JP2007236776A - Primary body diaphragm and radiotherapeutic instrument with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique to define a field of irradiation with radiation irradiated to a testee, to freely deform the field of irradiation across its periphery, and to ensure cost reductions while maintaining the shape of the field of irradiation coinciding with the shape of an affected part. <P>SOLUTION: The radiotherapeutic instrument has a doughnut-shaped flexible deforming body 61 which is filled with a powder to absorb radiation and has a through-hole made along the axis of exposure and defines the field of irradiation by deforming the cross-sectional shape of the through-hole 62. The field of irradiation becomes freely deformable across the periphery. A possibility of freely deforming the entire periphery of the field of irradiation simplifies an arrangement structure by arranging driving mechanisms such as arms 63 or the like to deform the cross-sectional shape of the through-hole and permits cost reductions. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for defining an irradiation field of radiation applied to a subject.

  Conventionally, radiation treatment aiming at treatment is widely performed by exposing radiation to an affected area such as cancer or tumor, thereby destroying tissue cells of the affected area or preventing division. In this radiotherapy, it is important to accurately irradiate the affected part with radiation in order to minimize damage to normal tissues around the affected part and to effectively irradiate the affected part with radiation.

  Therefore, the generated radiation is narrowed down by the original body throttling device so that the irradiation field becomes the same as the shape of the affected part. The original diaphragm device is composed of a plurality of leaf blocks called multi-leaf collimators.

  The leaf block is made of a material that absorbs radiation, such as tungsten or molybdenum. The original diaphragm device moves the leaf block to a region where radiation exposure is prevented to define the radiation field in a predetermined shape (see, for example, “Patent Document 1” and “Patent Document 2”).

  FIG. 6 is an external view showing a conventional original diaphragm device. As shown in FIG. 6, the original aperture device 100 is installed on an exposure axis of radiation irradiated from the radiation source S. This original diaphragm device 100 includes a multi-leaf collimator 101.

  The multi-leaf collimator 101 includes plate-like leaf blocks 101A and 101B that face each other across a radiation exposure axis. The leaf blocks 101 </ b> A and 101 </ b> B have a tapered cross section and an arch shape with a short circumferential side surface.

  The leaf blocks 101A and 101B are positioned within the radiation emission range to narrow the radiation range, thereby defining an irradiation field F that matches the shape of the affected part and preventing unnecessary irradiation to tissues other than the affected part.

  FIG. 7 is a perspective view of a conventional multi-leaf collimator 101. As shown in FIG. 7, in the multi-leaf collimator 101, a plurality of pairs of leaf blocks 101A and 101B are arranged in parallel so that their side surfaces are in contact with each other or close to each other.

  The pair of leaf blocks 101 </ b> A and 101 </ b> B moves toward or away from each other independently along the same arc trajectory centered on the radiation source S. An appropriate irradiation field F as the whole multi-leaf collimator 101 is defined by the approach or separation of the pair of leaf blocks 101A and 101B.

  The multi-leaf collimator 101 has a drive mechanism corresponding to each of the leaf blocks 101A and 101B so that the leaf blocks 101A and 101B can be moved independently and the pair of leaf blocks 101A and 101B can be moved independently. 101C is connected and provided. There are as many drive mechanisms 101C as the number of leaf blocks 101A and 101B.

JP 2003-79754 A Japanese Patent Laid-Open No. 7-255718

  In the original diaphragm device provided with such a multi-leaf collimator 101, the movement of the leaf blocks 101A and 101B is limited only in the approaching or separating direction, so that the shape of the defined irradiation field F is the shape of the leaf blocks 101A and 101B. It cannot be deformed in the parallel direction.

  Therefore, in the case where the shape of the affected area is a shape having irregularities such as a hypotenuse part and a curved part in the parallel direction of the leaf blocks 101A and 101B, such as a shape in which irregularities such as a star shape exist all around, for example, F could not be matched to the shape of the affected part.

  Further, in recent years, since the original diaphragm device provided with the multi-leaf collimator 101 is required to define the irradiation field F that more closely matches the shape of the affected part, the leaf blocks 101A and 101B have recently been made thinner. This is because the irradiation field F is made closer to the shape of the affected part by reducing the level difference between the oblique side and the curved part.

  At the same time, in order to maintain the maximum area of the irradiation field F, the number of leaf blocks 101A and 101B tends to increase in inverse proportion to the thickness reduction. Along with this, the number of drive mechanisms 101C required for the number of leaf blocks 101A and 101B arranged in the original diaphragm device 100 is also increasing.

  Therefore, the increased drive mechanism 101C is installed behind the leaf blocks 101A and 101B, and it is necessary to arrange these drive mechanisms 101C in a limited space. Therefore, the arrangement structure of the drive mechanisms 101C is complicated, The cost was high.

  The present invention has been made in view of the above-described problems, and its purpose relates to a technique for defining an irradiation field of radiation applied to a subject, and a technique for freely deforming the irradiation field all around. It is to provide. Another object of the present invention is to provide a technique for reducing the cost while maintaining the irradiation field shape that matches the shape of the affected part, with respect to the technique for defining the radiation field irradiated to the subject.

  The invention according to claim 1 for solving the above-mentioned problem is an original diaphragm device that defines an irradiation field of radiation, and is filled with a powder that absorbs radiation, and along the axis of radiation exposure. It is characterized by comprising a donut-shaped flexible deformable body having a drilled through-hole and a shape control unit for deforming the cross-sectional shape of the through-hole.

  The flexible deformation body may be a bag body and sealed with a powder that absorbs radiation (corresponding to the invention of claim 2).

  The outer shell of the bag may be filled with a powder that absorbs radiation (corresponding to the invention of claim 3).

  The flexible deformation body may be made of rubber (corresponding to the invention of claim 4).

  The shape control unit includes a plurality of arms that are arranged transversely from the side surface of the flexible deformable body to the through hole and whose front end is fixed and pushed to the inner wall of the through hole. The cross-sectional shape of the through hole may be deformed to define the irradiation field (corresponding to the invention of claim 5).

  The plurality of arms may be arranged radially around the through hole (corresponding to the invention of claim 6).

  The tip of the arm may be flush with the inner wall of the through hole (corresponding to the invention of claim 7).

  The plurality of arms are opposed to each other with the flexible deformable body interposed therebetween, and one of the opposed arms is fixed to the upper end of the through hole, and the other of the opposed arms is fixed to the lower end of the through hole. You may make it (it corresponds to the invention of Claim 8).

  The arm may be pushed and pulled so as to deform the through hole into a tapered shape (corresponding to the invention of claim 9).

  The cylindrical shape of the through hole is tapered by increasing the amount that the other arm is pulled to the side of the flexible deformation body than the amount that one of the facing arms is pulled to the side surface of the flexible deformation body. You may make it deform | transform into (it is equivalent to the invention of Claim 10).

  You may make it further provide the pusher which presses the side surface of the said flexible deformation body, and shape | molds the said through-hole in the cross-sectional shape which consists of polygons (equivalent to invention of Claim 11).

  The invention described in claim 12 for solving the above-mentioned problem is a radiation therapy apparatus for generating radiation and exposing the generated radiation by defining an irradiation field thereof, wherein the radiation source generates the radiation. And a donut-shaped flexible deformable body that is filled with a powder that absorbs radiation and has a through hole formed along the radiation exposure axis, and a shape control unit that deforms the cross-sectional shape of the through hole It is characterized by providing.

  In the present invention, a powder that absorbs radiation is filled, and a donut-shaped flexible deformable body having a through hole formed along the radiation exposure axis is provided, and the cross-sectional shape of the through hole is deformed. It was decided to define the irradiation field.

  According to this, the irradiation field can be freely deformed over the entire circumference. In addition, a drive mechanism for deforming the cross-sectional shape of the through hole can be arranged around the entire periphery, and the arrangement structure of the drive mechanism can be simplified and the cost can be reduced.

  FIG. 1 is a schematic diagram illustrating a configuration example of a radiation therapy apparatus 1 according to the present embodiment. The radiation therapy apparatus 1 is an apparatus for treating an affected area of a subject. The affected part is treated by generating radiation and exposing it to the affected part of the subject.

  The radiotherapy apparatus 1 includes a treatment table 2 on which a subject is placed, a rotating frame 3 that exposes radiation, and a rotation support table 4 that rotatably supports the frame 3.

  The treatment table 2 is provided with a top plate 21 that can be moved in the body axis direction of the subject (in the direction of arrow A in FIG. 1), and can move up and down (in the direction of arrow B in FIG. 1). is there. The treatment table 2 can be rotated (arrow C in FIG. 1) in which the surface of the top plate 21 maintains a parallel relationship with the installation surface of the radiotherapy device 1.

  The rotation support 4 is fixed to the apparatus installation surface, and supports the rotation mount 3 via a rotation shaft 41. The rotation support table 4 rotates the rotation shaft 41 so that the rotation frame 3 can rotate in the direction around the axis (arrow D in FIG. 1).

  The rotary mount 3 has a three-dimensional shape with a substantially L-shaped cross section. Of the substantially L-shaped solid shape, one arm 3a is supported by the rotation support base 4, and the other one arm 3b is provided with the irradiation head 5. The irradiation head 5 is disposed to face the treatment table 2.

  The irradiation head 5 is provided with a radiation source S and exposes the radiation to the subject. The radiation source S is composed of an electron accelerator, a counter-electron beam target, and the like, and generates radiation by accelerating electrons with the electron accelerator and colliding with the counter-electron beam target. The generated radiation is a photon beam (X-ray, γ-ray, etc.), electron beam, heavy particle beam (proton, helium, carbon, neon, π-meson beam, neutron beam, etc.).

  In this radiotherapy apparatus 1, the subject is placed on the top plate 21, and the affected part irradiated with radiation is the axis of the rotating shaft 41 (one-dot chain line in the figure) and the axis of the irradiation head 5 (also one-dot chain line in the figure). ) Is moved in the body axis direction, vertically moved and rotated, and rotated around the axis of the rotating gantry 3 so as to be located at the isocenter that intersects.

  When the affected area is located at the isocenter, the irradiation field F or the like is adjusted to irradiate the affected area with radiation from the radiation source. The irradiation field F is a region where radiation is irradiated, and is defined according to the shape of the affected area. The irradiation head 5 is provided with an original diaphragm device 6, and an irradiation field F is defined by the original diaphragm device 6.

  2 and 3 are views showing the original material drawing device 6. FIG. FIG. 2 is a perspective view of the original diaphragm device 6. FIG. 3 is a side view of the original material drawing device 6.

  As shown in FIGS. 2 and 3, the original aperture device 6 has a flexible block 61 arranged on the radiation exposure axis with the radiation source S side as the upper surface and the treatment table 2 side as the lower surface. The flexible block 61 has a predetermined thickness in the exposure axis direction and has a flexibility that can be deformed by an external force.

  The flexible block 61 is filled with powder that absorbs radiation, such as tungsten and molybdenum. A through hole 62 is provided in the center of the flexible block 61 along the radiation exposure axis of the radiation source S, and the flexible block 61 has a donut shape. The through hole 62 transmits radiation, and its cross-sectional shape defines an irradiation field F.

  In the present embodiment, the flexible block 61 is a flexible bag, and a powder that absorbs radiation is sealed in the internal space. The inner wall of the through hole 62 is also a part of the bag body and has the same composition as the bag body. The flexible block 61 is made of rubber, for example. The envelope of the bag is also filled with powder that absorbs radiation.

  It is desirable that the volume composition ratio of the powder with respect to the volume of the flexible block 61 is equal to or greater than the ratio that can absorb the radiation exposed from the radiation source S by the thickness of the flexible block 61 and that the flexible block 61 can be deformed by an external force.

  In the flexible block 61, a plurality of arms 63 are arranged transversely from the side surface of the flexible block 61 toward the through hole 62. The plurality of arms 63 are arranged radially around the through hole 62. In addition, the plurality of arms 63 are disposed opposite to each other on the upper surface and the lower surface with the flexible block 61 interposed therebetween.

  For example, the plurality of arms 63 are arranged radially from four directions with an angle between adjacent arms 63 being 90 degrees, and are arranged radially from 16 directions with an angle between adjacent arms 63 being 22.5 degrees. To do.

  The tip of the arm 63 is positioned flush with the inner wall of the through hole 62 and is fixed to the inner wall of the through hole 62. The arm 63 traversing the upper surface of the flexible block 61 is fixed to the inner wall at the upper end of the through hole 62, and the arm 63 traversing the lower surface is fixed to the inner wall at the lower end of the through hole 62.

  The other end of this arm 63 is connected to a drive mechanism such as a motor and gear (not shown), and is pushed and pulled independently in the direction in which the arm 63 extends. The cross-sectional shape of the through hole 62 is controlled so as to match.

  A pusher 64 that presses the side surface of the flexible block 61 is disposed on the side surface of the flexible block 61. For example, the pusher 64 is disposed on each of the four side surfaces of the flexible block 61. The pusher 64 abuts against the side surface of the flexible block 61, and a spring body 64a is connected to the back surface. The pusher 64 presses the side surface of the flexible block 61 by the biasing force of the spring body 64a on the back surface.

  4 and FIG. 5 show how the irradiation field F is defined by the original diaphragm device 6. FIG. 4 is a top view of the original diaphragm device 6 that defines the irradiation field F. FIG. FIG. 5 is a side view of the original diaphragm device 6 that defines the irradiation field F. FIG.

  As shown in FIGS. 4 and 5, the original material drawing device 6 pulls the arm 63 in an independent amount of movement in the lateral direction of the flexible block 61. Since the tip of the arm 63 is fixed to the inner wall of the through hole 62, the inner wall of the through hole 62 is pulled in the lateral direction of the flexible block 61 as the arm 63 moves backward, and the through hole 62 expands.

  By adjusting the amount by which the arm 63 is pulled, the through hole 62 is deformed into a shape in which the edge passes through the tip of each arm 63. By controlling the retraction amount of the arm 63 so that the through hole 62 matches the affected part shape, the through hole 62 matches the affected part shape.

  When pulling the arm 63, the amount Lb of pulling the arm 63 traversed on the lower surface of the flexible block 61 facing the arm 63 is set larger than the amount La of pulling the arm 63 traversed on the upper surface of the flexible block 61. The lower end of the through hole 62 is pulled toward the side surface of the flexible block 61 rather than the upper end, and the inner wall of the through hole 62 is inclined in a tapered shape. The inclination angle of the inner wall is adjusted so that the radiation source S is captured on the extended line of the inclined inner wall. By adjusting the inclination of the inner wall of the through hole 62, the influence of the penumbra of the irradiation field F is suppressed.

  The pusher 64 presses the side surface of the flexible block 61 by the urging force of the spring body 64a on the back surface, and complements the formation of the cross-sectional shape of the through hole 62. Pressure is applied to the outer edge line of the through hole 62 that draws a curve due to the elasticity of the flexible block 61, and the outer edge line is formed into a linear shape so that the cross-sectional shape of the through hole 62 is a polygon.

  In the radiotherapy apparatus 1 including the active substance restricting device 6 according to the present embodiment, when the active substance restricting device 6 exposes the radiation from the radiation source S in a state where the through hole 62 is pulled and deformed by the arm 63, it is deformed by tension. With the cross-sectional shape of the through hole 62 as an irradiation field F, the radiation is exposed to the affected area.

  The original diaphragm device 6 can freely deform the irradiation field F over the entire circumference by adjusting the pulling amount of each arm 63 to freely deform the through hole 62. Further, the outer edge line between the tips of the adjacent arms 63 is formed into a straight line by the pusher 64 to define the irradiation field F with high accuracy. Furthermore, the inclination angle of the inner wall of the through hole 62 can be freely adjusted, and the influence of the penumbra blur of the irradiation field F can be suppressed.

  Also, in the original aperture device 6 of the present embodiment, by arranging the arms 63 radially, the drive mechanism of the arms 63 can be disposed on the entire circumference of the flexible block 61, so that it is possible to easily cope with an increase in the drive mechanisms.

  The flexible block 61 may be a lump filled with a flexible material that can be elastically deformed in addition to the bag body. For example, a rubber lump is mixed with a powder that absorbs radiation.

  In addition, the arm 63 may be inserted into the through hole 62 from the side surface of the flexible block 61. According to the stab arrangement, the number of arms 63 traversing from one direction can be reduced to one each, and a margin can be given to the arrangement layout of the drive mechanism. The inner wall of the through hole 62 can be inclined when the arm 63 is pulled by fixing the tip of the arm 63 so as to be shifted from the midpoint of the cylinder length of the through hole 62 in the opening direction on the treatment table 2 side.

It is an external view which shows the structure of the radiotherapy apparatus which concerns on this embodiment. It is a perspective view of an original diaphragm device concerning this embodiment. It is a side view of the original aperture device concerning this embodiment. It is a top view which shows the irradiation field definition state of the original-body aperture device which concerns on this embodiment. It is a side view which shows the irradiation field definition state of the original-body aperture device which concerns on this embodiment. It is a side view of the conventional original body aperture apparatus. It is a perspective view of the conventional original body aperture apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radiation therapy apparatus 2 Treatment table 21 Top plate 3 Rotating mount 3a One arm 3b One arm 4 Rotating support base 41 Rotating shaft 5 Irradiation head 6 Original diaphragm | throttle device 61 Flexible block 62 Through-hole 63 Arm 64 Pusher 64a Spring body

Claims (22)

An active diaphragm device that defines a radiation field,
A donut-shaped flexible deformation body filled with a powder that absorbs radiation and having a through-hole formed along the radiation exposure axis;
A shape control unit for deforming the cross-sectional shape of the through hole;
Providing
The original diaphragm device characterized by this. The flexible deformable body is a bag body, sealed with a powder that absorbs radiation;
The original material drawing apparatus of Claim 1 characterized by these. The outer shell of the bag body is filled with powder that absorbs radiation,
The original material drawing apparatus of Claim 2 characterized by these. The flexible deformation body is made of rubber;
The original material drawing apparatus of Claim 1 characterized by these. The shape control unit includes a plurality of arms that are transversely arranged from the side surface of the flexible deformable body to the through hole, and whose tip is fixed and pushed to the inner wall of the through hole,
Defining the irradiation field by deforming the cross-sectional shape of the through hole by pushing and pulling the arm;
The original material drawing apparatus of Claim 1 characterized by these. The plurality of arms are arranged radially around the through hole;
The original material drawing apparatus of Claim 5 characterized by these. The tip of the arm is flush with the inner wall of the through hole;
The original material drawing apparatus of Claim 5 characterized by these. The plurality of arms are opposed to each other with the flexible deformable body interposed therebetween, and one of the opposed arms is fixed to the upper end of the through hole, and the other of the opposed arms is fixed to the lower end of the through hole. That
The original material drawing apparatus of Claim 5 characterized by these. The arm is pushed and pulled to deform the through hole into a tapered shape;
The original material drawing apparatus of Claim 5 characterized by these. The cylindrical shape of the through hole is tapered by increasing the amount that the other of the opposing arms is pulled toward the side of the flexible deformable body than the amount that the one of the facing arms is pulled toward the side of the flexible deformable body. Transforming into a shape,
9. The device for reducing the size of the active material according to claim 8. Further comprising a pusher for pressing the side surface of the flexible deformable body to form the through hole into a polygonal cross-sectional shape;
The original material drawing apparatus of Claim 5 characterized by these. A radiotherapy device that generates radiation and exposes the generated radiation by defining an irradiation field thereof,
A radiation source that generates radiation; and
A donut-shaped flexible deformation body filled with a powder that absorbs radiation and having a through-hole formed along the radiation exposure axis;
A shape control unit for deforming the cross-sectional shape of the through hole;
Providing
A radiotherapy apparatus characterized by the above. The flexible deformable body is a bag body, sealed with a powder that absorbs radiation;
The radiotherapy apparatus according to claim 12. The outer shell of the bag body is filled with powder that absorbs radiation,
The radiotherapy apparatus according to claim 13. The flexible deformation body is made of rubber;
The radiotherapy apparatus according to claim 12. The shape control unit includes a plurality of arms that are arranged transversely from the side surface of the flexible deformation body to the through hole, and whose tip is fixed and pushed to the inner wall of the through hole,
Defining the irradiation field by deforming the cross-sectional shape of the through hole by pushing and pulling the arm;
The radiotherapy apparatus according to claim 12. The plurality of arms are arranged radially around the through hole;
The radiotherapy apparatus according to claim 16. The tip of the arm is flush with the inner wall of the through hole;
The radiotherapy apparatus according to claim 16. The plurality of arms are arranged opposite to each other with the flexible deformable body interposed therebetween, and one of the opposed arms is fixed to the upper end of the through hole, and the other of the opposed arms is fixed to the lower end of the through hole. That
The radiotherapy apparatus according to claim 16. The arm is pushed and pulled so as to deform the through hole into a tapered shape;
The radiotherapy apparatus according to claim 16. The cylindrical shape of the through hole is tapered by increasing the amount that the other arm is pulled to the side of the flexible deformable body than the amount that one of the facing arms is pulled to the side of the flexible deformable body. Transforming into,
The radiotherapy apparatus according to claim 19. Further comprising a pusher for pressing the side surface of the flexible deformable body to form the through hole into a polygonal cross-sectional shape;
The radiotherapy apparatus according to claim 16.

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