Particle beam therapy device

Abstract

To provide a particle beam treatment apparatus which can cover a gap between an irradiation unit and a movable bed so as to be able to secure the safety.SOLUTION: A charged particle beam irradiation apparatus 100 comprises: an irradiation unit 3 which has an irradiation nozzle 51 that irradiates a patient P with a particle beam and is rotationally movable around the patient P; a movable bed 35 which has a curved portion 37a and a horizontal portion 37b extending along the rotation peripheral direction of the irradiation unit 3, extends on an annular track 37 surrounding the patient P and is movable on the annular track 37; a movable cover 59 which is supported so as to be rotatable with respect to the irradiation unit 3 or movable bed 35 and covers a gap between the irradiation unit 3 and the movable bed 35; and an adjustment mechanism 63 which can adjust the rotation position of the movable cover 59 according to the position of the irradiation unit 3 such that the gap between the movable cover 59 and the movable bed 35 is covered.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a particle beam therapy system. [Background technology]

[0002] Conventionally, particle beam therapy devices described in the following Patent Documents 1 to 3 are known. These particle beam therapy devices include a gantry equipped with an irradiation unit that irradiates particle beams and rotates around the treatment table, and a movable floor that is disposed inside the gantry, separates the treatment room, and moves around the treatment table on a circular orbit. The circular orbit of the movable floor is composed of a curved portion that follows the circumferential direction of the gantry's rotation and a horizontal portion that follows the floor of the treatment room. While the irradiation unit rotates on a circular orbit, the movable floor moves on the above-mentioned non-circular circular orbit, so the gap between the movable floor and the irradiation unit varies depending on the rotational position of the irradiation unit.

[0003] In order to cover the gap that occurs between the movable bed and the irradiation unit as described above, the particle beam therapy devices of Patent Documents 1 and 2 listed below have a movable bed slidably connected to the side of the irradiation unit. With this mechanism, instead of covering the gap on the side of the irradiation unit, a gap in the movable bed occurs at another location on the circular orbit. Since the width of this gap varies depending on the rotational position of the irradiation unit, the gap is covered with a retractable cover with a variable width. Similarly, the particle beam therapy device of Patent Document 3 listed below also employs a retractable cover to cover the gap between the movable bed and the irradiation unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-156263 [Patent Document 2] Japanese Patent Application Publication No. 2017-12374 [Patent Document 3] Japanese Patent Application Publication No. 2019-201730 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because the above-mentioned retractable cover must be a relatively soft material that can be retracted, it is not necessarily capable of adequately supporting a person's weight. Therefore, when a gap is located in a horizontal portion of the circular track of the movable bed, even if the gap is covered with a retractable cover, it cannot be said that a person can walk safely on the movable bed. Therefore, in the particle beam therapy devices of Patent Documents 1 to 3, it cannot be said that the gap in the movable bed is covered in a manner that ensures safety. In view of this problem, an object of the present invention is to provide a particle beam therapy device that enables the gap between the irradiation unit and the movable bed to be covered in a manner that ensures safety. [Means for solving the problem]

[0006] The particle beam therapy device of the present invention comprises an irradiation unit having an irradiation nozzle that irradiates the irradiated body with particle beams and that is capable of rotating around the irradiated body; a movable floor that has a curved portion extending along the circumferential direction of the irradiation unit and a horizontal portion connected to the curved portion, extends on a circular orbit that surrounds the irradiated body and is movable on the circular orbit depending on the position of the irradiation unit; a movable cover that is rotatably supported on the irradiation unit or the movable floor and covers the gap between the irradiation unit and the movable floor; and an adjustment mechanism that adjusts the rotational position of the movable cover depending on the position of the irradiation unit so that the gap between the movable cover and the movable floor is covered.

[0007] The movable cover is supported rotatably relative to the irradiation unit, and the adjustment mechanism has a first support part provided on the irradiation unit and pivotally supporting a part of the movable cover, and a second support part provided on the moving floor and supporting another part of the movable cover, and the second support part may allow displacement of the movable cover in a straight line connecting the second support part and the first support part.

[0008] The adjustment mechanism may have a guide rail provided on the movable cover and extending on a straight line connecting the first support part and the second support part, and the second support part may include a roller that rolls on the guide rail. The movable cover may be rotatably supported with respect to the irradiation part and may be capable of crossing the circular track and protruding into an area outside the circular track. The movable floor may have a plurality of floor members arranged on the circular track in the moving direction of the movable floor, and may be bendable between the floor members. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a particle beam therapy system that can cover the gap between the irradiation unit and the movable floor in a manner that ensures safety. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing a charged particle beam therapy system incorporating a charged particle beam irradiation device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing the charged particle beam irradiation device as seen from the treatment room side. [Figure 3] 1 is a cross-sectional view of a charged particle beam irradiation device taken along a vertical cross section including a rotation axis. [Figure 4] 1 is a cross-sectional view of a charged particle beam irradiation device taken along a vertical cross section perpendicular to a rotation axis. [Figure 5] FIG. 2 is a perspective view showing the charged particle beam irradiation device with the movable floor removed and viewed from the machine room side. [Figure 6] FIG. 6 is a perspective view showing the positional relationship between the movable floor and the irradiation unit in FIG. 5 as viewed from the machine room side. [Figure 7] FIG. 10 is a perspective view showing the vicinity of the irradiation unit protruding into the treatment room as viewed from the treatment room side. [Figure 8] 7A is a perspective view showing the movable cover, and FIG. 7B is a view including the roller as seen from the direction of arrow VIIIb in FIG. [Figure 9] FIG. 5 is a cross-sectional view showing a state in which the irradiation unit has rotated and moved diagonally below the treatment table from the state in FIG. 4. [Figure 10] FIG. 10 is a cross-sectional view of a charged particle beam irradiation device including a modified example of the adjustment mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of a particle beam therapy device according to the present invention will be described in detail with reference to the drawings. Note that in each drawing, features may be depicted in an exaggerated manner, and the dimensional ratios and shapes of each part of the particle beam therapy device in the drawings do not necessarily correspond to the actual objects, and do not necessarily correspond between drawings. As shown in FIG. 1, a charged particle beam irradiation device 100 (particle beam therapy device) according to this embodiment is incorporated into a charged particle beam therapy system 103 (e.g., a proton beam therapy system). The charged particle beam irradiation device 100 is a device that irradiates a lesion (e.g., a tumor, etc.) inside a patient P (irradiated body) with a charged particle beam to perform therapy. Here, the charged particle beam may be, for example, a proton beam, a heavy particle beam, etc.

[0012] The charged particle beam therapy system 103 includes an accelerator 105 that accelerates charged particles and emits a charged particle beam, an irradiation unit 3 that irradiates a patient P with the charged particle beam, a rotating gantry 13 that rotates the irradiation unit 3 about a horizontal rotation axis A around a 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 charged particle beam irradiation device 100 includes a portion of the transport line 107, the rotating gantry 13, and the irradiation unit 3. The transport line 107 includes a plurality of quadrupole electromagnets 113 for converging the charged particle beam and a plurality of bending magnets 115 for curving the charged particle beam. The transport line 107 also includes a plurality of ESSs (not shown) that selectively pass charged particle beams of a desired energy width from among the transmitted charged particle beams.

[0013] Fig. 2 is a perspective view showing the charged particle beam irradiation device 100 as seen from the treatment room side. Fig. 3 is a cross-sectional view of the charged particle beam irradiation device 100 taken along a vertical cross section including the rotation axis, and Fig. 4 is a cross-sectional view of the charged particle beam irradiation device 100 taken along a vertical cross section perpendicular to the rotation axis.

[0014] As shown in FIGS. 2 to 4 , the rotating gantry 13 has a cylindrical shape with a rotation axis A as its cylindrical axis. The axial length of the rotating gantry 13 is, for example, 8 m, and the diameter is, for example, 6 m. The rotating gantry 13 is not limited to a rotatable cylindrical shape, and may have a frame that can swing 180° around the rotation axis A. The irradiation unit 3 is disposed on the cylindrical inner surface of the 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 the rotation axis A, the irradiation unit 3 rotates around the rotation axis A with the emission direction of the charged particle beam facing radially inward of the rotating gantry 13. In other words, the irradiation unit 3 can rotate around the patient P placed on the rotation axis A on the treatment table 7, and can irradiate the patient P with the charged particle beam from various directions. The treatment table 7 is fixed to the building 27 via an arm that moves the treatment table 7 within the treatment room.

[0015] In order to rotate the rotating gantry 13 as described above, roller devices 29 are provided below the rotating gantry 13 at two locations on the floor of the building 27, as shown in Fig. 3. The outer peripheral surfaces of both axial ends of the rotating gantry 13 abut against the roller devices 29, and when the roller devices 29 are driven by a motor (not shown), a rotational driving force about the rotation axis A is applied to the rotating gantry 13. In addition, the rotation of the rotating gantry 13 is stopped by a brake device (not shown) of the roller devices 29.

[0016] The treatment room 31 in which the treatment couch 7 is placed is disposed from inside the building 27 to a portion of the area inside the rotating gantry 13. As shown in FIGS. 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. FIG. 5 is a perspective view showing the movable floor 35 removed and viewed from the machine room 33 side. As shown in FIGS. 4 and 5, the movable floor 35 extends in a circular shape over the entire circular track 37 that circularly surrounds the rotation axis A, and spreads out in a strip shape with a predetermined width (for example, a width of about 2 m) in the direction of the rotation axis A. The movable floor 35 moves on the circular track 37 as the rotating gantry 13 rotates. When viewed from a line of sight parallel to the rotation axis A (as shown in Figure 4), the circular track 37 has a curved portion 37a extending along the circumferential direction of rotation of the rotating gantry 13 and the irradiation unit 3, and a horizontal portion 37b extending horizontally so as to connect the two lower ends of the curved portion 37a, and has an overall tunnel-like shape. The space inside this circular track 37 is part of the treatment room 31, and patient P involved in treatment, treatment staff, etc. can move back and forth within this space.

[0017] As shown in FIG. 3 , the building 27 is provided with a fixed ring 38 that cantilevers the movable floor 35 that extends into the area inside the rotating gantry 13 and guides the movement of the movable floor 35. The fixed ring 38 is tunnel-shaped and extends along the circular track 37 when viewed parallel to the rotation axis A. The fixed ring 38 holds the movable floor 35 in a state that allows it to move on the circular track 37. As shown in FIG. 5 , the movable floor 35 is composed of a number of floor members 39 arranged and laid out on the circular track 37, and each floor member 39 is slidably held by the fixed ring 38. The floor members 39 are elongated plate-like members extending in the direction of the rotation axis A. Adjacent floor members 39 may be connected to each other so that they can rotate relatively 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 circular track 37 while curving and deforming as a whole to follow the shape of the circular track 37.

[0018] The movable floor 35 has sufficient rigidity and strength to support the weight of a person while being cantilevered on the fixed ring 38. As shown in Fig. 3, the horizontal portion 37b of the circular 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 at the horizontal portion 37b is positioned almost flush with the floor 31a. Therefore, the patient P involved in treatment, treatment staff, etc. can walk on the floor 31a and the movable floor 35 extended from the floor 31a within the treatment room 31.

[0019] The mechanism for moving the movable floor 35 on the circular track 37 is as follows. As shown in FIGS. 3 and 4, the movable floor 35 is connected to the rotating gantry 13 via a drive rod 41 extending in the radial direction of rotation. One end of the drive rod 41 is connected to one 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 by a rod holding portion 42b of the rotating gantry 13 so as to be slidable in the radial direction of rotation. The rod holding portion 42b has, for example, an LM guide structure.

[0020] With this mechanism, when the rotating gantry 13 rotates around the rotation axis A by the roller device 29, the driving force in the circumferential direction of rotation is also transmitted to the movable floor 35 via the drive rod 41, and the movable floor 35 moves on the circular track 37 to follow the rotating gantry 13. At this time, the distance between the hinge portion 42a and the rod holding portion 42b varies due to the movement of the movable floor 35, but this variation in distance is absorbed by the other end of the drive rod 41 sliding radially on the rod holding portion 42b. At this time, the drive rod 41 is able to slide radially through the rotating gantry 13, and for this reason the rotating gantry 13 has a space for the sliding drive rod 41 to pass through.

[0021] In addition to the movable floor 35 described above, a vertical partition wall 45 is provided inside the rotating gantry 13, separating the treatment room 31 and the machine room 33 in the direction of the rotation axis A. The vertical partition wall 45 is disposed in a vertical position perpendicular to the rotation axis A, along the far edge of the movable floor 35 as viewed from inside the treatment room 31. For example, the vertical partition wall 45 is disk-shaped with a diameter slightly smaller than the inner diameter of the rotating gantry 13 and a center 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 the motor can rotate the vertical partition wall 45 about the rotation axis A relative to the rotating gantry 13. When the rotating gantry 13 is rotated by the roller device 29, the motor rotates the vertical partition wall 45 in the opposite direction to offset the rotation, thereby keeping the vertical partition wall 45 stationary with respect to the treatment room 31. Therefore, the vertical partition wall 45 functions as a stationary vertical wall for separating the treatment room 31 from the machine room 33 .

[0022] 1 and 3, a downstream portion of the transport line 107 (referred to as "transport line 107a") is supported on the rotating gantry 13. The transport line 107a includes, for example, a quadrupole electromagnet 113 that focuses the charged particle beam and a bending magnet 115 that curves the charged particle beam. The downstream end of the transport line 107a is connected to the irradiation unit 3, and the upstream end of the transport line 107a is connected to the upstream portion of the transport line 107 by a rotation mechanism (not shown). The transport line 107a rotates around the rotation axis A as the rotating gantry 13 rotates.

[0023] As shown in FIGS. 2 to 4, the irradiation unit 3 protrudes from the machine room 33 side into the treatment room 31 across the circular track 37. The irradiation unit 3 has an irradiation nozzle 51 that irradiates the patient P on the treatment couch 7 with a charged particle beam sent from the transport line 107a. The irradiation unit 3 further has a pair of X-ray tubes 53 that are provided on either side of the irradiation nozzle 51 in the circumferential direction of rotation, and a support frame (not shown) that fixes the irradiation nozzle 51 and the X-ray tube 53 to the rotating gantry 13. The X-ray tube 53 is part of a CT device (not shown), which is used for CT imaging of the patient P. The CT image obtained by CT imaging identifies the position of a lesion or the like in the patient P, and the patient P is positioned on the treatment couch 7.

[0024] As shown in FIG. 5, the movable floor 35 is provided with an irradiation unit insertion port 36 so that the irradiation unit 3 can protrude into the treatment room 31. The many floor members 39 constituting the movable floor 35 include two types: one with a long length in the direction of the rotation axis A (referred to as "floor member 39t") and one with a short length (referred to as "floor member 39s"). The movable floor 35 has two areas: an area where the floor members 39t are continuously arranged, and an area where the floor members 39s are continuously arranged. In the area where the floor members 39s are continuously arranged, the floor member 39s is located on the near side as viewed from inside the treatment room 31, and the aforementioned irradiation unit insertion port 36 is formed between the floor member 39s and the vertical partition wall 45 (FIG. 3) at the far side. The irradiation unit 3 is inserted into the irradiation unit insertion port 36 and protrudes into the treatment room 31.

[0025] Fig. 6 is a perspective view showing the positional relationship between the movable floor 35 in Fig. 5 and the irradiation unit 3 inserted into the irradiation unit insertion opening 36, as viewed from the machine room 33 side. Fig. 7 is a perspective view showing the vicinity of the irradiation unit 3 protruding into the treatment room 31, as viewed from the treatment room 31 side. As shown in Figs. 4, 6, and 7, the irradiation unit 3 protrudes into the treatment room 31 from the irradiation unit insertion opening 36, and the irradiation unit 3 is provided with an irradiation unit cover 55 for covering the irradiation nozzle 51 and the X-ray tube 53. As shown in Fig. 7, the main parts of the irradiation nozzle 51 and the X-ray tube 53 are covered with the irradiation unit cover 55 so that they cannot be seen from the treatment room 31 side.

[0026] The irradiation unit cover 55 includes a fixed cover 57 whose position is fixed relative to the irradiation nozzle 51 and the X-ray tube 53, and a movable cover 59 that is movable relative to the irradiation nozzle 51 and the X-ray tube 53. The fixed cover 57 includes an irradiation nozzle cover 57a that covers the front and bottom sides of the irradiation nozzle 51 when viewed from inside the treatment room 31, and a curved X-ray tube cover 57b that covers the periphery of the X-ray tube 53. The irradiation nozzle cover 57a and the X-ray tube cover 57b are connected below the movable cover 59. The fixed cover 57 may be fixed to, for example, the support frame (not shown) that fixes the irradiation nozzle 51 and the X-ray tube 53 to the rotating gantry 13. A gap is generated above the irradiation nozzle cover 57a and between the irradiation nozzle cover 57a and the curved portion 37a of the circular track 37, but this gap is closed by, for example, an end face of the support frame.

[0027] The movable cover 59 is positioned adjacent to the edge 36a (FIGS. 4 and 5) in the movement direction of the irradiation unit insertion port 36 of the movable floor 35. One end of the movable cover 59 is pivotally supported by the irradiation unit 3. A gap J is formed between the movable cover 59 and the edge 36a in the movement direction of the movable floor 35. Specifically, a parallel cover portion 59b (described later) of the movable cover 59 faces the edge 36a of the movable floor 35 with the gap J therebetween. As shown in FIG. 4, the edge 36a is present both in front and behind the rotation direction as viewed from the irradiation unit 3. Accordingly, a pair of movable covers 59 are provided symmetrically in front and behind the irradiation unit 3, sandwiching the irradiation unit 3 therebetween. FIG. 8(a) is a perspective view showing the movable cover 59. Note that FIG. 8(a) shows one of the pair of movable covers 59, but the other movable cover 59 has a shape symmetrical to that of FIG. 8(a), and therefore is not shown or described here.

[0028] As shown in FIG. 8( a), the movable cover 59 has an L-shaped cross section as a whole and includes an orthogonal cover portion 59a located in a plane perpendicular to the rotation axis A and a parallel cover portion 59b located in a plane parallel to the rotation axis A. The parallel cover portion 59b has a rectangular notch 59c formed therein to avoid interference with the X-ray tube cover 57b of the fixed cover 57. One end of the movable cover 59 is pivotally supported by the irradiation nozzle 51 at a hinge portion 64, and the hinge portion 64 has a hinge axis parallel to the rotation axis A. That is, the movable cover 59 is supported by the irradiation nozzle 51 at one end so as to be rotatable about the hinge portion 64 when viewed from a line of sight parallel to the rotation axis A (as viewed in FIG. 4). As shown in FIG. 4, the hinge portion 64 is disposed on the irradiation nozzle 51 at a location that is always located within the inner region of the annular orbit 37 regardless of the rotation position of the irradiation unit 3. The other end of the movable cover 59 reaches a position outside the annular track 37 , and a part of the other end protrudes outside the annular track 37 .

[0029] The rotating gantry 13 is provided with an adjustment mechanism 63 that can adjust the rotational position of the movable cover 59 in response to the rotational movement of the irradiation unit 3 so that the gap J is always covered regardless of the rotational position of the irradiation unit 3. Note that "the gap J is covered" does not necessarily mean a state in which the gap J is zero, but rather a state in which the gap J is small enough to prevent part or all of the body of a person in the treatment room 31 (e.g., patient P, treatment staff, equipment maintenance staff, etc.) from entering the gap J. Furthermore, the size of the gap J adjusted by the adjustment mechanism 63 may be even smaller than the above. For example, the size of the gap J adjusted by the adjustment mechanism 63 may satisfy the condition that the machine room 33 is always invisible through the gap J from inside the treatment room 31 regardless of the rotational position of the irradiation unit 3. The adjustment mechanism 63 has the aforementioned hinge unit 64 (first support unit) that is provided on the irradiation nozzle 51 of the irradiation unit 3 and pivotally supports one end of the movable cover 59, and an outer end support unit 65 (second support unit) that is provided on the moving floor 35 and supports other parts of the movable cover 59.

[0030] The outer end support portion 65 constitutes a mechanism that allows displacement of the movable cover 59 in the direction of a line connecting the outer end support portion 65 and the hinge portion 64. The outer end support portion 65 also allows rotation of the movable cover 59 around the outer end support portion 65. As a specific example of such a mechanism, the adjustment mechanism 63 has a guide rail 67 (FIG. 8(a)) with a U-shaped cross section that is provided on the movable cover 59. The guide rail 67 extends on a line connecting the hinge portion 64 and the outer end support portion 65. Two guide rails 67 are provided on both edges of the parallel cover portion 59b, respectively, and extend parallel to a direction perpendicular to the rotation axis A. The hinge portion 64 is located at one end of the guide rails 67. The outer end support portion 65 includes rollers 69 (FIG. 8(b)) that engage with the guide rails 67 and roll on the guide rails 67.

[0031] FIG. 8(b) is an arrow view including the rollers 69, as viewed from the direction of arrow VIIIb in FIG. 6. As shown in FIG. 8(b), the outer end support portion 65 has a bracket 71 fixed to a floor member 39t that forms the edge portion 36a of the movable floor 35. The bracket 71 extends in the direction of the rotation axis A at a position where the parallel cover portion 59b is sandwiched between the bracket 71 and the edge portion 36a. The outer end support portion 65 has the rollers 69 provided at both ends of the bracket 71 in the direction of the rotation axis A. In this embodiment, as shown in FIG. 4, when viewed in a line of sight parallel to the rotation axis A, the two rollers 69 are located slightly outside the annular track 37 and immediately adjacent to the edge portion 36a of the irradiation unit insertion opening 36. Each roller 69 is fitted inside a corresponding guide rail 67 and rolls within the guide rail 67, allowing the movable cover 59 to be displaced relative to the rollers 69 in the extension direction of the guide rail 67.

[0032] The effects of the charged particle beam irradiation device 100 including the rotating gantry 13 and irradiation unit 3 described above will be described. As described above, the irradiation unit 3 rotates in a circular orbit as the rotating gantry 13 rotates. Meanwhile, the movable floor 35 moves on a non-circular annular orbit 37 as the rotating gantry 13 rotates. As described above, if the movable cover 59 were fixed to the irradiation unit 3, the size of the gap J would vary with the rotation of the irradiation unit 3 and the movable floor 35, as can be understood geometrically, due to the fact that the movement trajectories of the irradiation unit 3 and the rotating gantry 13 do not coincide. In particular, in this embodiment, the irradiation unit 3 is configured to cross the annular orbit 37 of the movable floor 35 and protrude into the treatment room 31, so the variation in the size of the gap J is significant.

[0033] In contrast, in the charged particle beam irradiation device 100, the movable cover 59 is rotatably supported with respect to the irradiation unit 3, and the rotation position of the movable cover 59 is adjusted by the adjustment mechanism 63 according to the rotation position of the irradiation unit 3, so that the gap J is always covered. For example, as shown in Fig. 9, when the irradiation unit 3 moves diagonally downward from the treatment table 7, one of the movable covers 59 (indicated by the symbol 59A in the figure) changes its rotation position counterclockwise relative to the irradiation unit 3, and is displaced so as to significantly protrude outside the circular track 37 (i.e., displaced so as to significantly intrude into the machine room 33). By changing the rotation position of the movable cover 59 in this way, the gap J is covered.

[0034] Furthermore, because the movable cover 59 is configured to cover the gap J by changing its rotational position relative to the irradiation unit 3, the movable cover 59 itself does not need to deform to match the size of the gap J. Therefore, the movable cover 59 can be made of a hard, inflexible material, and, for example, the movable cover 59 can be provided with rigidity and strength sufficient to support a person's weight. For example, unlike the retractable covers of Patent Documents 1 to 3, the movable cover 59 may be made of metal. In this case, as shown in FIG. 9, for example, when the movable cover 59A is positioned near the horizontal portion 37b of the circular track 37, even if a patient P or a medical staff member on the movable floor 35 steps on the movable cover 59A, the movable cover 59A can safely support the weight of the patient P or the medical staff member. In other words, since the patient P or the medical staff member can safely walk on the movable floor 35, it can be said that the gap between the irradiation unit 3 and the movable floor 35 is covered by the movable cover 59A, ensuring safety.

[0035] Furthermore, if the size of the gap J adjusted by the adjustment mechanism 63 satisfies the condition that the machine room 33 is always invisible through the gap J from inside the treatment room 31 regardless of the rotational position of the irradiation unit 3, the mechanical structure of the machine room 33 can be made invisible to the patient P undergoing treatment through the hidden gap J.

[0036] Furthermore, if a method of covering gap J with a retractable cover were adopted, tension would need to be applied to the retractable cover, which could make the retractable cover more susceptible to damage and require more frequent maintenance. In contrast, no tension needs to be applied to movable cover 59, which means that the cover has a longer lifespan than a method using a retractable cover.

[0037] Moreover, in the adjustment mechanism 63, one end of the movable cover 59 is pivotally supported on the irradiation nozzle 51 via a hinge portion 64, and another portion of the movable cover 59 is supported by an outer end support portion 65 in the vicinity of the edge portion 36a, and the outer end support portion 65 constitutes a mechanism that allows displacement of the movable cover 59 in the direction of a line connecting the outer end support portion 65 and the hinge portion 64. According to this mechanism, the movable cover 59 automatically changes its rotation position and always passes through the outer end support portion 65 in the vicinity of the edge portion 36a, so that the gap J is automatically covered by the movable cover 59.

[0038] As a result, the gap J between the parallel cover portion 59b and the edge portion 36a is always kept covered regardless of the rotational position of the irradiation unit 3. In this way, since the movable cover 59 rotates automatically, there is no need for a power source for driving the movable cover 59 or a control unit for controlling the rotation angle of the movable cover 59. Furthermore, the adjustment mechanism 63 is made up of simple mechanical elements such as a hinge portion 64 that pivotally supports the movable cover 59, a guide rail 67 with a U-shaped cross section provided on the movable cover 59, and a roller 69 that rolls on the guide rail 67, so that the adjustment mechanism 63 can be made up of general-purpose parts.

[0039] Furthermore, the movable floor 35 is composed of floor members 39t, 39s arranged in the direction of movement. In the area where the floor members 39s are continuously arranged, the floor member 39s of the movable floor 35 is present only on the front side as viewed from inside the treatment room 31, and the irradiation unit 3 protruding from the irradiation unit insertion port 36 is present on the back side. Therefore, when the irradiation unit 3 is located on the horizontal portion 37b of the circular track 37, the patient P and treatment staff in the treatment room 31 can walk on the movable floor 35 by stepping on the floor member 39s present on the front side of the irradiation unit 3.

[0040] Furthermore, the movable cover 59 is supported by a hinge portion 64 located in the inner region of the annular track 37 and can protrude across the annular track 37 to the outer region of the annular track 37 (towards the machine room 33). Therefore, even when the distance between the hinge portion 64 and the roller 69 is at its greatest, the protruding portion can be pulled into the inner region of the annular track 37, and the gap J can be covered by the movable cover 59.

[0041] Furthermore, the movable floor 35 has floor members 39 arranged and laid out in the direction of movement of the movable floor 35 on the circular track 37, and is bendable between the floor members 39. With this configuration, the movable floor 35 can be deformed to follow the tunnel shape of the circular track 37, and by forming the movable floor 35 with a large number of floor members 39 that fill the circular track 37 without excess or deficiency, it is possible to ensure the safety of the patient P, treatment staff, and others walking on the movable floor 35.

[0042] The present invention can be implemented in various forms, including the above-described embodiment, with various modifications and improvements based on the knowledge of those skilled in the art. It is also possible to configure modified examples by utilizing the technical matters described in the above-described embodiment. The configurations of the respective embodiments may be used in appropriate combination.

[0043] For example, in the above-described embodiment, the adjustment mechanism 63 rotates the movable cover 59 without a power source. However, the adjustment mechanism 63 may also have a power source for rotating the movable cover 59. As an example, as shown in FIG. 10 , the adjustment mechanism 63 may include a stepping motor 75 that rotates the movable cover 59 about the hinge portion 64 relative to the irradiation nozzle 51, and a control circuit (not shown) that controls the rotation angle of the stepping motor 75. The control circuit controls the rotation angle of the stepping motor 75 to adjust the rotation position of the movable cover 59 so that the parallel cover portion 59b of the movable cover 59 is always positioned immediately adjacent to the edge portion 36a ( FIG. 5 ) of the movable floor 35. In other words, the control circuit controls the stepping motor 75 to adjust the rotation position of the movable cover 59, so that the gap J is always covered. In this case, the outer end support portion 65 including the guide rail 67 and the roller 69 may be omitted. If the outer end support part 65 including the guide rails 67 and rollers 69 is omitted and a stepping motor 75 and control circuit are used, the movable cover 59 does not apply force to the movable floor 35, thereby increasing the operational stability of the movable floor 35. Also, if the stepping motor 75 and control circuit are used in addition to the outer end support part 65 including the guide rails 67 and rollers 69, the operational stability of the movable cover 59 and the movable floor 35 is improved.

[0044] Furthermore, in the outer end support portion 65 in the above embodiment, a mechanism combining the guide rails 67 and rollers 69 is employed as a mechanism for allowing displacement of the movable cover 59 in the linear direction connecting the outer end support portion 65 and the hinge portion 64, but the outer end support portion 65 is not limited to this mechanism. For example, a mechanism may be employed in which the outer end support portion 65 slidably connects the movable cover 59 and the moving floor 35 via an LM guide.

[0045] Furthermore, in the above-described embodiment, the movable cover 59 is rotatably supported with respect to the irradiation unit 3, but the object for which the movable cover 59 is rotatably supported is not limited to the irradiation unit 3. For example, the movable cover 59 may be rotatably supported with respect to the moving floor 35 so as to cover the gap between the movable cover 59 and the moving floor 35, and the adjustment mechanism 63 may have a power source (for example, a motor) for rotating the movable cover 59.

[0046] The size of the gap J may also vary depending on the position of the irradiation unit 3. In this case, however, the size of the gap J is to vary within a range that is small enough to prevent part or all of a human body in the treatment room 31 from entering the gap. Alternatively, the size of the gap J may vary within a range that satisfies the condition that the machine room 33 is always not visible through the gap J from inside the treatment room 31 regardless of the rotational position of the irradiation unit 3. [Explanation of symbols]

[0047] 3...irradiation unit, 31...treatment room, 35...movable floor, 37...annular track, 37a...curved portion, 37b...horizontal portion, 39...floor member, 51...irradiation nozzle, 59...movable cover, 64...hinge portion (first support portion), 63...adjustment mechanism, 65...outer end support portion (second support portion), 67...guide rail, 69...roller, 100...charged particle beam irradiation device (particle beam therapy device), J...gap, P...patient (irradiated body).

Claims

1. an irradiation unit having an irradiation nozzle for irradiating a particle beam onto an object to be irradiated and capable of rotating around the object to be irradiated; a movable bed that has a curved portion extending along the circumferential direction of rotation of the irradiation unit and a horizontal portion connected to the curved portion, extends on a circular track surrounding the irradiated body, and is movable on the circular track according to the position of the irradiation unit; a movable cover that is rotatably supported with respect to the irradiation unit or the moving floor, covers a gap between the irradiation unit and the moving floor, and is made of an inflexible member; an adjustment mechanism that adjusts the rotation position of the movable cover in accordance with the position of the irradiation unit so that a gap between the movable cover and the movable floor is covered.

2. the movable cover is supported rotatably with respect to the irradiation unit, The adjustment mechanism includes: a first support part that is provided on the irradiation part and pivotally supports a part of the movable cover; and a second support part that is provided on the moving floor and supports another part of the movable cover, The particle beam therapy system according to claim 1 , wherein the second support portion allows the movable cover to be displaced in a direction of a straight line connecting the second support portion and the first support portion.

3. the adjustment mechanism has a guide rail that is provided on the movable cover and extends on a straight line connecting the first support portion and the second support portion, The particle beam therapy system according to claim 2 , wherein the second support portion engages with the guide rail and allows the movable cover to be displaced in the extending direction of the guide rail.

4. 4. The particle beam therapy device according to claim 1, wherein the movable cover is rotatably supported relative to the irradiation unit and is capable of crossing the annular orbit and protruding into an area outside the annular orbit.

5. The moving bed is 5. The particle beam therapy device according to claim 1, further comprising a plurality of floor members arranged on the circular orbit in the direction of movement of the movable floor, the floor members being bendable between each other.

6. An irradiation unit having an irradiation nozzle that irradiates a particle beam onto an irradiated object and that is capable of rotating around the irradiated object; a movable bed that has a curved portion extending along the circumferential direction of rotation of the irradiation unit and a horizontal portion connected to the curved portion, extends on a circular track surrounding the irradiated body, and is movable on the circular track according to the position of the irradiation unit; a movable cover that is rotatably supported with respect to the irradiation unit or the moving floor and covers a gap between the irradiation unit and the moving floor; an adjustment mechanism that adjusts the rotation position of the movable cover in accordance with the position of the irradiation unit so that the gap between the movable cover and the moving floor is covered; the movable cover is supported rotatably with respect to the irradiation unit, The adjustment mechanism includes: a first support part that is provided on the irradiation part and pivotally supports a part of the movable cover; and a second support part that is provided on the moving floor and supports another part of the movable cover, the second support portion allows displacement of the movable cover in a linear direction connecting the second support portion and the first support portion, the adjustment mechanism has a guide rail that is provided on the movable cover and extends on a straight line connecting the first support portion and the second support portion, The second support portion includes a roller that rolls on the guide rail.

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