have a different thickness on the surface through which the beam passes vertically. By passing the beam through each stage of the SOBP filter 13 with an appropriate distribution, an energy distribution with an appropriate distribution is given to the beam that was single energy before passing through the SOBP filter 13. In this embodiment, a ridge filter is employed as the SOBP filter 13, but the same effect can be obtained when a range modulation wheel is used. The collimator 5 limits the irradiation range of the beam in a plane perpendicular to the beam traveling direction according to the shape of the affected part. The bolus 7 adjusts the arrival depth of the beam so as to match the shape of the affected part in the beam traveling direction (depth direction of the affected part). Although not shown, the second irradiating unit 17b includes a plurality of scatterers 12, a SOBP filter 13, and a range shifter 14, and can rotate independently with respect to the rotating shaft unit 11b. . The second irradiation unit 17b is a movable structure fixing jig. The arrangement and type of devices stored in the second irradiation unit 17b can be changed by the scatterer irradiation method employed.

  The beam monitor 4a is disposed upstream of the first gas chamber 1a. The beam monitor 4b is disposed downstream of the second gas chamber 1b. These monitors can be installed in an arbitrary number and an arbitrary position to the extent that they do not interfere with other structures according to beam information necessary during beam irradiation. Examples of the beam monitor include a beam dose monitor that measures the dose of a beam, a beam position monitor that measures the position of a passing beam, and the like.

  A filling gas system for supplying He gas, which is an inert gas, into the gas chamber 1 will be described with reference to FIG. This filling gas system has a gas supply pipe 27, a flow rate adjusting valve 28, a flushing pipe 29, a gas discharge pipe 30, and an orifice 31. The gas supply pipe 27 is connected to the first gas chamber 1a. The gas supply pipe 27 connects the gas cylinder (gas storage container) 32 filled with He gas and the space of the first gas chamber 1a. A flow control valve 28 is connected to the gas supply pipe 27. Both ends of the flushing pipe 29 are installed in the gas supply pipe 27, bypassing the flow control valve 28. An on-off valve 33 is provided in the flushing pipe 29. The gas cylinder is attached to the outside of the casing of the irradiation nozzle 18. For this reason, the gas supply pipe 27 and the like are also attached to the casing. The gas exhaust pipe 30 is connected to the second gas chamber 1b and communicates with the space in the second gas chamber 1b. The gas exhaust pipe 30 is attached to the casing, and a part thereof is also attached to the rotating gantry. A variable leak valve (micro flow rate adjusting valve) and an orifice 31 are installed in the gas discharge pipe 30.

  The filling gas system includes a pressure switch 35 and a relief valve 36 as a safety system for protecting the isolation windows 3a and 3b. The pressure switch 35 is installed in the gas supply pipe 27. The relief valve 36 is also attached to the gas exhaust pipe 30. A buffer region 37 is formed in the gas discharge pipe 30 between the variable leaf valve 34 and the orifice 31. In order to facilitate the preparation of a minute flow rate under a minute differential pressure, a variable leak valve 34 and an orifice 31 are provided, and a buffer region 37 is formed. In this embodiment, the gas chamber 1 is filled with an inert gas. However, a vacuum chamber may be installed in place of the gas chamber 1 to keep the inside in a vacuum. In this case, the vacuum includes quasi-vacuum. Thus, the same effect can be acquired by keeping the inside of a vacuum chamber in a vacuum. In that case, a vacuum pump (not shown) is installed in the gas chamber 1 instead of the gas flow path system. In addition, the gas chamber in this specification shows the chamber by which the inside was satisfy | filled with the inert gas, or the chamber by which the inside was maintained by the semi-vacuum.

  Next, a movable mechanism and a driving method of the gas chamber 1 in the present embodiment will be described with reference to FIG. As shown in FIG. 4A, the second gas chamber 1b is divided into nodes 38 having a cylindrical structure, and the inner diameter and outer diameter of each node 38 increase toward the downstream side. . When the second gas chamber 1b expands and contracts, as shown in FIG. 4B, cylindrical nodes 38 having different sizes for each node overlap each other. Thus, the full length of the gas chamber 1 can be changed because the 2nd gas chamber 1b expands and contracts. The inside of each node 38 is kept airtight with the outside by a sealing seal 39 and shielding windows 3a and 3b. FIG. 4A shows a configuration of the gas chamber 1 at the time of scanning irradiation in which the beam is irradiated using the first irradiation unit 17a, and FIG. 4B shows an irradiation of the beam using the second irradiation unit 17b. The structure of the gas chamber 1 at the time is shown. In addition, it may replace with the movable mechanism of the gas chamber 1 shown in FIG. 4, and may employ | adopt the 2nd gas chamber 1b of the bellows structure 40 as shown in FIG. The second gas chamber 1b can be expanded and contracted, whereby the overall length of the gas chamber 1 can be changed. Further, in place of the movable mechanism of the gas chamber 1 shown in FIG. 4, as shown in FIG. 6, a spring 41 that is stretchable and has sufficient strength is covered with a cloth-like material 42 having elasticity and strength. May be employed in the second gas chamber 1b. Regarding these two expansion / contraction mechanisms, it is difficult to install a gas discharge pipe in the second gas chamber 1b main body because a flexible material is used. Therefore, the rigid ring 43 is connected between the second gas chamber 1b and the isolation window 3b on the downstream side of the second gas chamber 1b, and the gas discharge pipe 30 is connected to this portion.

  The drive mechanism of the movable second gas chamber 1b shown above will be described. As a driving method, the motor driving shown in FIG. The two rails 44 are fixed so as to face each other outside the first gas chamber 1a. A grooved long axis 45 having an appropriate length is fixed on each rail 44 so as to be movable on the rail 44 in the beam axis direction. The long shaft 45 has a groove, and the gear 47a attached to the motor 46 engages with the groove, so that the long shaft 45 moves along the beam path. The distal end portion 48 on the downstream side of the long shaft 45 is attached to the shielding window 3b or the rigid ring 43 attached to the downstream side of the second gas chamber 1b or the second gas chamber 1b itself. The rigid ring 43 is connected between the second gas chamber 1b and the isolation window 3b on the downstream side of the second gas chamber 1b. The gear 47a moves on the rail 44 along the beam path in the beam axis direction, so that the entire second gas chamber 1b is expanded and contracted. The rail 44 and the motor 46 are installed so as not to interfere with the scanning electromagnets 2b and 2b. As a means for transmitting the driving force of the motor 46, a method using a screw 47b as shown in FIG. 7B is also effective instead of the gear 47a. In this case, the second gas chamber 1b is moved by moving up and down the beam axis direction while rotating the shaft.

  Next, an outline of the scanning irradiation method realized by the irradiation nozzle 18 (first irradiation unit 17a) of the present embodiment will be described below.

  When using the scanning irradiation method, the control device 19 confirms whether or not the first irradiation unit 17 a is arranged on the beam axis in the irradiation nozzle 18. When the second irradiation unit 17b is arranged on the beam axis, the control device 19 moves the second irradiation unit 17b outside the beam axis and outside the region through which the beam in the irradiation nozzle 18 passes. That is, the rotator 11a moves in the direction perpendicular to the beam axis about the rotation shaft portion 11b, so that the scatterer 12, the SOBP filter 13, and the range shifter 14 installed on the rotator 11a are moved out of the beam axis. Moving. The 2nd irradiation part 17b moves to the position which does not interfere when the 2nd gas chamber 1b expands and contracts. The control device 19 confirms that the second irradiation unit 17b has moved to a predetermined position, and extends the second gas chamber 1b in a direction parallel to the beam axis. The 2nd gas chamber 1b is extended until the front-end | tip part reaches the beam monitor 4b. When the second gas chamber 1b is installed at a predetermined position, the control device 19 controls the flow rate control valve 28 so that the gas chamber 1 is filled with He gas, which is an inert gas. The bolus 7 is removed from the beam axis, and the collimator 5 is opened to the maximum.

  The bed 16 on which the patient 15 lies is moved and positioned so that the affected area lies on the extension of the beam axis. In the scanning irradiation method, the affected part is divided into a plurality of layers in the beam traveling direction, and the beam is irradiated for each layer. The beam 10 guided to the irradiation nozzle 18 is scanned in the X direction and the Y direction by the pair of scanning electromagnets 2 a and 2 b and passes through the He gas atmosphere in the gas chamber 1. First, a scanning electromagnet capable of scanning a beam in the X direction is excited with respect to a certain layer, and the beam is scanned to a predetermined position in the X direction. Next, the beam scanning in the Y direction is performed in the same procedure, and the two-dimensional beam scanning to the predetermined irradiation position determined in the treatment plan is completed. When the movement is completed, the beam is irradiated, and the beam is stopped when the predetermined dose is completed. When irradiation is completed, the excitation amount of the scanning electromagnet changes according to the treatment plan, and the two-dimensional beam scanning is performed again toward the next predetermined irradiation position. In this way, beam irradiation is performed while moving and stopping the beam within one layer. A series of irradiation methods in which the irradiation position is changed discretely and beam irradiation is performed is called a discrete spot scanning irradiation method. In this embodiment, the discrete spot scanning irradiation method is adopted as the irradiation method in the X and Y directions of the scanning irradiation method, but the same effect can be obtained when the raster scanning irradiation method is used. The raster scanning irradiation method refers to a method in which continuous beam irradiation is performed by continuously irradiating a beam while changing the excitation amount of the scanning electromagnet, that is, while changing the irradiation position of the beam.

In the scanning irradiation method, when irradiation within one layer is completed, the energy of the beam emitted from the synchrotron 24 is changed. When the energy of the beam emitted from the synchrotron 24 is set low, beam scanning is performed within a shallow layer, and proton beam irradiation similar to that described above is performed. In this manner, the beam energy is adjusted according to the depth of the affected area, and beam irradiation in the depth direction is performed according to the shape of the affected area (energy stacking).
In this embodiment, the method of changing the energy of the beam accelerated by the synchrotron 24 is adopted. However, the same effect can be obtained by changing the beam energy by inserting a range shifter having an arbitrary thickness on the beam axis. Obtainable.

  Next, an outline of the scatterer irradiation method realized by the irradiation nozzle 18 (second irradiation unit 17b) of the present embodiment will be described. A wobbler irradiation method, which is a typical example of the scatterer irradiation method, will be described below.

  When using the wobbler irradiation method, the control device 19 confirms whether or not the second irradiation unit 17 b is arranged on the beam axis in the irradiation nozzle 18. When the second gas chamber 1b of the first irradiation unit 17a is installed in the extended state, the control device 19 contracts the second gas chamber 1b in the beam traveling direction. The second gas chamber 1b is shortened to a predetermined position downstream of the scanning electromagnet 2b by the function of expanding and contracting with respect to the beam traveling direction. At this time, the control device 19 performs control so as to remove the inert gas in the gas chamber 1 and fills the air atmosphere in the gas chamber 1. The control device 19 arranges the scatterer 12, the SOBP filter 13, and the range shifter 14 on the beam axis. Specifically, the rotating body 11a is rotated around the rotating shaft portion 11b, and the scatterer 12, the SOBP filter 13, and the range shifter 14 installed on the rotating body 11a are moved on the beam path. As each rotator 11a rotates independently with respect to the rotating shaft 11b, the scatterer 12, the SOBP filter 13, and the range shifter 14 that are most suitable for the patient receiving the beam irradiation are selected. The collimator 5 is moved to an appropriate shape that matches the shape of the affected part. An appropriate bolus 7 is selected according to the shape of the affected part, and is set on the beam axis.

  The bed 16 on which the patient 15 lies is moved and positioned so that the affected area lies on the extension of the beam axis. In the wobbler irradiation method, the scanning electromagnets 2a and 2b are used to scan a beam in a circular shape, and a uniform dose distribution is formed in a direction perpendicular to the beam traveling direction. A scanning electromagnet power source (not shown) is connected to each of the pair of scanning electromagnets 2a and 2b. The scanning electromagnet power supply supplies a current having an appropriate amount of time change to the scanning electromagnets 2a and 2b in accordance with the affected area and the incident energy of the beam. Specifically, in order to scan the beam in a circular shape, the power source of the scanning electromagnets converts alternating currents having the same maximum current value whose polarity is periodically reversed and whose phase is shifted by 90 degrees into the respective scanning electromagnets 2a, 2a, 2b. The maximum current value at this time determines the beam scanning range. The beams scanned by the scanning electromagnets 2 a and 2 b pass through the scatterer 12, the SOBP filter 13, and the range shifter 14. The energy of the beam emitted from the synchrotron 24 is changed according to the depth of the affected area, and the reaching depth of the beam is made to coincide with the affected area. The collimator 5 forms a beam in an appropriate shape that matches the shape of the affected part in a direction perpendicular to the beam traveling direction. Further, the bolus 7 adjusts the beam arrival depth so as to match the shape of the affected part in the beam traveling direction. As a result, the irradiation dose concentrates in the set affected area, and an irradiation field having a uniform dose distribution is formed as much as possible.

  According to the present embodiment, the following effects can be obtained.

  (1) In this embodiment, equipment required for two different irradiation methods, ie, an irradiation method for forming a particle beam irradiation field using a device such as an enlarged Bragg peak forming filter in one irradiation nozzle 18 and a scanning irradiation method. Can be loaded. Moreover, the irradiation nozzle which mounts the apparatus required for these two different irradiation methods can switch a mutual irradiation method easily, and can perform particle beam irradiation. Therefore, the particle beam therapy system does not require two beam lines, treatment rooms, and irradiation nozzles in order to cope with two different irradiation methods, and the size of the affected area of the patient can be increased with one beam line, treatment room, and irradiation nozzle. Therefore, efficient particle beam irradiation can be performed. Therefore, the cost of the particle beam therapy system can be reduced as compared with the prior art. Accordingly, the facility equipped with the particle beam therapy system can be made compact.

  (2) In the present embodiment, the scatterer 12, the SOBP filter 13, and the range shifter 14 are installed on the rotator 11a, and the rotator 11a is rotated about the rotation shaft portion 11b, whereby the scatterer 12, An SOBP filter 13 and a range shifter 14 are arranged. Since a plurality of scatterers 12, SOBP filters 13, and range shifters 14 can be installed on the rotator 11a, there is no need to replace each patient. In addition, in the structure which rotates and moves the scatterer 12, the SOBP filter 13, and the range shifter 14, the irradiation nozzle 18 with respect to a direction perpendicular | vertical to a beam axis can be reduced compared with the case where it moves by a slide type.

  (3) In a present Example, the rigid body is used for the expansion-contraction part of the 2nd chamber, and it has high intensity | strength. Therefore, the inside of the chamber can be kept at a high vacuum. If the inside of the gas chamber is kept at a high vacuum, scattering of the beam can be further suppressed.

  (4) When the gas chamber shown in FIGS. 5 and 6 of this embodiment is employed, the diameter of the second gas chamber at each position in the beam axis direction can be made constant. Therefore, the rotation axis 11 of the second irradiation unit 17b can be brought close to the beam axis, and a compact irradiation nozzle is realized. In addition, the drive mechanism for expansion and contraction can be stored in a compact manner.

  (5) If the gas chamber having the expansion / contraction mechanism is not provided, the irradiation nozzle cannot suppress beam scattering during scanning irradiation. Therefore, since this embodiment has a gas chamber having an expansion / contraction mechanism, it is possible to suppress the spread of the beam and to prevent a high dose from being applied to normal tissues other than the affected part.

  The proton beam therapy apparatus 100a of the present embodiment has a configuration in which the drive mechanism (motor drive shown in FIG. 7) of the second gas chamber 1b is replaced with the hydraulic drive shown in FIG. Have. Hereinafter, a configuration different from that of the first embodiment will be described.

As shown in FIG. 8, the second gas chamber 1b of the present embodiment uses a hydraulic cylinder as a drive system. The hydraulic cylinder 49 is attached to the first gas chamber 1a so as not to interfere with the scanning electromagnets 2a and 2b. The movable portion tip 50 of the hydraulic cylinder 49 is attached to the shielding window 3b or the rigid ring 43 attached to the downstream portion of the second gas chamber 1b or the second gas chamber 1b itself. The rigid ring 43 is connected between the second gas chamber 1b and the isolation window 3b on the downstream side of the second gas chamber 1b. The hydraulic cylinder 49 moves in the beam axis direction along the beam path, so that the entire second gas chamber 1b is expanded and contracted. Next, the hydraulic system 51 of the hydraulic cylinder 49 will be described.
The hydraulic system 51 is installed outside the casing of the irradiation nozzle 18. The hydraulic system 51 includes a hydraulic control unit 52, a hydraulic pump 53, an oil tank 54, a hydraulic gauge 55, and a safety valve 56. The hydraulic control unit 52 controls the hydraulic cylinder 49 to have any appropriate length by adjusting the pressure inside the hydraulic cylinder 49. A hydraulic control unit 52 is connected to the hydraulic pump 53. The hydraulic pump 53 sends an appropriate amount of oil from the oil tank 54 into the hydraulic cylinder 49 according to the control of the hydraulic control unit 52. Further, the hydraulic control unit 52 is connected to the hydraulic gauge 55 and the safety valve 56. The hydraulic control unit 52 is configured to measure the pressure of the hydraulic cylinder 49 using a hydraulic gauge 55 and to release oil to the oil tank 54 using a safety valve 56 when an abnormal pressure is detected.

  Also in the present embodiment, the same effects as (1) to (5) of the first embodiment can be obtained. Furthermore, the following effects can be obtained.

  (6) When the hydraulic drive is employed as in the present embodiment, the heavy object can be driven more stably than the motor drive. Also, the hydraulic drive can achieve the same force as the motor drive with a more compact configuration. Therefore, a compact irradiation nozzle that realizes stable expansion and contraction of the second chamber can be configured.

  The proton beam therapy apparatus 100b of the present embodiment has a configuration in which the drive mechanism (motor drive shown in FIG. 7) of the second gas chamber 1b is replaced with the air cylinder shown in FIG. 9 in the proton beam therapy apparatus 100 of the first embodiment. Have. Hereinafter, a configuration different from that of the first embodiment will be described.

  The second gas chamber 1b of this embodiment uses a pneumatic cylinder as shown in FIG. The pneumatic cylinder 57 is attached to the first gas chamber 1a so as not to interfere with the scanning electromagnets 2a and 2b. The movable portion tip 58 of the pneumatic cylinder 57 is attached to the downstream shielding window 3b or the rigid ring 43 of the second gas chamber 1b or the second gas chamber 1b itself. The pneumatic cylinder 57 moves in the beam axis direction along the beam path, so that the entire second gas chamber 1b is expanded and contracted. Next, the pneumatic system 59 of the pneumatic cylinder 57 will be described. A pneumatic system 59 of the pneumatic cylinder 57 is installed in the irradiation nozzle 18. The pneumatic system 59 includes a pneumatic control unit 60, a compressor 61, an air pressure gauge 62, and a safety valve 63. The air pressure control unit 60 is connected to the compressor 61, the air pressure gauge 62, and the safety valve 63. The pneumatic control unit 60 controls the pneumatic cylinder 57 to have any appropriate length by adjusting the pressure inside the pneumatic cylinder 57. The compressor 61 sends an appropriate amount of air into the pneumatic cylinder 57 under the control of the pneumatic control unit 60. The air pressure control unit 60 measures the pressure of the air pressure cylinder 57 using the air pressure gauge 62, and when an abnormal pressure is detected, the air pressure control unit 60 opens the air to the atmosphere using the safety valve 63. . In addition to the drive mechanisms such as the motor of the first embodiment, the hydraulic cylinder of the second embodiment, and the pneumatic cylinder of the third embodiment described above, the second chamber 1b is expanded and contracted by adjusting the internal gas pressure. There may be.

  Also in the present embodiment, the same effects as (1) to (5) of the first embodiment can be obtained. Furthermore, the following effects can be obtained.

  (7) In the pneumatic driving, since the fluid used for driving is air, a hose and the like for supplying air can be lightened. Therefore, by adopting pneumatic driving as in the present embodiment, an increase in the weight of the irradiation nozzle can be suppressed, and the burden on the rotating gantry is reduced. Compared with hydraulic drive, pneumatic drive is more resistant to impact and does not cause contamination of the irradiation chamber due to oil leakage.

  The proton beam therapy apparatus 100c of the present embodiment has a configuration in which the configuration of the second gas chamber 1b in the proton beam therapy apparatus 100 of the first embodiment is replaced with the second gas chamber 1c shown in FIG. Hereinafter, a configuration different from that of the first embodiment will be described.

  In this embodiment, in order to realize a plurality of irradiation methods (for example, a scanning irradiation method and a scatterer irradiation method) in one treatment room (or the irradiation apparatus 20), the second gas chamber 1c is replaced with a plurality of chamber portions 1d. Divide into Each chamber portion 1d is installed on each rotating body 11a of the movable jig. The 2nd gas chamber 1c is divided | segmented into the chamber part 1d of the length which does not prevent rotation of each rotary body. Each chamber portion 1d rotates around the rotation shaft portion 11b in the same manner as the scatterer 12, the SOBP filter 13, and the range shifter 14. The second gas chamber 1c can change the occupancy rate of the gas chamber 1 in the beam path in the irradiation nozzle 18 in the same manner as in the first embodiment by rotating the rotating body 11a. Shielding windows 3c are installed at both ends (upstream and downstream ends) of each chamber portion 1d to maintain the airtightness inside each chamber portion 1c. In the first embodiment, the second gas chamber 1b and the first gas chamber 1a are connected to each other by a flange. However, in the present embodiment, the second gas chamber 1c and the first gas chamber 1a are divided. Therefore, in order to maintain the airtightness of the first gas chamber 1a, a shielding window (not shown) is installed on the downstream side of the first gas chamber 1a.

  In the case of performing the scanning irradiation method in the present embodiment, the second gas chamber 1c is disposed on the beam path as shown in FIG. That is, when each chamber part 1d is not arrange | positioned on a beam axis, the control apparatus 19 rotates the rotary body 11a centering on the rotating shaft part 11b, and arranges each chamber part 1d in a line along a beam axis. . Since the chamber portions 1d are arranged along the beam path, the beam 10 can pass through the He gas for a sufficiently long time, and the enlargement of the beam diameter irradiated to the patient can be prevented. As a result, a scanning irradiation method using a beam having a small beam diameter is enabled.

  When performing the scatterer irradiation irradiation method in the present embodiment, as shown in FIG. 10B, the chamber portion 1d on the rotating body 11a is rotated about the rotating shaft portion 11b so that it is off the beam axis. It is removed from the region (beam path) through which the beam passes in the irradiation nozzle 18. Instead, the scatterer 12, the SOBP filter 13, and the range shifter 14 installed on the rotating body 11a are installed on the beam path. At this time, each rotator 11a is independently rotated with respect to the rotating shaft portion 11b, whereby the scatterer 12, the SOBP filter 13, and the range shifter 14 that are most suitable for the patient receiving the beam irradiation are selected.

  In the present embodiment, each chamber portion 1d is preliminarily filled with gas. Since the second gas chamber 1c can be easily removed from the rotating body 11a in the same manner as the scatterer 12, the SOBP filter 13, and the range shifter 14, if the enclosed gas leaks and is lost, it can be refilled and replaced. Can do.

  Also in the present embodiment, the same effects as (1) to (5) of the first embodiment can be obtained.

  (8) By dividing the second gas chamber as in the present embodiment and adopting a configuration like the gas chamber 1c, the need for a gas flow path system is eliminated. Moreover, it installs in the 2nd irradiation part 17b with apparatuses, such as a gas chamber and a SOBP filter. Therefore, it is not necessary to add a new movable mechanism. The increase in the number of irradiation nozzles can be suppressed. Furthermore, since the gas chamber can be easily removed and replaced, the maintainability is improved.

  The proton beam therapy apparatus 100d of the present embodiment has a configuration in which the irradiation nozzle 18 in the proton beam therapy apparatus 100 of the first embodiment is replaced with an irradiation nozzle 18a illustrated in FIG. Hereinafter, a configuration different from that of the first embodiment will be described.

  In the irradiation nozzle 18b of the present embodiment, the second irradiation unit 17b is disposed inside the second gas chamber 1b. The second gas chamber 1b of the present embodiment is larger than the second gas chamber 1b of the first embodiment. Even with such a configuration, a plurality of irradiation methods (for example, a scanning irradiation method and a scatterer irradiation method) can be realized in one treatment room (or irradiation device 20).

  The second gas chamber 1b of the gas chamber 1 is expanded and deformed in a direction perpendicular to the beam traveling direction as shown in FIG. A second irradiation unit 17b (movable jig) in which the scatterer 12, the SOBP filter 13, and the range shifter 14 are installed is housed in the enlarged deformed part of the second gas chamber 1b. The gas chamber 1 is filled with He gas through a gas flow path system as shown in FIG.

  In this embodiment, when the scanning irradiation method is performed, the rotator 11a of the movable jig containing the scatterer 12, the SOBP filter 13, and the range shifter 14 is rotated about the rotation shaft portion 11b, whereby the scatterer 12 , SOBP filter 13 and range shifter 14 are removed from the beam path.

  In the present embodiment, when the scatterer irradiation method is performed, the rotator 11a installed in the enlarged deformed portion of the second gas chamber 1b rotates around the rotating shaft portion 11b, whereby the scatterer 12 and the SOBP filter 13 are obtained. The range shifter 14 is installed on the beam path. At this time, each rotator 11a is independently rotated with respect to the rotating shaft portion 11b, whereby the scatterer 12, the SOBP filter 13, and the range shifter 14 that are most suitable for the patient receiving the beam irradiation are selected.

  Also in this embodiment, the same effects as (1) and (2) of Embodiment 1 can be obtained. Furthermore, the following effects can be obtained.

  (9) According to the present embodiment, since the second irradiation unit 17b is arranged in the second gas chamber 1b, the movable mechanism of the second gas chamber necessary for switching the irradiation method is not required. Therefore, an increase in the number of irradiation nozzles can be suppressed.

  In the first to fifth embodiments, the wobbler irradiation method is adopted as means for forming a dose distribution as uniform as possible in the direction perpendicular to the beam traveling direction in the scatterer irradiation method. However, the discrete spot scanning irradiation method and the raster scanning irradiation method are used. May be adopted. Even when a discrete spot scanning irradiation method or a raster scanning irradiation method is employed, the apparatus configuration is the same as that of the first to fifth embodiments. At that time, in order to obtain the effects of shortening the beam scanning distance and time, and relaxing the required beam scanning accuracy, a means for expanding the beam diameter by installing a scatterer on the beam path can be selected. When using these scatterer irradiation methods, the second irradiator 17b is provided with the range shifter 14, the SOBP filter 13, and the scatterer 12 in order from the patient receiving irradiation (in order from the downstream side of the beam axis). The The range shifter 14, SOBP filter 13, and scatterer 12 are selected according to the shape and position of the affected area of the patient 15 that is irradiated with the particle beam. Furthermore, the irradiation dose at each irradiation position of the patient is measured and recorded by the beam monitor. For the irradiation position where the measured irradiation dose reaches the predetermined dose, the beam irradiation ends, and for the irradiation position that does not reach the predetermined dose, multiple beam scans and irradiations are repeated until the predetermined dose is reached. An irradiation method for obtaining a uniform dose distribution is also effective as a means for forming a uniform dose distribution in a direction perpendicular to the beam traveling direction in the scatterer irradiation method. When using these scatterer irradiation methods, the range shifter 14, the SOBP filter 13, and the scatterer 12 are installed in the second irradiation unit 17b in order from the patient receiving irradiation. The range shifter 14, SOBP filter 13, and scatterer 12 are selected according to the shape and position of the affected area of the patient 15 that is irradiated with the particle beam.

  In the first to fifth embodiments, the SOBP filter 13 is used as means for forming a uniform dose distribution in the beam traveling direction in the scatterer irradiation method. However, instead of the SOBP filter 13, energy stacking is used. Is also effective. When performing energy stacking, it can be selected that a mini SOBP filter is installed on the beam path instead of the SOBP filter 13. The mini SOBP filter widens the Bragg peak of the beam in a distribution having a certain extent, for example, a Gaussian distribution, as compared with a normal SOBP filter that can create an enlarged Bragg peak that covers the shape of the affected part. Therefore, when a mini SOBP filter is used, the number of energy required for energy stacking can be reduced.

  In the first to fifth embodiments, the rotary method is adopted as the movable method of the movable jig 11, but the same effect can be obtained by using a slide base. When a slide base is used, the scatterer 12, the SOBP filter 13, and the range shifter 14 are installed on a base (not shown) that slides in a direction perpendicular to the beam path direction. When the movable part 1b of the gas chamber 1 is moved and folded at the upstream part of the irradiation nozzle 18, the base slides on the beam path and comes out, so that the scatterer 12, the SOBP filter 13, and the range shifter. 14 can be installed on the beam path. On the contrary, the scatterer 12, the SOBP filter 13, and the range shifter 14 can be removed from the beam path by sliding the platform to avoid the beam path, and the movable part 1b of the gas chamber 1 is moved to extend the gas chamber 1. it can.

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 irradiation field formation apparatus with which the proton beam treatment system which is one preferable Example of this invention is equipped. It is a block diagram of the filling gas system | strain of the gas chamber with which an irradiation field forming apparatus is equipped. It is a block diagram which shows the movable system of the gas chamber with which an irradiation field forming apparatus is equipped. It is another block diagram which shows the movable system of the gas chamber with which an irradiation field forming apparatus is equipped. It is another block diagram which shows the movable system of the gas chamber with which an irradiation field forming apparatus is equipped. It is a block diagram which shows the drive method of the 2nd gas chamber with which an irradiation field forming apparatus is equipped. It is another block diagram which shows the drive method of the 2nd gas chamber with which an irradiation field forming apparatus is equipped. It is another block diagram which shows the drive system of the 2nd gas chamber with which an irradiation field forming apparatus is equipped. It is a block diagram of the irradiation field forming apparatus with which the proton beam treatment system which is another suitable Example of this invention is equipped. It is a block diagram which shows a part of structure of the irradiation field forming apparatus with which the proton beam treatment system which is another suitable Example of this invention is equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas chamber 1a 1st gas chamber 1b, 1c 2nd gas chamber 1d Chamber part 2a, 2b Scanning electromagnet 3a, 3b, 3c Shielding window (isolation window)
4a, 4b Beam monitor 5 Collimator 6 Snout 7 Bolus 8 Vacuum beam duct 9 Vacuum shielding window 11a Rotating body 11b Rotating shaft 12 Scattering body 13 SOPB filter 14 Range shifter 15 Patient 16 Bed 18 Irradiation field forming device (irradiation nozzle)
DESCRIPTION OF SYMBOLS 20 Irradiation device 21 Beam path 22 Beam transport device 23 Output deflector 24 Synchrotron 25 Beam generator 26 Pre-accelerator 27 Gas supply pipe 28 Flow control valve 29 Flushing pipe 30 Gas discharge pipe 31 Orifice 32 Gas cylinder 33 On-off valve 34 Variable leak valve 35 Pressure switch 36 Relief valve 37 Buffer area 38 Node 39 Airtight seal 40 Bellows structure 41 Spring 42 Elastic cloth material 43 Rigid ring 44 Rail 45 Long shaft 46 Motor 47a Gear 47b Screw 49 Hydraulic cylinder 51 Hydraulic system 51 Hydraulic control unit 53 Hydraulic pump 54 Oil tank 55 Hydraulic gauge 56, 63 Safety valve 57 Pneumatic cylinder 59 Pneumatic system 60 Pneumatic control unit 61 Compressor 62 Pneumatic gauge

Claims (7)

A beam generator for accelerating a charged particle beam to a set energy;
An irradiation field forming device arranged in a treatment room and forming an irradiation field of a charged particle beam;
A beam transport device that transports the charged particle beam emitted from the beam generator to the irradiation field forming device;
The irradiation field forming device comprises:
An electromagnet that scans the charged particle beam incident on the irradiation field forming device;
A first irradiation unit having a gas chamber;
A second irradiation unit having a scatterer for adjusting the amount of scattering of the charged particle beam,
A control device that performs switching control so that either the second irradiation unit or the first irradiation unit having the gas chamber filled with an inert gas is disposed on the beam axis in the irradiation field forming device. A particle beam therapy system comprising: A beam generator for accelerating a charged particle beam to a set energy;
An irradiation field forming device arranged in a treatment room and forming an irradiation field of a charged particle beam;
A beam transport device that transports the charged particle beam emitted from the beam generator to the irradiation field forming device;
The irradiation field forming device comprises:
An electromagnet that scans the charged particle beam incident on the irradiation field forming device;
A first irradiation unit having a vacuum chamber;
A second irradiation unit having a scatterer for adjusting the amount of scattering of the charged particle beam,
A control device is provided that performs switching control so that either the second irradiation unit or the first irradiation unit having the vacuum chamber in which the inside is maintained in a vacuum is disposed on the beam axis in the irradiation field forming device. A particle beam therapy system characterized by that.   3. The control device according to claim 1, wherein the control device performs switching control by moving the second irradiation unit on a beam axis in the irradiation field forming device or outside a region through which the charged particle beam passes. Particle beam therapy system.   The particle beam therapy system according to claim 1, wherein the gas chamber is configured to be extendable and contractible in a direction parallel to a beam axis in the irradiation field forming device. The second irradiation unit having the scatterer is disposed in the gas chamber,
The control device controls the gas chamber to be filled with an inert gas when the second irradiation unit is located outside the region through which the charged particle beam passes in the irradiation field forming device , When the second irradiation unit is located in a region through which the charged particle beam passes in the irradiation field forming apparatus, control is performed so as to discharge the inert gas from the inside of the gas chamber. Item 5. A particle beam therapy system according to Item 1 or 4.   The particle beam therapy system according to claim 2, wherein the vacuum chamber is configured to be extendable and contractible in a direction parallel to a beam axis in the irradiation field forming apparatus. The second irradiation unit further includes an enlarged Bragg peak forming filter and a range shifter,
The scatterer, the enlarged black peak forming filter, and the range shifter are configured to be independently movable on a beam axis in the irradiation field forming apparatus or outside a region through which the charged particle beam passes. The particle beam therapy system according to any one of claims 1 to 6.

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