Particle beam therapy device and mobile bed

Abstract

The objective is to provide a particle beam therapy device and a mobile bed that can stably drive the mobile bed. [Solution] The movable floor 35 performs either a first movement in one direction D1 in the direction of movement, or a second movement in the other direction D2. As a result, the movable floor 35 can move to both sides in the direction of movement in accordance with the movement of the irradiation unit 3. Here, in both the first and second movements, the length of the portion of the movable floor 35 that moves by traction is longer than the length of the portion of the movable floor 35 that moves by extrusion. That is, regardless of whether the movable floor 35 moves to the direction D1 or D2, the portion of the movable floor 35 that moves by traction, which is more stable, can be made longer than the portion that moves by extrusion.

Description

Technical Field

[0001] The present invention relates to a particle beam therapy apparatus and a moving bed.

Background Art

[0002] Conventionally, a particle beam therapy apparatus described in Patent Document 1 below is known. This particle beam therapy apparatus includes a gantry that mounts an irradiation unit for irradiating a particle beam and rotates around a treatment table, and a moving bed that is disposed inside the gantry, partitions the treatment room, and moves in a circular orbit around the treatment table. The circular orbit of the moving bed is composed of a curved portion along the circumferential direction of the rotation of the gantry and a horizontal portion along the floor of the treatment room. Since the irradiation unit rotates in a circular orbit while the moving bed moves in a non-circular circular orbit as described above, the gap generated between the moving bed and the irradiation unit varies depending on the rotational position of the irradiation unit.

[0003] The moving bed is rotationally driven along a track provided on a fixed ring by a drive rod connected to the gantry. The moving bed is configured by arranging a plurality of bed members along a circular orbit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, while the annular track is formed by a continuous, smooth curve, the movable floor, which is made up of multiple floor members connected together, is arranged in a polygonal shape along the annular track. Therefore, the length of the movable floor over 360° expands and contracts by several millimeters depending on the rotational phase. For this reason, it is necessary to provide some play (a non-connected section that is not connected to the adjacent floor member) at some point along the annular track of the movable floor. Such play may be provided at a position 180° from the drive floor member to which the drive rod is connected (see Figure 9(a)). In this case, when the drive floor member moves, half of the movable floor is subjected to a driving force that pulls it towards the drive floor member, and the other half is subjected to a driving force that pushes it towards the drive floor member. This play may be provided between the drive floor member and the adjacent floor member (see Figure 9(b)). In this case, when the drive floor member moves to one side, the entire portion of the movable floor is subjected to a driving force that pulls it towards the drive floor member. Also, when the drive floor member moves to the other side, the entire portion of the movable floor is subjected to a driving force that pushes it towards the drive floor member. However, the driving force used to push out the floor components is prone to causing jams in the circular track, making it difficult to perform stably. Therefore, there was a need to drive the moving floor stably.

[0006] Therefore, the present invention aims to provide a particle beam therapy apparatus and a mobile bed that can stably drive a mobile bed. [Means for solving the problem]

[0007] The particle beam therapy apparatus of the present invention comprises: an irradiation unit that irradiates an object to be irradiated with a particle beam and is rotatable around the object to be irradiated; and a movable floor that extends on an annular trajectory surrounding the object to be irradiated, having a curved portion extending along the rotational circumferential direction of the irradiation unit and a horizontal portion connected to the curved portion, and is movable on the annular trajectory according to the position of the irradiation unit, wherein the movable floor performs either a first movement in one direction in the direction of movement or a second movement in the other direction, and in both the first and second movements, the length of the portion of the movable floor that moves by traction is longer than the length of the portion of the movable floor that moves by extrusion.

[0008] In this particle beam therapy device, the moving bed performs either a first movement, moving in one direction in the direction of movement, or a second movement, moving in the other direction. This allows the moving bed to move on both sides in the direction of movement in accordance with the movement of the irradiation unit. Here, in both the first and second movements, the length of the portion of the moving bed that moves by traction is longer than the length of the portion of the moving bed that moves by extrusion. In other words, regardless of which side the moving bed moves, the portion of the moving bed that moves by traction, which is more stable, can be made longer than the portion that moves by extrusion. As a result, the moving bed can be driven stably.

[0009] The movable floor comprises a plurality of floor members and connecting fittings that connect the floor members to each other. The floor members are connected to the connecting fittings via shafts. The movable floor has a first connection point and a second connection point at any position on the circular track. In the first movement, the shaft is connected at the first connection point so as to pull the connecting fitting, and the connection between the shaft and the connecting fitting is released at the second connection point. In the second movement, the shaft is connected at the second connection point so as to pull the connecting fitting, and the connection between the shaft and the connecting fitting is released at the first connection point. In this case, the portion of the movable floor between the first and second connection points is driven by traction from the first connection point side during the first movement, and by traction from the second connection point side during the second movement.

[0010] In the first and second connection sections, the connecting fitting may have an elongated hole through which the shaft is inserted. Depending on which side of the direction of movement the shaft is moving, the shaft can be connected to the connecting fitting by contacting the end of the elongated hole, and the connection can be released by making it non-contact. Therefore, a simple configuration in which only the through-hole of the connecting fitting is an elongated hole makes it possible to drive the moving floor stably.

[0011] At the first and second connection points, the connection to the connecting fitting may be released by electrically driving the shaft. In this case, the connection and release of the shaft to the connecting fitting can be easily controlled.

[0012] Among multiple floor members, one floor member may have a first connection and a second connection. In this case, the length of the portion to which the driving force is applied by traction can be increased.

[0013] The movable floor comprises multiple floor members and connecting fittings that connect the floor members to each other. The floor members are connected to the connecting fittings via shafts, and at least one of the movable floors may have an elongated hole through which the shafts are inserted. Depending on which side of the direction of movement the shaft is moving, the shaft can be connected to the connecting fitting by contacting the end of the elongated hole, and the connection can be released by making it non-contact. Therefore, the movable floor can be driven stably with a simple configuration that only requires the through-hole of the connecting fitting to be an elongated hole.

[0014] The movable floor is provided at multiple locations on the circular track and further includes drive gears for driving the movable floor. The movable floor has multiple floor members and connecting fittings for connecting the floor members, and at any point on the movable floor, an unconnected section is formed that is not connected by the connecting fittings. In this case, by switching the drive gear that drives the movable floor according to the rotation phase, it is possible to control the length of the section to which traction driving force is applied.

[0015] The movable floor of the present invention is provided in a particle beam therapy apparatus having an irradiation unit that irradiates an object to be irradiated with a particle beam and is capable of rotating around the object to be irradiated. The movable floor has a curved portion extending along the rotational circumferential direction of the irradiation unit and a horizontal portion connected to the curved portion, and extends on an annular track surrounding the object to be irradiated. The movable floor is capable of moving on the annular track according to the position of the irradiation unit, and performs either a first movement moving to one side in the direction of movement, or a second movement moving to the other side. In both the first and second movements, the length of the portion of the movable floor that moves by traction is longer than the length of the portion of the movable floor that moves by extrusion.

[0016] According to this moving bed, the same operations and effects as those of the above-described particle beam therapy apparatus can be obtained.

Advantages of the Invention

[0017] According to the present invention, a particle beam therapy apparatus capable of stably driving a moving bed and a moving bed can be provided.

Brief Description of the Drawings

[0018] [Figure 1] It is a diagram showing a charged particle beam therapy system incorporating a charged particle beam therapy apparatus according to this embodiment. [Figure 2] It is a perspective view showing a state of viewing the charged particle beam therapy apparatus from the treatment room side. [Figure 3] It is a cross-sectional view of the charged particle beam therapy apparatus taken along a vertical cross-section including the axis of rotation. [Figure 4] It is a cross-sectional view of the charged particle beam therapy apparatus taken along a vertical cross-section orthogonal to the axis of rotation. [Figure 5] It is an enlarged view seen from the treatment room side showing the configuration around the drive bed member. [Figure 6] It is an enlarged view seen from the treatment room side showing the configuration around the drive bed member. [Figure 7] It is an enlarged view seen from the treatment room side showing the configuration around the drive bed member. [Figure 8] It is a diagram for explaining the operation of the moving bed. [Figure 9] It is a diagram for explaining the operation of the moving bed according to the comparative example. [Figure 10] It is a diagram for explaining a modification example. [Figure 11] It is a diagram for explaining a modification example. [Figure 12] It is a diagram for explaining a modification example. [Figure 13] It is a diagram for explaining a modification example.

Modes for Carrying Out the Invention

[0019] The embodiments of the particle beam therapy apparatus according to the present invention will be described in detail below with reference to the drawings. Note that in some cases, features may be exaggerated in the drawings, and the dimensional ratios and shapes of the parts of the particle beam therapy apparatus shown in the drawings do not necessarily match the actual apparatus, nor do they necessarily match between the drawings. As shown in Figure 1, the particle beam therapy apparatus 100 of this embodiment is incorporated into a charged particle beam therapy system 103 (for example, a proton beam therapy system). The particle beam therapy apparatus 100 is a device that treats a lesion (for example, a tumor, etc.) inside a patient P (the irradiated body) by irradiating it with a charged particle beam. Here, the charged particle beam is, for example, a proton beam, a heavy ion beam, etc.

[0020] The charged particle beam therapy system 103 comprises an accelerator 105 that accelerates charged particles and emits a charged particle beam, an irradiation unit 3 that irradiates the patient P with the charged particle beam, a rotating gantry 13 that rotates the irradiation unit 3 around a horizontal rotation axis A around the treatment table 7 on which the patient P lies, and a transport line 107 that connects the accelerator 105 and the irradiation unit 3 and transports the charged particle beam from the accelerator 105 to the irradiation unit 3. Of these, the particle beam therapy device 100 comprises a part of the transport line 107, the rotating gantry 13, and the irradiation unit 3. The transport line 107 has a plurality of quadrupole electromagnets 113 for focusing the charged particle beam and a plurality of bending magnets 115 for bending the charged particle beam. Furthermore, the transport line 107 has a plurality of ESSs (not shown) that selectively pass charged particle beams of a desired energy width from the incoming charged particle beam.

[0021] Figure 2 is a perspective view of the particle beam therapy device 100 as seen from the treatment room. Figure 3 is a cross-sectional view of the particle beam therapy device 100 taken in a vertical section including the rotation axis, and Figure 4 is a schematic cross-sectional view of the particle beam therapy device 100 taken in a vertical section perpendicular to the rotation axis.

[0022] As shown in Figures 2 to 4, the rotating gantry 13 is cylindrical with rotation axis A as its cylindrical axis. The axial length of the rotating gantry 13 is, for example, 8 m, and its diameter is, for example, 6 m. Note that the rotating gantry 13 is not limited to a rotatable cylindrical shape, but may also have a frame that can swing 180° around rotation axis A. An irradiation unit 3 is positioned on the inner circumferential surface side of the cylindrical rotating gantry 13, and the irradiation unit 3 is fixed to the rotating gantry 13 via a predetermined support frame. As the rotating gantry 13 rotates around rotation axis A, the irradiation unit 3 rotates and moves around rotation axis A in a position where the direction of emission of the charged particle beam is directed radially inward of the rotating gantry 13. That is, the irradiation unit 3 can rotate and move around the patient P, who is positioned on rotation axis A on the treatment table 7, and can irradiate the patient P with the charged particle beam from various directions. Note that the treatment table 7 is fixed to the building structure 27 via an arm for moving the treatment table 7 within the treatment room.

[0023] To rotate the rotating gantry 13 as described above, two roller devices 29 are provided below the rotating gantry 13, positioned on the floor surface of the building 27, as shown in Figure 3. The outer circumferential surfaces of both axial ends of the rotating gantry 13 are in contact with the roller devices 29, and the rotational driving force around the rotation axis A is applied to the rotating gantry 13 when the roller devices 29 are driven by a motor (not shown). In addition, the rotation of the rotating gantry 13 is stopped by a brake device (not shown) of the roller devices 29.

[0024] The treatment room 31 in which the above-mentioned treatment table 7 is placed extends from within the building 27 to a portion of the area inside the rotating gantry 13. As shown in Figures 2 to 4, a movable floor 35 is provided inside the rotating gantry 13 to separate the treatment room 31 from the machine room 33 inside the rotating gantry 13. As shown in Figure 4, the movable floor 35 extends in an annular shape over the entire annular track 37 that surrounds the rotation axis A, and also spreads out in a strip shape with a predetermined width (for example, about 2m wide) in the direction of the rotation axis A. The movable floor 35 moves along the annular track 37 as the rotating gantry 13 rotates. The annular track 37, when viewed from a line of sight parallel to the rotation axis A (as shown in Figure 4), has a curved portion 37a that extends along the rotational circumferential direction of the rotating gantry 13 and the irradiation unit 3, and a horizontal portion 37b that extends horizontally to connect the two lower ends of the curved portion 37a, and as a whole it has a tunnel shape. The space inside this circular track 37 is part of the treatment room 31, and patients P and treatment staff involved in treatment can move around within this space.

[0025] As shown in Figure 3, the building 27 cantileveredly supports a movable floor 35 that extends into the area inside the rotating gantry 13, and is also provided with a fixing ring 38 that guides the movement of the movable floor 35. The fixing ring 38 is provided in a tunnel shape along the annular track 37 when viewed from a line of sight parallel to the rotation axis A, and holds the movable floor 35 in a state that allows it to move on the annular track 37. As shown in Figure 4, the movable floor 35 is composed of a number of floor members 39 arranged and laid out on the annular track 37, and each floor member 39 is slidably held by the fixing ring 38. The floor members 39 are long, plate-like members that extend in the direction of the rotation axis A. Adjacent floor members 39 may be connected so that they can rotate relative to each other around an axis parallel to the rotation axis A. With this structure, the movable floor 35 is bendable between the floor members 39 and can move on the annular track 37 while curving and deforming to conform to the shape of the annular track 37.

[0026] The movable floor 35 has sufficient rigidity and strength to adequately support a person's weight while being cantilevered by the fixing ring 38. As shown in Figure 3, the horizontal portion 37b of the annular track 37 is located along the floor 31a of the treatment room 31 in the building 27, and the upper surface of the movable floor 35 in the horizontal portion 37b is almost flush with the floor 31a. Therefore, patients P and treatment staff involved in treatment can walk on the floor 31a and the movable floor 35 extending from the floor 31a within the treatment room 31.

[0027] The mechanism for moving the movable floor 35 on the annular track 37 is as follows. As shown in Figures 3 and 4, the movable floor 35 is connected to the rotating gantry 13 via a drive rod 41 that extends in the radial direction of rotation. One end of the drive rod 41 is connected to one of the drive floor members 39A of the floor members 39 that make up the movable floor 35 via a hinge portion 42a having a hinge axis parallel to the rotation axis A. The other end of the drive rod 41 is held so as to be slidable in the radial direction of rotation by a rod holding portion 42b of the rotating gantry 13. The rod holding portion 42b has the structure of, for example, an LM guide.

[0028] With this mechanism, when the rotating gantry 13 rotates around the rotation axis A by the roller device 29, the driving force in the rotational circumferential direction is transmitted to the moving floor 35 via the drive rod 41, and the moving floor 35 moves along the annular track 37 to follow the rotating gantry 13. At this time, the distance between the hinge portion 42a and the rod holding portion 42b changes as the moving floor 35 moves, but this distance change is absorbed by the other end of the drive rod 41 sliding radially at the rod holding portion 42b (see Figure 4(b)). At this time, the drive rod 41 can slide radially through the rotating gantry 13, and for this reason, the rotating gantry 13 is provided with space for inserting the sliding drive rod 41.

[0029] The movable floor 35 performs either a first movement toward one direction D1 in the direction of movement MD, or a second movement toward the other direction D2 in the direction of movement (see Figure 4). In this embodiment, a clockwise rotation constitutes the first movement toward direction D1, and a counterclockwise rotation constitutes the second movement toward direction D2.

[0030] As shown in Figure 3, in addition to the movable floor 35 described above, a vertical partition wall 45 is provided inside the rotating gantry 13 to separate the treatment room 31 and the machine room 33 in the direction of the rotation axis A. The vertical partition wall 45 is positioned vertically perpendicular to the rotation axis A, along the rear edge of the movable floor 35 as viewed from inside the treatment room 31. For example, the vertical partition wall 45 is a disc shape with a diameter slightly smaller than the inner diameter of the rotating gantry 13 and its center located at the position of the rotation axis A. For example, a motor (not shown) that rotates the vertical partition wall 45 is fixed to the rotating gantry 13, and this motor allows the vertical partition wall 45 to rotate around the rotation axis A relative to the rotating gantry 13. When the rotating gantry 13 rotates due to the roller device 29, the motor rotates the vertical partition wall 45 in the opposite direction to counteract this rotation, so that the vertical partition wall 45 remains stationary relative to the treatment room 31. Therefore, the vertical partition wall 45 functions as a stationary vertical wall separating the treatment room 31 from the machine room 33.

[0031] Furthermore, as shown in Figures 1 and 3, the rotating gantry 13 supports a portion of the transport line 107 on the downstream side (referred to as "transport line 107a"). Transport line 107a includes, for example, a quadrupole electromagnet 113 for focusing the charged particle beam and a bending magnet 115 for curving the charged particle beam. The downstream end of transport line 107a is connected to the irradiation unit 3, and the upstream end of transport line 107a is connected to the upstream portion of transport line 107 by a rotation mechanism (not shown). Transport line 107a rotates around the rotation axis A as the rotating gantry 13 rotates.

[0032] As shown in Figures 2 to 4, the irradiation unit 3 protrudes from the machine room 33 side across the annular track 37 into the treatment room 31. The irradiation unit 3 has an irradiation nozzle 51 that irradiates the charged particle beam sent from the transport line 107a toward the patient P on the treatment table 7. As shown in Figure 4, the position of the irradiation nozzle 51 on the annular track 37 and the direction of the charged particle beam B irradiated from the irradiation nozzle 51 are adjusted by the movement of the moving bed 35 along the annular track 37.

[0033] In this embodiment, in both the first and second movements, the length of the portion of the movable floor 35 that moves by traction is longer than the length of the portion of the movable floor 35 that moves by extrusion. The detailed configuration of the movable floor 35 for performing such movement will be described in detail with reference to Figures 5 to 7. Figures 5 to 7 are enlarged views from the treatment room 31 side showing the configuration around the drive floor member 39A. Figure 5 shows the movable floor 35 in the stopped movement state. In the stopped movement state in Figure 5, the size of the gap between the drive floor member 39A and the adjacent floor members 39 on both sides is assumed to be equal. Figure 6 shows the movable floor 35 in the first movement state moving toward direction D1. Figure 7 shows the movable floor 35 in the second movement state moving toward direction D2.

[0034] The movable floor 35 has a plurality of floor members 39 and connecting fittings 60 that connect the floor members 39 to each other. The connecting fittings 60 connect pairs of adjacent floor members 39. Each floor member 39 has an end 39a on the direction D1 side and an end 39b on the direction D2 side. In this case, the end 39a of the floor member 39 is connected to the end 39b of the adjacent floor member 39 on the direction D1 side via the connecting fittings 60. The end 39b of the floor member 39 is connected to the end 39a of the adjacent floor member 39 on the direction D2 side via the connecting fittings 60. Note that the connecting fittings 60 provided on the end 39a of the drive floor member 39A are referred to as connecting fittings 60B. The connecting fittings 60 provided on the end 39b of the drive floor member 39A are referred to as connecting fittings 60A.

[0035] The end 39a of the floor member 39 is connected to the end 60b of the connecting fitting 60 on the orientation D2 side via the shaft portion 61. A through hole 62B is formed in the end 60b of the connecting fitting 60. The shaft portion 61 is inserted into the hole in the end 39a of the floor member 39, passing through the through hole 62B. The end 39b of the floor member 39 is connected to the end 60a of the connecting fitting 60 on the orientation D1 side via the shaft portion 61. A through hole 62A is formed in the end 60a of the connecting fitting 60. The shaft portion 61 is inserted into the hole in the end 39b of the floor member 39, passing through the through hole 62A. The through holes 62A and 62B of the connecting fitting 60 connected to floor members 39 other than the drive floor member 39A have a circular shape with approximately the same diameter as the outer diameter of the shaft portion 61. The through holes 62A and 62B are allowed to have a small amount of play relative to the shaft portion 61, but they are not allowed to have a gap large enough to switch the connection state depending on the direction of movement of the movable floor 35, as is the case with the elongated holes described later.

[0036] The movable floor 35 has a first connecting portion 63A and a second connecting portion 63B at any position on the annular track 37. The first connecting portion 63A is provided at the end 39b of the drive floor member 39A on the direction D2 side. The first connecting portion 63A is formed by inserting the shaft portion 61 into the end 39b of the drive floor member 39A through the through hole 62A of the end 60a of the connecting fitting 60A. The second connecting portion 63B is provided at the end 39a of the drive floor member 39A on the direction D1 side. The second connecting portion 63B is provided at the end 39a of the drive floor member 39A on the direction D1 side. The second connecting portion 63B is formed by inserting the shaft portion 61 into the end 39a of the drive floor member 39A through the through hole 62A of the end 60b of the connecting fitting 60A.

[0037] In the first movement, the shaft portion 61 is connected at the first connection portion 63A so as to pull the connecting fitting 60A, and the connection between the shaft portion 61 and the connecting fitting 60B is released at the second connection portion 63B. In this case, as the drive floor member 39A moves toward direction D1, the drive floor member 39A pulls the other floor member 39 toward direction D2 via the shaft portion 61 and the connecting fitting 60A. In the second movement, the shaft portion 61 is connected at the second connection portion 63B so as to pull the connecting fitting 60B, and the connection between the shaft portion 61 and the connecting fitting 60A is released at the first connection portion 63A. In this case, as the drive floor member 39A moves toward direction D2, the drive floor member 39A pulls the other floor member 39 toward direction D1 via the shaft portion 61 and the connecting fitting 60B.

[0038] In this embodiment, the connecting fittings 60A and 60B in the first connecting portion 63A and the second connecting portion 63B have elongated holes 64 through which the shaft portion 61 is inserted. That is, the through holes 62A and 62B become elongated holes 64. The elongated holes 64 extend so as to have a longitudinal direction in the direction of movement MD. The elongated holes 64 have an end 62a on the direction D1 side and an end 62b on the direction D2 side. The ends 62a and 62b have a semicircular shape with a diameter approximately the same as the outer diameter of the shaft portion 61. In the stopped movement state shown in Figure 5, the shaft portion 61 inserted into the elongated hole 64 of the connecting fitting 60A is positioned spaced apart from the ends 64a and 64b on both sides. The distance between the shaft portion 61 and end 64a is shorter than the distance between the shaft portion 61 and end 64b. The shaft portion 61, inserted into the elongated hole 64 of the connecting fitting 60B, is positioned spaced apart from the ends 64a and 64b on both sides. The distance between the shaft portion 61 and the end 64b is shorter than the distance between the shaft portion 61 and the end 64a.

[0039] As shown in Figure 6, when the drive floor member 39A moves toward direction D1 in the first movement, the shaft portion 61 inserted into the connecting fittings 60A and 60B also moves toward direction D1 within the elongated hole 64. The shaft portion 61 of connecting fitting 60A comes into contact with the end portion 64a of the elongated hole 64 toward direction D1. As a result, at the first connection portion 63A, the shaft portion 61 is connected in such a way that it pulls the connecting fitting 60A. On the other hand, the shaft portion 61 of connecting fitting 60B does not come into contact with the end portion 64a of the elongated hole 64 toward direction D1. As a result, at the second connection portion 63B, the connection between the shaft portion 61 and the connecting fitting 60B remains disconnected.

[0040] As shown in Figure 7, when the drive floor member 39A moves toward direction D2 during the second movement, the shaft portion 61 inserted into the connecting fittings 60A and 60B also moves toward direction D2 within the elongated hole 64. The shaft portion 61 of connecting fitting 60B comes into contact with the end portion 64b of the elongated hole 64 toward direction D2. As a result, at the second connection portion 63B, the shaft portion 61 is connected in such a way that it pulls the connecting fitting 60B. On the other hand, the shaft portion 61 of connecting fitting 60A does not come into contact with the end portion 64b of the elongated hole 64 toward direction D2. As a result, at the first connection portion 63A, the connection between the shaft portion 61 and the connecting fitting 60A remains disconnected.

[0041] Next, the operation and effects of the particle beam therapy apparatus 100 and the mobile bed 35 according to this embodiment will be described.

[0042] First, with reference to Figure 9, the movable floor 135 relating to the comparative example will be described. While the annular track 37 is formed by a continuous smooth curve, the movable floor 135, which is formed by connecting multiple floor members 39, is arranged in a polygonal shape along the annular track 37. Therefore, the length of the movable floor for 360° expands and contracts by several millimeters depending on the rotation phase. For this reason, it is necessary to provide some play (a non-connecting portion 70 that is not connected to the adjacent floor member) at some point on the annular track 37 of the movable floor 135. Such a non-connecting portion 70 may be provided at a position 180° from the drive floor member 39A to which the drive rod 41 is connected (see Figure 9(a)). In this case, when the drive floor member 39A moves, a driving force F1 is applied to half of the movable floor 135 E1 so as to be pulled by the drive floor member 39A, and a driving force F2 is applied to the other half E2 so as to be pushed by the drive floor member 39A. Section E1 is the region between the drive floor member 39A and the non-connecting section 70 in the right half. Section E2 is the region between the drive floor member 39A and the non-connecting section 70 in the left half. The non-connecting section 70 may also be provided between the drive floor member 39A and the adjacent floor member 39 (see Figure 9(b)). In this case, when the drive floor member 39A moves to one side of direction D1, a driving force F1 is applied to the entire portion of the movable floor 135, causing it to be pulled by the drive floor member 39A. When the drive floor member 39A moves to the direction D2, a driving force F2 is applied to the entire portion of the movable floor 135, causing it to be pushed by the drive floor member 39A. However, the driving force F2 that pushes the floor member 39 is prone to causing jamming in the annular track 37, and it is difficult to perform this stably. Therefore, it was required to drive the movable floor 35 stably.

[0043] In contrast, in the particle beam therapy apparatus 100 according to this embodiment, the movable bed 35 performs either a first movement, moving in one direction D1 in the direction of movement, or a second movement, moving in the other direction D2. As a result, the movable bed 35 can move to both sides in the direction of movement in accordance with the movement of the irradiation unit 3. Here, in both the first and second movements, the length of the portion of the movable bed 35 that moves by traction is longer than the length of the portion of the movable bed 35 that moves by extrusion. That is, regardless of whether the movable bed 35 moves to the direction D1 or D2, the portion of the movable bed 35 that moves by traction, which is more stable, can be made longer than the portion that moves by extrusion. As a result, the movable bed 35 can be driven stably.

[0044] The movable floor 35 has a plurality of floor members 39 and connecting fittings 60 that connect the floor members 39 to each other. The floor members 39 are connected to the connecting fittings 60 via shafts 61. The movable floor 35 has a first connecting part 63A and a second connecting part 63B at any position on the ring track 37. In the first movement, the first connecting part 63A is connected so that the shaft 61 pulls the connecting fitting 60, and the connection between the shaft 61 and the connecting fitting 60 is released at the second connecting part 63B. In the second movement, the second connecting part 63B is connected so that the shaft 61 pulls the connecting fitting 60, and the connection between the shaft 61 and the connecting fitting 60 is released at the first connecting part 63A. In this case, the portion of the movable bed 35 between the first connection part 63A and the second connection part 63B (the entire circumference of the movable bed 35) is subjected to a driving force F1 by traction from the first connection part 63A side during the first movement (see Figure 8(a)), and is subjected to a driving force F1 by traction from the second connection part 63B side during the second movement (Figure 8(b)). Thus, in the particle beam therapy apparatus 100 according to this embodiment, no portion of the movable bed 35 moves by extrusion drive occurs in either direction D1 or D2. Therefore, the movable bed 35 can have a longer portion that moves by traction drive, which is more stable than the portion that moves by extrusion drive.

[0045] In the first connection portion 63A and the second connection portion 63B, the connecting fittings 60A and 60B may have elongated holes 64 through which the shaft portion 61 is inserted. Depending on which side of the direction of movement the shaft portion 61 moves, it can be connected to the connecting fitting 60 by contacting the ends 64a and 64b of the elongated holes 64, and the connection can be released by making it non-contact. Therefore, the movable floor 35 can be driven stably with a simple configuration that only requires replacing the through holes 62A and 62B of the connecting fitting 60 with elongated holes 64.

[0046] Of the multiple floor members 39, one floor member 39 (here, the drive floor member 39A) may have a first connection part 63A and a second connection part 63B. In this case, the length of the portion to which the driving force F1 by traction is applied can be increased. When the drive floor member 39A has both connection parts 63A and 63B, the driving force F1 by traction can be applied to the entire area of ​​the movable floor 35 during movement on both sides of directions D1 and D2.

[0047] The movable floor 35 comprises a plurality of floor members 39 and connecting fittings 60 that connect the floor members 39 to each other. The floor members 39 are connected to the connecting fittings 60 via shafts 61, and the movable floor 35 may have an elongated hole 64 at at least one location through which the shafts 61 are inserted. Depending on which side of the direction of movement the shafts 61 are moving, the shafts 61 can be connected to the connecting fittings 60 by contacting the ends 64a and 64b of the elongated hole 64, and the connection can be released by making them non-contact. Therefore, the movable floor 35 can be driven stably with a simple configuration that only requires the through holes 62A and 62B of the connecting fittings 60 to be elongated holes 64.

[0048] The movable floor 35 according to this embodiment is provided in a particle beam therapy apparatus 100 having an irradiation unit 3 that irradiates an object to be irradiated with a particle beam and is rotatably movable around the object to be irradiated. The movable floor 35 has a curved portion 37a that extends along the rotational circumferential direction of the irradiation unit 3 and a horizontal portion 37b connected to the curved portion 37a, and extends on an annular track 37 that surrounds the object to be irradiated. The movable floor 35 is movable on the annular track 37 according to the position of the irradiation unit 3, and performs either a first movement moving in one direction D1 in the direction of movement, or a second movement moving in the other direction D2. In both the first and second movements, the length of the portion of the movable floor 35 that moves by traction is longer than the length of the portion of the movable floor 35 that moves by extrusion.

[0049] With this movable bed 35, the same actions and effects as the particle beam therapy device 100 described above can be obtained.

[0050] The present invention is not limited to the embodiments described above.

[0051] For example, the configuration shown in Figure 10 may be adopted. In the particle beam therapy apparatus 100 shown in Figure 10, the connection between the shaft portion 61 and the connecting fittings 60A and 60B may be released by electrically driving the shaft portion 61 at the first connection portion 63A and the second connection portion 63B. In this case, the connection and release of the shaft portion 61 to the connecting fittings 60 can be easily controlled. As shown in Figure 10, the first connection portion 63A allows the electrically driven shaft portion 61 to be inserted into and removed from the through hole 62A of the connecting fitting 60A. The second connection portion 63B allows the electrically driven shaft portion 61 to be inserted into and removed from the through hole 62B of the connecting fitting 60B. When the shaft portion 61 is inserted into the through holes 62A and 62B, the connecting fittings 60A and 60B can be connected to the drive floor member 39A. When the shaft portion 61 is removed from the through holes 62A and 62B, the connection between the drive floor member 39A and the connecting fittings 60A and 60B is released. The shaft portion 61 reciprocates within the through holes 62A and 62B by an electric drive unit 71 provided on the drive floor member 39A. The through holes 62A and 62B, like the other through holes 62, have a circular shape with approximately the same diameter as the shaft portion 61. The electrically driven shaft portion 61 may have a tapered tip to facilitate fitting with the through holes 62A and 62B.

[0052] For example, the configuration shown in Figures 11 to 13 may be adopted. The movable floor 35 shown in Figures 11 to 13 is provided at multiple locations (three locations in this case) on the ring track 37 and further comprises drive gears 75A, 75B, and 75C for driving the movable floor 35. Drive gear 75A is provided at a position corresponding to the left end of the horizontal section 37b. Drive gear 75B is provided at a position corresponding to the right end of the horizontal section 37b. Drive gear 75C is provided at a position corresponding to the center of the curved section 37a. The movable floor 35 has multiple floor members 39 and connecting fittings 60 for connecting the floor members 39 to each other, and at any position of the movable floor 35 an unconnected section 70 that is not connected by the connecting fittings 60 may be formed. In this case, by switching the drive gears 75A, 75B, and 75C that are driven according to the rotational phase of the movable floor 35, it is possible to control the length of the section to which driving force is applied by traction.

[0053] Next, the operation of the movable floor 35 using the drive gears 75A, 75B, and 75C will be explained with reference to Figures 11 to 13. Here, the movable floor 35 is assumed to move toward direction D1. As shown in Figure 11(a), the operation is assumed to start from a state where the unconnected portion 70 is positioned corresponding to the drive gear 75A. The drive gears 75B and 75C, other than the drive gear 75A, are separated from the movable floor 35. When the drive gear 75A is driven, a driving force F1 due to traction acts on almost the entire circumference of the movable floor 35. As shown in Figure 11(b), when a part of the movable floor 35 is fed out to the drive gear 75A, a driving force F2 due to extrusion acts on the short region between the unconnected portion 70 and the drive gear 75A.

[0054] As shown in Figure 12(a), when the unconnected portion 70 reaches the position corresponding to the drive gear 75C, driving by the drive gear 75C begins, and the drive gears 75A and 75B other than the drive gear 75C move away from the moving floor 35. When the drive gear 75C is driven, a driving force F1 due to traction acts on almost the entire circumference of the moving floor 35. As shown in Figure 12(b), when a part of the moving floor 35 is fed out to the drive gear 75C, a driving force F2 due to extrusion acts on the short region between the unconnected portion 70 and the drive gear 75C.

[0055] As shown in Figure 13(a), when the unconnected portion 70 reaches the position corresponding to the drive gear 75B, driving by the drive gear 75B begins, and the other drive gears 75A and 75C move away from the moving floor 35. When the drive gear 75B is driven, a traction-driven force F1 acts on almost the entire circumference of the moving floor 35. As shown in Figure 13(b), when a part of the moving floor 35 is fed by the drive gear 75B, a push-driven force F2 acts on the short region between the unconnected portion 70 and the drive gear 75B.

[0056] As shown in Figures 11 to 13, regardless of the rotational phase of the unconnected section 70, the length of the portion of the movable floor 35 subjected to the traction-driven force F1 is longer than the length of the portion subjected to the extrusion-driven force F2. This relationship is also true when the movable floor 35 moves toward direction D2.

[0057] In addition, in the above-described embodiment, both the first and second connection portions were provided on a single drive floor member. However, the present invention is not limited to this configuration, and within the scope of the present invention, the first and second connection portions may be provided on different floor members. In this case, the drive floor member does not necessarily have to be provided with either the first or second connection portion. It doesn't have to be the drive floor section. [Explanation of Symbols]

[0058] 3...Irradiation unit, 35...Moving floor, 37...Annular track, 37a...Curved section, 37b...Horizontal section, 39...Floor member, 60...Connecting fitting, 61...Shaft section, 62A, 62B...Through hole, 63A...First connection part, 63B...Second connection part, 64...Slotted hole, 75A, 75B, 75C...Drive gear, 100...Particle beam therapy device, P...Patient (irradiated body).

Claims

1. An irradiation unit that irradiates an object to be irradiated with a particle beam and is capable of rotating around the object to be irradiated, A movable floor is provided, which has a curved portion extending along the rotational circumferential direction of the irradiation unit and a horizontal portion connected to the curved portion, and which extends along the annular track surrounding the object to be irradiated, and which is movable along the annular track according to the position of the irradiation unit, The moving floor performs either a first movement in one direction in the direction of movement, or a second movement in the other direction. A particle beam therapy apparatus in which, in both the first movement and the second movement, the length of the portion of the moving bed that moves by traction is longer than the length of the portion of the moving bed that moves by extrusion.

2. The movable floor comprises a plurality of floor members and connecting fittings that connect the floor members to each other. The floor member is connected to the connecting fitting via the shaft portion. The movable floor has a first connecting portion and a second connecting portion at any position on the circular track. In the first movement, the shaft is connected at the first connection point so as to pull the connecting fitting, and the connection between the shaft and the connecting fitting is released at the second connection point. The particle beam therapy apparatus according to claim 1, wherein in the second movement, the shaft is connected at the second connection point so as to pull the connecting fitting, and the connection between the shaft and the connecting fitting is released at the first connection point.

3. The particle beam therapy apparatus according to claim 2, wherein the connecting fitting has an elongated hole through which the shaft portion is inserted in the first connecting portion and the second connecting portion.

4. The particle beam therapy apparatus according to claim 2, wherein the connection between the connecting fitting and the shaft portion is released by electrically driving the shaft portion at the first connecting portion and the second connecting portion.

5. The particle beam therapy apparatus according to claim 2, wherein one of the multiple floor members has the first connecting portion and the second connecting portion.

6. The movable floor comprises a plurality of floor members and connecting fittings that connect the floor members to each other. The floor member is connected to the connecting fitting via the shaft portion. The particle beam therapy apparatus according to claim 1, wherein the movable bed has an elongated hole through which the shaft portion is inserted at least at one location.

7. The following are provided at multiple locations on the aforementioned ring track, and further comprising drive gears for driving the moving floor, The movable floor comprises a plurality of floor members and connecting fittings that connect the floor members to each other. The particle beam therapy apparatus according to claim 1, wherein a non-connected portion is formed at any position of the movable floor that is not connected by the connecting fitting.

8. A movable bed provided in a particle beam therapy apparatus having an irradiation unit that irradiates an object to be irradiated with a particle beam and is capable of rotating around the object to be irradiated, It has a curved portion extending along the rotational circumferential direction of the irradiation unit and a horizontal portion connected to the curved portion, and extends along the annular track surrounding the object to be irradiated, and is movable along the annular track according to the position of the irradiation unit. Perform either a first movement to one side in the direction of movement, or a second movement to the other side. A movable floor in which, in both the first movement and the second movement, the length of the portion of the movable floor that moves by traction is longer than the length of the portion of the movable floor that moves by extrusion.

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