Neutron capture therapy device and target replacement method

Abstract

To provide a neutron capture therapy device and a target replacement method that enable target replacement in a space-saving manner while suppressing radiation exposure to a worker.SOLUTION: A neutron capture therapy device 1 includes a plurality of shielding members 25 that covers the periphery of a target 5. During the normal operation, the plurality of shielding members 25 is able to shield radiation from the target 5. The target 5 and one second shielding member 22 are configured to be movable to a replacement work position PG2 where the replacement work for the target 5 is performed. By moving not only the target 5 but also the second shielding member 22 to the replacement work position PG2, a worker WP can perform work on the target 5 while shielding the radiation with the second shielding member 22. A space required to move the target 5 and the second shielding member 22 is significantly smaller than a space required for a device that automatically replaces the target 5.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a neutron capture therapy apparatus and a target exchange method.

Background Art

[0002] As a neutron capture therapy for killing cancer cells by irradiating neutron rays, boron neutron capture therapy (BNCT) using a boron compound is known. As a neutron capture therapy apparatus used in such boron neutron capture therapy, Patent Document 1 describes a neutron capture therapy apparatus including a cyclotron that emits a charged particle beam and a target that generates neutron rays when irradiated with the charged particle beam.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the neutron capture therapy apparatus as described above, it is necessary to exchange the target. In order to perform the exchange of the target, an exchange device is provided so that the exchange operation can be performed automatically (a manual process may be included in the process). For example, a mechanism for recovering the target is provided on the lower floor of the room where the target is provided, and an apparatus that automatically drops and recovers the target can be mentioned. However, such a target exchange device is large-scale and the device becomes large. Therefore, there is a problem that the space required for target exchange becomes too large.

[0005] On the other hand, when attempting to save space without using a target exchange device, an operator must perform the target exchange operation while suppressing exposure.

[0006] Therefore, an object of the present invention is to provide a neutron capture therapy apparatus and a target replacement method that can suppress exposure of an operator and can replace a target in a space-saving manner.

Means for Solving the Problems

[0007] In one embodiment, the neutron capture therapy apparatus of the present invention is a neutron capture therapy apparatus that irradiates a subject with neutron rays, and includes a target that generates neutron rays by irradiating a particle beam, and a plurality of shielding members that cover the periphery of the target and shield radiation from the target. The target and at least one shielding member are configured to be movable to an exchange work position where the target is exchanged.

[0008] This neutron capture therapy apparatus includes a plurality of shielding members that cover the periphery of the target and shield radiation from the target. Therefore, during normal operation, the plurality of shielding members can shield radiation from the target. Here, the target and at least one shielding member are configured to be movable to an exchange work position where the target is exchanged. In this case, by opening the shielding member from the state during normal operation and shifting the target to a position different from the axis of the particle beam, it is possible to avoid interference with beam transport or the like and secure a place where the target can be exchanged. Further, by moving not only the target but also the shielding member to the exchange work position, the operator can perform work on the target while shielding radiation with the shielding member. The space required to move the target and the shielding member is significantly smaller than the space required for an apparatus that automatically (which may include a manual process within the process) exchanges the target. From the above, it is possible to replace the target in a space-saving manner while suppressing exposure of the operator.

[0009] The target may be movable to the exchange work position together with the shielding member. In this case, the movement mechanism of the shielding member and the movement mechanism of the target can be shared. Thereby, further space saving can be achieved.

[0010] The target may have a horizontal movement component and be movable to the replacement work position. In this case, in order to move the target, it is possible to suppress providing a mechanism that increases the vertical space.

[0011] The neutron capture therapy device has a work position where an operator who replaces the target works, and the work position may be provided at a position where a shielding member disposed at the replacement work position is interposed between the work position and the target disposed at the replacement work position. In this case, when the operator is working at the work position, the shielding member can shield radiation from the target.

[0012] The neutron capture therapy device further has a target duct that holds the target, and the plurality of shielding members include a first shielding member whose position is fixed and a second shielding member that moves to the replacement work position. The first shielding member and the second shielding member may be provided with a transfer mechanism for switching the target duct from a state supported by the first shielding member to a state supported by the second shielding member. In this case, during normal operation, the position of the target duct can be reliably fixed by the fixed first shielding member. On the other hand, when replacing the target, the target duct can be moved to the replacement work position together with the second shielding member.

[0013] In one embodiment, the target replacement method of the present invention is a target replacement method for replacing a target that generates neutron rays by irradiating a particle beam in a neutron capture therapy device that irradiates a subject with neutron rays. The neutron capture therapy device includes a plurality of shielding members that cover the periphery of the target and shield radiation from the target, and a target duct that holds the target. The target, the target duct, and at least one shielding member are moved to a replacement work position where the target replacement work is performed, and the target duct and the target are placed on a cart and transported from the replacement work position.

[0014] According to this target exchange method, the neutron capture therapy device includes a plurality of shielding members that cover the periphery of the target and shield the radiation from the target. Therefore, during normal operation, the plurality of shielding members can shield the radiation from the target. Here, the target and at least one shielding member are configured to be movable to an exchange work position where the target exchange work is performed. In this way, by moving not only the target but also the shielding member to the exchange work position, the operator can perform the work on the target while shielding the radiation with the shielding member. Further, the target duct and the target are placed on a cart and conveyed from the exchange work position. The cart on which the target duct is placed has a sufficient length in the longitudinal direction. Therefore, the operator can perform the work on the end side of the cart on the side opposite to the target, ensuring a sufficient distance from the target and performing the work in a state where exposure is suppressed. Also, the space required to move the target and the shielding member and the space to operate the cart are significantly smaller than the space required for the device that automatically exchanges the target. From the above, it is possible to exchange the target in a space-saving manner while suppressing the exposure of the operator.

Effects of the Invention

[0015] According to the present invention, it is possible to provide a neutron capture therapy device and a target exchange method capable of exchanging the target in a space-saving manner while suppressing the exposure of the operator.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0017] Hereinafter, a neutron capture therapy apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Also, in the description, the terms "upper" and "lower" may be used, which correspond to the upper and lower directions of the drawings.

[0018] As shown in FIG. 1, a neutron capture therapy apparatus 1 for performing cancer treatment using boron neutron capture therapy is an apparatus that irradiates a neutron beam N to a site where boron has accumulated in a patient P (irradiated object) to whom boron ( 10 B) has been administered for cancer treatment. The neutron capture therapy apparatus 1 has an irradiation chamber 3 that irradiates a neutron beam N to the patient P fixed to the treatment table 2 to perform cancer treatment on the patient P. Further, the neutron capture therapy apparatus 1 includes a cyclotron (accelerator) 4 that generates a charged particle beam L, a target 5 that generates a neutron beam N by receiving the charged particle beam L, a duct structure 10 for guiding the charged particle beam L from the cyclotron 4 to the target 5, and a radiation shield 20 that houses the target 5 and a part of the duct structure 10.

[0019] The cyclotron 4 is an accelerator that accelerates charged particles such as hydrogen ions to generate a charged particle beam L such as a proton beam. Instead of the cyclotron 4, other accelerators such as a synchrotron, a synchrocyclotron linac, or an electrostatic accelerator may be used.

[0020] The target 5 generates a neutron beam N when irradiated with the charged particle beam L emitted from the cyclotron 4. The target 5 is made of a material such as beryllium (Be) and has a disk shape. The neutron beam N generated by the target 5 has its irradiation field defined by the collimator 6 and is irradiated to the affected part of the patient P in the irradiation chamber 3. Instead of the target 5 made of beryllium, a target made of lithium (Li), tantalum (Ta), or tungsten (W) may be used, and the size of the target can also be appropriately changed.

[0021] As shown in FIGS. 1 and 2, the duct structure 10 includes a beam transport 11 connected to the cyclotron 4, a target duct 12 connected to the target 5, and a connection duct 13 connected to the opposite side of the cyclotron 4 in the beam transport 11. One end of the target duct 12 is connected to the target 5, and the other end of the target duct 12 is connected to the beam transport 11 via the connection duct 13. The ducts 11 to 13 are arranged inside a duct arrangement chamber 30 that is substantially rectangular in plan view. This duct arrangement chamber 30 is an enclosed space covered by a concrete shielding wall W.

[0022] Note that the duct arrangement chamber 30 does not necessarily have to be substantially rectangular in plan view, and may have other shapes such as an L-shape. Also, the cyclotron 4 does not necessarily have to be arranged inside the duct arrangement chamber 30, and may be arranged in another room outside the duct arrangement chamber 30.

[0023] One end of the beam transport 11 is connected to the cyclotron 4. The beam transport 11 includes a beam adjustment unit (not shown) for adjusting the charged particle beam L. This beam adjustment unit has a horizontal steering and a horizontal-vertical steering for adjusting the axis of the charged particle beam L, a quadrupole electromagnet for suppressing the divergence of the charged particle beam L, a four-direction slit for shaping the charged particle beam L, and the like. Note that the beam transport 11 only needs to have the function of transporting the charged particle beam L, and the above-described beam adjustment unit may be omitted.

[0024] The beam transport 11 is fixed at the upper end of the column portion 32 protruding upward from the floor surface 31a in the duct arrangement chamber 30. A target duct 12 is fixed further on the side of the radiation shield 20 of the connection duct 13. Also, from the floor surface 31a, a first cooling pipe 51 for supplying cooling water to a target cooling plate (not shown) for cooling the target 5 and a second cooling pipe 52 through which the cooling water discharged from the target cooling plate 50 passes project upward. The first and second cooling pipes 51 and 52 are connected to a cooler for cooling the cooling water below the floor surface 31a. The cooling water reaches the target cooling plate 50 from a cooler located below the floor surface 31a of the base portion 31 through the first cooling pipe 51, the fifth cooling pipe 55, and the third cooling pipe 53, and the cooling water discharged from the target cooling plate 50 is returned to the cooler through the fourth cooling pipe 54, the sixth cooling pipe 56, and the second cooling pipe 52.

[0025] The radiation shield 20 has a plurality of shielding members 25. As the plurality of shielding members 25, a first shielding member 21, a second shielding member 22, and a third shielding member 24 are provided. The first shielding member 21 is fixed in position by being fixed to the floor surface 31a. The second shielding member 22 is provided movably with respect to the first shielding member 21 and can be moved to an exchange work position described later. The third shielding member 24 constitutes a wall portion separating the irradiation chamber 3 and the duct arrangement chamber 30. Each of the shielding members 21, 22, and 24 is made of, for example, concrete. A collimator 6 serving as an output port for the neutron beam N is fixed to the irradiation chamber 3 side of the third shielding member 24 (see FIG. 1).

[0026] As shown in FIG. 1, a moderator 28 is provided in the radiation shield 20. The neutron beam N generated by the target 5 is moderated by the moderator 28 and irradiates the affected part of the patient P in the irradiation chamber 3. The moderator 28 has, for example, a laminated structure composed of a plurality of different materials, and the material of the moderator 28 is appropriately selected according to various conditions such as the energy of the charged particle beam L.

[0027] Specifically, for example, when the output from the cyclotron 4 is a proton beam of 30 MeV and a beryllium target is used as the target 5, the material of the deaccelerator 28 can be lead, iron, aluminum, or calcium fluoride. Further, when the output from the cyclotron 4 is a proton beam of 11 MeV and a beryllium target is used as the target 5, the material of the deaccelerator 28 can be heavy water (D2O) or lead fluoride.

[0028] Also, at the lower part of the second shielding member 22, a rail (not shown) extending in the horizontal direction and perpendicular to the longitudinal direction of the target duct 12 is installed. On the side of the second shielding member 22 opposite to the first shielding member 21, a piston (not shown) for moving the second shielding member 22 on the rail is installed. Since the second shielding member 22 moves on the rail by the drive of the piston, it can move in the direction approaching the first shielding member 21 and in the direction away from the first shielding member 21. In this way, when the second shielding member 22 approaches the first shielding member 21, the radiation shield 20 closes, and when the second shielding member 22 moves away from the first shielding member 21, the radiation shield 20 opens, so the radiation shield 20 can be opened and closed.

[0029] Note that the second shielding member 22 may be moved by means other than the rail and the piston. Further, a mirror may be installed on the side of the second shielding member 22 opposite to the first shielding member 21 so that it is possible to confirm whether a person or an object exists at the moving destination of the second shielding member 22 and whether the second shielding member 22 can be moved safely.

[0030] Next, with reference to FIGS. 3 to 6, a target replacement method for replacing the target 5 will be described. In the following description, among the horizontal directions, the direction in which the beam transport 11 extends may be referred to as the "longitudinal direction", and the direction perpendicular to the longitudinal direction may be referred to as the "width direction".

[0031] FIG. 3 is a view showing the state at the start of the replacement work. In this state, each shielding member 21, 22 is in a closed state. In addition, the position of the second shielding member 22 when the shielding members 21, 22 are in the closed state like this may be referred to as a shielding position PG1. As shown in FIG. 3(b), the first shielding member 21 has opposing surfaces 21a, 21b facing the second shielding member 22, and a stepped surface 21c between the opposing surfaces 21a, 21b. The second shielding member 22 has opposing surfaces 22a, 22b facing the first shielding member 21, and a stepped surface 22c between the opposing surfaces 22a, 22b.

[0032] The opposing surface 21a of the first shielding member 21 is provided on the upper side, and the opposing surface 21b is provided on the lower side. The opposing surface 21a is disposed closer to the second shielding member 22 than the opposing surface 21b. The opposing surfaces 21a, 21b extend parallel to the vertical direction. The stepped surface 21c extends parallel to the horizontal direction so as to connect the lower end of the opposing surface 21a and the upper end of the opposing surface 21b.

[0033] The opposing surface 22a of the second shielding member 22 is provided on the upper side, and the opposing surface 22b is provided on the lower side. The opposing surface 22b is disposed closer to the first shielding member 21 than the opposing surface 22a. The opposing surfaces 21a, 21b extend parallel to the vertical direction. When the second shielding member 22 is in the closed state, the opposing surface 22a is in surface contact with the opposing surface 21a, and the opposing surface 22b is in surface contact with the opposing surface 21b. The opposing surface 22a extends to a position lower than the opposing surface 21a. The opposing surface 21b extends to a position higher than the opposing surface 22b. Therefore, the vicinity of the lower end of the opposing surface 22a and the vicinity of the upper end of the opposing surface 21b face each other in a state of being separated from each other in the width direction. The stepped surface 22c extends parallel to the horizontal direction so as to connect the lower end of the opposing surface 22a and the upper end of the opposing surface 22b. The stepped surface 21c and the stepped surface 22c face each other in a state of being separated in the vertical direction. Thereby, a space SP surrounded by the opposing surfaces 21b, 22a and the stepped surfaces 21c, 22c is formed. The space SP is a space for arranging the target duct 12.

[0034] As shown in Fig. 3(a), the operator WP removes the connection duct 13 with the target duct 12 housed in the shielding members 21 and 22. Next, as shown in Fig. 4, the operator WP pulls out the target duct 12 along the longitudinal direction toward the duct placement chamber 30. The operator WP pulls out the target duct 12 until the end 12a on the duct placement chamber 30 side of the target duct 12 faces a position in front of the end 11a of the beam transport 11.

[0035] Here, the first shielding member 21 and the second shielding member 22 are provided with a transfer mechanism 40 for switching the target duct 12 from a state supported by the first shielding member 21 to a state supported by the second shielding member 22. When the target duct 12 is in the initial state (the state shown in Fig. 3(a)), the transfer mechanism 40 supports it on the first shielding member 21. When the target duct 12 is in the pulled-out state (the state shown in Fig. 4), the transfer mechanism 40 supports it on the second shielding member 22. The transfer mechanism 40 includes a first support portion 41 for supporting on the first shielding member 21 and a second support portion 42 for supporting on the second shielding member 22.

[0036] In this embodiment, the transfer mechanism 40 has a pair of first support portions 41 and a pair of second support portions 42. The second support portion 42, the first support portion 41, the second support portion 42, and the first support portion 41 are provided in this order from the side of the duct placement chamber 30. When the target duct 12 is in the initial state (the state shown in FIG. 3(a)), the first first support portion 41 supports the vicinity of the end of the target duct 12 on the target 5 side. The method of supporting the target duct 12 by the first support portion 41 is not particularly limited, and a regulating plate or the like that restricts the movement of the target duct 12 in both width directions may be used. When the target duct 12 is pulled out toward the duct placement chamber 30 (the state shown in FIG. 4), the target duct 12 is removed from the first first support portion 41, and the first second support portion 42 supports the vicinity of the end of the target duct 12 on the target 5 side. When the target duct 12 is further pulled out toward the duct placement chamber 30, the target duct 12 is removed from the first second support portion 42, and the second first support portion 41 supports the vicinity of the end of the target duct 12 on the target 5 side. When the target duct 12 is further pulled out toward the duct placement chamber 30, the target duct 12 is removed from the second first support portion 41, and the second second support portion 42 supports the vicinity of the end of the target duct 12 on the target 5 side. At this time, the target duct 12 is in a state of being supported only by the second second support portion 42. The second support portion 42 is in a state where the target duct 12 is not connected to the first shielding member 21 and is connected only to the second shielding member 22. The pair of second support portions 42 are provided on the stepped surface 22c and have at least a support member 43 that supports the target duct 12 from below. The support member 43 has an arc-shaped placement surface corresponding to the shape of the outer peripheral surface of the target duct 12, thereby restricting the relative movement of the target duct 12 in both width directions with respect to the second shielding member 22. The pair of first support portions 41 are provided on the stepped surface 21c of the first shielding member 21.

[0037] Next, as shown in FIG. 5, with the target duct 12 pulled out, the second shielding member 22 is moved to the replacement work position PG2. The replacement work position PG2 is a position for performing the replacement work of the target 5. The replacement work position PG2 is a position spaced apart from the shielding position PG1 on the opposite side of the first shielding member 21 in the width direction. The facing surface 22b of the second shielding member 22 disposed at the replacement work position PG2 is disposed at least at a position spaced apart from the facing surface 21a of the first shielding member 21 in the width direction.

[0038] The target 5, the target duct 12, and the second shielding member 22 are configured to be movable to the replacement work position PG2. Therefore, as shown in FIG. 5, during the replacement work, the target 5 and the target duct 12 also move to the replacement work position PG2. The target 5 and the target duct 12 are movable to the replacement work position PG2 together with the second shielding member 22. That is, when the second shielding member 22 moves to the replacement work position PG2, the target duct 12 and the target 5 move to the replacement work position PG2 at the same time. The target 5 has a horizontal movement component and is movable to the replacement work position PG2. In the present embodiment, the target 5 moves parallel to the width direction, which is the horizontal direction. However, the target 5 may have any movement mode other than moving only in the vertical direction during replacement, and may move obliquely with respect to the horizontal direction.

[0039] Note that the target 5 and the target duct 12 do not necessarily have to move at the same time as the second shielding member 22, and may be movable to the replacement work position PG2 after the second shielding member 22 is moved. For example, a mechanism for moving the target duct 12 to the replacement work position PG2 may be provided separately from the second shielding member 22.

[0040] Here, the duct arrangement chamber 30 has a working position PG3 where an operator who replaces the target 5 works. The working position PG3 is provided at a position where a second shielding member 22 disposed at the replacement working position PG2 is interposed between the working position PG3 and the target 5 disposed at the replacement working position PG2. The operator WP working at the working position PG3 is protected from the radiation RD emitted by the target 5 by the second shielding member 22. Specifically, the working position PG3 is set at a position closer to the duct arrangement chamber 30 than the second shielding member 22 and on the opposite side of the first shielding member 21 from the facing surface 22a.

[0041] Next, as shown in FIGS. 5(a) and 6, the operator WP places the target duct 12 and the target 5 on a cart and transports them from the replacement working position PG2. As shown in FIG. 5(a), a portion near the end 12a of the target duct 12 in the state of being pulled out from the second shielding member 22 is placed on the cart 45. The cart 45 is arranged so as to face the second shielding member 22 on the duct arrangement chamber 30 side. The cart 45 is arranged so as to extend in the longitudinal direction at this time. Further, the cart 45 is arranged at a position spaced apart in the width direction from the beam transport 11. Therefore, interference with the beam transport 11 can be avoided when the cart 45 moves. The operator WP is located on the end 45a side of the cart 45 on the side opposite to the target duct 12. For this reason, the longitudinal distance L1 between the target 5 and the operator WP can be set to a distance sufficient to attenuate the radiation RD of the target 5. Therefore, although the second shielding member 22 does not exist between the operator WP and the target 5, exposure of the operator WP can be suppressed. For example, it is preferable to secure a distance L1 of about 2.3 m, for example.

[0042] Next, the operator WP further pulls out the target duct 12 toward the duct placement chamber 30 side, and transfers the entire target duct 12 from the stepped surface 22c of the second shielding member onto the cart 45. At the time of transfer, the operator WP performs the pulling-out operation of the target duct 12 at the working position PG3, and moves to the end 45a side of the cart 45 at the timing when the target 5 approaches the cart 45. Thereby, the operator WP performs the operation of transferring the target duct 12 onto the cart 45 at a position away from the target 5. After the operator WP transfers the target duct 12 onto the cart 45, the operator WP operates the cart 45 to convey the target 5 to another position.

[0043] Next, the operation and effects of the neutron capture therapy device 1 and the target replacement method according to the present embodiment will be described.

[0044] This neutron capture therapy device 1 includes a plurality of shielding members 25 that cover the periphery of the target 5 and shield radiation from the target 5. Therefore, during normal operation, the plurality of shielding members 25 can shield radiation from the target 5. Here, the target 5 and one second shielding member 22 are configured to be movable to the replacement working position PG2 where the replacement operation of the target 5 is performed. In this case, by opening the second shielding member 22 from the state during normal operation and shifting the target 5 to a position different from the axis of the particle beam, it is possible to avoid interference with the beam transport 11 or the like, and secure a place where the target can be replaced. Further, by moving not only the target 5 but also the second shielding member 22 to the replacement working position PG2, the operator WP can perform the work while shielding the radiation with the second shielding member 22 with respect to the target 5. The space required to move the target 5 and the second shielding member 22 is significantly smaller than the space required for a device that automatically replaces the target 5. From the above, it is possible to replace the target in a space-saving manner while suppressing the exposure of the operator WP. Therefore, it is possible to incorporate the neutron capture therapy device 1 even in a hospital with only limited space. Further, the cost of the entire system can be reduced, and the introduction hurdle can be lowered.

[0045] The target 5 may be movable to the replacement work position PG2 together with the second shielding member 22. In this case, the moving mechanism of the second shielding member 22 and the target 5 can be shared. Thereby, further space saving can be achieved.

[0046] The target 5 may be movable to the replacement work position PG2 after moving the second shielding member 22.

[0047] The target 5 may have a horizontal movement component and be movable to the replacement work position PG2. In this case, in order to move the target 5, it is possible to suppress the provision of a mechanism that increases the vertical space.

[0048] The neutron capture therapy apparatus 1 has a work position PG3 where an operator WP who replaces the target 5 works, and the work position PG3 may be provided at a position where the second shielding member 22 disposed at the replacement work position PG2 is interposed between the work position PG3 and the target 5 disposed at the replacement work position PG2. In this case, when the operator WP is working at the work position PG3, the second shielding member 22 can shield the radiation from the target 5.

[0049] The neutron capture therapy apparatus 1 further has a target duct 12 that holds the target 5. The plurality of shielding members 25 include a first shielding member 21 whose position is fixed and a second shielding member 22 that moves to the replacement work position PG2. The first shielding member 21 and the second shielding member 22 may be provided with a transfer mechanism 40 that switches the target duct 12 from a state supported by the first shielding member 21 to a state supported by the second shielding member 22. In this case, during normal operation, the position of the target duct 12 can be reliably fixed by the fixed first shielding member 21. On the other hand, at the time of target replacement, the target duct 12 can be moved to the replacement work position PG2 together with the second shielding member 22.

[0050] The target replacement method of this embodiment is a target replacement method for replacing a target 5 that generates a neutron beam N by irradiating a particle beam in a neutron capture therapy apparatus 1 that irradiates a subject with the neutron beam N. The neutron capture therapy apparatus 1 includes a plurality of shielding members 25 that cover the periphery of the target 5 and shield radiation from the target 5, and a target duct 12 that holds the target 5. The target 5, the target duct 12, and at least one second shielding member 22 are moved to an exchange work position PG2 where the replacement work of the target 5 is performed, and the target duct 12 and the target 5 are placed on a cart 45 and conveyed from the exchange work position PG2.

[0051] According to this target replacement method, the neutron capture therapy apparatus 1 includes a plurality of shielding members 25 that cover the periphery of the target 5 and shield radiation from the target 5. Therefore, during normal operation, the plurality of shielding members 25 can shield radiation from the target 5. Here, the target 5 and at least one second shielding member 22 are configured to be movable to an exchange work position PG2 where the replacement work of the target 5 is performed. In this way, by moving not only the target but also the second shielding member 22 to the exchange work position, the operator can perform the work on the target 5 while shielding the radiation with the second shielding member 22. Further, the target duct 12 and the target 5 are placed on a cart 45 and conveyed from the exchange work position PG2. The cart 45 on which the target duct 12 is placed has a sufficient length in the longitudinal direction. Therefore, the operator WP can perform the work on the end 45a side of the cart 45 on the side opposite to the target 5, ensuring a sufficient distance from the target 5 and performing the work in a state where exposure is suppressed. Also, the space required to move the target 5 and the second shielding member 22 and the space for operating the cart 45 are significantly smaller than the space required for an apparatus that automatically replaces the target 5. From the above, it is possible to replace the target 5 in a space-saving manner while suppressing the exposure of the operator WP.

[0052] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and may be modified without changing the gist described in each claim.

[0053] For example, the layout shown in FIG. 1 is merely an example and may be changed as appropriate.

[0054] In the above embodiment, the first shielding member is the fixed side and the second shielding member is the moving side. However, the first shielding member may be the moving side and the second shielding member may be the moving side. Further, although the second shielding member has moved in a direction perpendicular to the beam axis in the horizontal direction on the floor surface, the moving mode and the moving direction are not limited thereto. For example, a moving mode such as manual or electric drive may be adopted.

Description of Reference Numerals

[0055] 1... Neutron capture therapy device, 5... Target, 21... First shielding member, 22... Second shielding member, 25... Shielding member, 40... Transfer mechanism, 45... Cart.

Claims

1. A neutron capture therapy device for irradiating a subject with neutron rays, comprising: a target that generates the neutron rays by irradiating a particle beam; a plurality of shielding members that cover the periphery of the target and shield radiation from the target; and a neutron capture therapy device, wherein the target and at least one of the shielding members are configured to be movable to an exchange work position for performing an exchange operation of the target.

2. The neutron capture therapy device according to claim 1, wherein the target is movable to the exchange work position together with the shielding member.

3. The neutron capture therapy device according to claim 1, wherein the target has a horizontal movement component and is movable to the exchange work position.

4. There is a work position where an operator who performs the replacement of the target works, The work position is provided at a position where the shielding member arranged at the exchange work position is interposed between the target arranged at the exchange work position. The neutron capture therapy device according to claim 1.

5. further comprising a target duct for holding the target, the plurality of shielding members include a first shielding member whose position is fixed and a second shielding member that moves to the exchange work position, The first shielding member and the second shielding member are provided with a transfer mechanism for switching the target duct from a state supported by the first shielding member to a state supported by the second shielding member. The neutron capture therapy device according to claim 1.

6. A target replacement method for a neutron capture therapy device that irradiates a subject with neutron rays, the method comprising replacing a target that generates the neutron rays by irradiating a particle beam, The neutron capture therapy device is a plurality of shielding members that cover the periphery of the target and shield radiation from the target; a target duct for holding the target; and moving the target, the target duct, and at least one of the shielding members to an exchange work position for performing an exchange operation of the target; placing the target duct and the target on a cart and transporting them from the exchange work position. A target replacement method.

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