JP2008206563A - Multileaf collimator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the high-speed actuation of leaves while improving the shape accuracy of the irradiation field of beams. <P>SOLUTION: This multileaf collimator 200 is provided with a plurality of leaves, a plurality of feed screws threadedly engaged with screw holes 8a of the plurality of leaves and, for example, a plurality of rotary machines 6 for rotating the plurality of feed screws 5 respectively; and forms the irradiation field 3 of radiation beams according to the disposition of the plurality of leaves 4, wherein the leaf 4 has a leaf body 7, a female screw part 8 formed integrally with the leaf body 7, configured to increase the thickness more than the leaf body 7 and having a screw hole 8a, and a through-hole 7a formed in the leaf body 7 corresponding to the moving area of the feed screw 5 threadedly engaged with the screw hole 8a of the female screw part 8; the female screw part 8 of mutually adjoining leaves 4 and the through-hole 7a are formed in different positions in the height direction; and a groove 7b is formed in the leaf body 7 corresponding to the relative movement area of the female screw 8 of the mutually adjoining leaves 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multi-leaf collimator that forms an irradiation field of a radiation beam in accordance with the shape of a target. More specifically, the present invention relates to a multi-leaf collimator including a driving unit that drives a leaf via a feed screw.

  As a typical example of irradiating a target in an irradiation target with a radiation beam (for example, X-ray, proton beam, electron beam, etc.), radiation is applied to cancer cells (hereinafter referred to as an affected area) in the patient's body. The case where it irradiates is mentioned. In this case, the irradiation target corresponds to the patient, and the target corresponds to the affected area. When irradiating the affected part in the patient body with radiation, if the radiation field (irradiation range) of the radiation beam and the shape of the affected part do not coincide, the normal part around the affected part is also irradiated with radiation. When radiation is irradiated to a normal site around the affected area, the normal site may be adversely affected. Therefore, it is preferable to precisely limit the radiation beam irradiation field in light of the affected site.

  A multi-leaf collimator is known as one of means for forming an irradiation field of such a radiation beam. The multi-leaf collimator includes, for example, a plurality of leaves, a plurality of feed screws (screw screws) respectively screwed into screw holes of the plurality of leaves, and a plurality of stepping motors that respectively rotate the plurality of feed screws. Is disclosed (for example, see Patent Document 1).

JP-A-7-255718 (FIG. 3)

However, there are the following problems in the above-described prior art.
The multi-leaf collimator can make the beam irradiation field as close as possible to the shape of the affected area by reducing the thickness of the leaf and increasing the number of leaves and increasing the number of divisions of the beam irradiation field by these leaves. However, in the multi-leaf collimator that drives the leaf by screwing the feed screw into the screw hole of the leaf, it is usually necessary to reduce the diameter of the feed screw in order to reduce the thickness of the leaf. When this thin feed screw is rotated at a high speed, there is a risk that the feed screw may be greatly shaken to come into contact with surrounding components. For this reason, it is necessary to suppress the rotational speed of the feed screw, and the decrease in the drive speed of the leaf cannot be avoided.

  An object of the present invention is to provide a multi-leaf collimator capable of achieving high-speed driving of a leaf while improving the shape accuracy of a beam irradiation field.

  (1) In order to achieve the above object, the present invention includes a plurality of leaves, a plurality of feed screws respectively screwed into screw holes of the plurality of leaves, and a driving means for rotating the plurality of feed screws. A multi-leaf collimator for forming an irradiation field of a radiation beam according to the arrangement of the plurality of leaves, wherein the leaf is integrated with the leaf main body and the leaf main body and is thicker than the leaf main body. And a through hole formed in the leaf main body corresponding to a moving region of the feed screw that is screwed into the screw hole of the female screw portion and adjacent to each other. The positions of the female screw portion and the through hole of the leaf to be changed are different in the height direction, and a groove is formed in the leaf body corresponding to the relative movement region of the female screw portions adjacent to each other.

  In the present invention, since the thickness of the female screw portion is made larger than that of the leaf main body portion, the diameter dimension of the feed screw that is screwed into the screw hole of the female screw portion can be increased. Thereby, the rotational speed of the feed screw can be increased, and the leaf can be driven at a high speed. On the other hand, the thickness of the leaf body can be made thinner than the female thread portion. Further, by changing the positions of the female screw portions and the through holes of the adjacent leaves in the height direction, and forming grooves in the leaf body corresponding to the relative movement regions of the adjacent female screw portions of the leaves, a plurality of Leaves can be arranged without gaps in the thickness direction. Therefore, the number of leaves can be reduced by increasing the number of leaves, the number of divisions of the beam irradiation field by these leaves can be increased, and the shape accuracy of the beam irradiation field can be increased.

  (2) In order to achieve the above object, the present invention also provides a plurality of leaves, a plurality of feed screws respectively screwed into screw holes of the plurality of leaves, and a driving means for rotating the plurality of feed screws. A multi-leaf collimator that forms an irradiation field of a radiation beam according to the arrangement of the plurality of leaves, wherein the leaves are formed to have a leaf body portion and a thickness greater than that of the leaf body portion. A female screw portion attached to the main body portion and having the screw hole; and a through hole formed in the leaf main body portion corresponding to a moving region of the feed screw screwed into the screw hole of the female screw portion, The positions of the female screw portion and the through hole of the adjacent leaf are made different in the height direction, and a groove is formed in the leaf body corresponding to the relative movement region of the female screw portion of the adjacent leaf. To.

  (3) In the above (1) or (2), preferably, the driving means is a plurality of rotating machines that are coaxially connected to the plurality of feed screws.

  According to the present invention, it is possible to drive the leaf at high speed while improving the shape accuracy of the beam irradiation field.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a conceptual configuration diagram showing an overall system configuration of a radiation beam irradiation apparatus including a multi-leaf collimator according to the present embodiment.

  This radiation beam irradiation apparatus outputs a radiation beam such as a charged particle beam accelerated by the synchrotron 101 (hereinafter, appropriately referred to as a beam) from the rotary irradiation apparatus 102 based on the control of the control device 23, and transmits the beam to the affected area of the patient K. The rotation irradiation device 102 can irradiate the affected part with a beam from a plurality of directions by rotating around the rotation axis. In addition to the synchrotron 101, a cyclotron, a linear accelerator, a laser accelerator, or the like may be used as a charged particle acceleration means.

(1) Configuration and operation of the synchrotron 101 The synchrotron 101 includes a high-frequency applying device 111 that increases the betatron oscillation amplitude of the beam by applying a high-frequency magnetic field and electric field (hereinafter referred to as a high-frequency electromagnetic field) to the beam, A bending electromagnet 112 that bends the trajectory of the beam, a quadrupole electromagnet 113 that controls betatron oscillation of the beam, a hexapole electromagnet 114 that excites resonance during beam emission, and a high frequency that gives energy to the beam, that is, accelerates the beam. An acceleration cavity 115, an injector 116 that makes a beam incident on the synchrotron 101, and an output deflector 117 that emits the beam from the synchrotron 101 are provided.

  When the control device 23 outputs an emission command to the pre-stage accelerator 104, the pre-stage accelerator 104 emits a low energy beam in accordance with this, and the beam is guided to the injector 116 of the synchrotron 101 via the beam transport system. Is incident on the synchrotron 101. The incident beam circulates in the synchrotron 101 as the trajectory is bent by the deflecting electromagnet 112. At this time, the beam circulates stably in the synchrotron 101 by appropriately controlling the frequency of the betatron vibration by the excitation amount of the quadrupole electromagnet 113. Then, in the circulation process, a high frequency electric field is applied to the beam from the high frequency acceleration cavity 115, whereby energy is given to the beam, the beam is accelerated, and energy is increased. When the energy of the beam circulating in the synchrotron 101 increases to the energy E, the application of energy to the beam by the high-frequency acceleration cavity 115 is stopped, and the quadrupole electromagnet 113, the hexapole electromagnet 114, and the high-frequency application device 111 are known. By changing the orbital gradient of the beam by the control, the betatron oscillation amplitude is rapidly increased by resonance, and the beam is emitted from the synchrotron 101 by the emission deflector 117.

  In the operation of the synchrotron 101 described above, the control device 23 performs a predetermined irradiation direction (usually irradiation from a plurality of directions) based on the depth position of the affected part input from the treatment planning device (details will be described later) 24. To determine the energy E of the beam irradiated to the affected area. Further, the synchrotron 101 emits the beam of energy E and the beam of energy E required for accelerating the beam to energy E and supplied to each of the deflection electromagnet 112, the quadrupole electromagnet 113, and the high-frequency acceleration cavity 115. A current value to be supplied to the high-frequency applying device 111 and the hexapole electromagnet 114 is calculated. The calculated current values are stored in the storage means in the control device 23 in correspondence with the energy E for each device, and are output to the power supply 108 or the power supply 109 during acceleration or extraction.

(2) Configuration and Operation of Rotating Irradiation Device 102 The beam emitted from the synchrotron 101 is input to the rotating irradiation device 102. The rotary irradiation device 102 includes a gantry 122 to which a deflection electromagnet 123, a quadrupole electromagnet 124, and an emission nozzle 120 are attached, and a motor 121 that rotationally drives the gantry 122 about a predetermined rotation axis (see FIG. 1). .

  The beam input to the rotary irradiation device 102 is first bent in its trajectory by the deflecting electromagnet 123, and betatron vibration is adjusted by the quadrupole electromagnet 124 and guided to the emission nozzle 120. The beam guided to the emission nozzle 120 first passes between the magnetic poles of the scanning electromagnets 201 and 202. The scanning electromagnets 201 and 202 are supplied with a sine wave alternating current having a phase difference of 90 degrees from the power supplies 201A and 202A, and the scanning electromagnets 201 and 202 generate beams passing between the magnetic poles of the scanning electromagnets 201 and 202. The magnetic field is deflected so as to be scanned in a circular shape at the affected area.

  The beams that have passed through the scanning electromagnets 201 and 202 are scattered by the scatterer 203 and the diameter of the beam is expanded, and then pass through the ridge filter 204A (or 204B). The ridge filter 204A (or 204B) attenuates the energy of the beam at a predetermined rate, and gives the beam energy a distribution corresponding to the thickness of the affected part. After the dose is measured by the dose monitor 205, the beam is input to the bolus 206A (or 206B) to obtain an energy distribution corresponding to the lower shape of the affected area, and further shaped into the horizontal shape of the affected area by the multi-leaf collimator 200. Then, the affected area is irradiated.

  Here, as described above, normally, the beam is irradiated to the tube portion from a plurality of directions. The present embodiment shows an example of irradiation from two irradiation directions as an example, and the two ridge filters 204A and 204B each have two irradiation directions according to the thickness of the affected part determined by the treatment planning device 24. The boluses 206A and 206B are also prepared in advance for each of the two irradiation directions in accordance with the obtained lower shape of the affected part. The manufactured ridge filters 204A and 204B are installed on the rotary table 204C, and the boluses 206A and 206B are installed on the rotary table 206C. At this time, the rotation axis of the rotary table 206C and the center of the beam trajectory are eccentric, and by rotating the rotary table 206C, the bolus 206A or the bolus 206B is alternately placed on the beam trajectory, thereby two irradiations. A beam energy distribution corresponding to both directions can be formed. The rotary table 204C has the same configuration as the rotary table 206C.

  When the irradiation direction is set or changed, an inclination angle signal corresponding to the irradiation direction is output from the control device 23 to the motor 121, and the motor 121 rotates the gantry 122 to the inclination angle. Is moved from the irradiation direction to a position where the affected part can be irradiated with the beam. Further, the control device 23 instructs each of the rotary tables 204C and 206C to arrange the ridge filter 204A (or 204B) and the bolus 206A (or 206B) corresponding to the irradiation direction on the beam trajectory. , And the rotary tables 204C and 206C rotate according to this.

  At this time, the control device 23 outputs a control signal corresponding to the irradiation direction to the collimator controller (leaf position control computer) 22, and the collimator controller 22 responds accordingly to the multi-leaf collimator as shown in FIG. Drive control is performed so that a plurality of leaves (thin plate-like blocks) 4 provided in 200 are abutted and a beam irradiation field (irradiation range) 3 matching the horizontal shape of the affected part viewed from the irradiation direction is realized by the gap. To do. As a result, among the beams that have passed through the bolus 206A (or 206B) and reached the multi-leaf collimator 200 (the beam irradiation region from the beam source 2 shown in FIG. 2), the components that are directed to other than the irradiation field 3 are a plurality of leaves 4. Therefore, irradiation to unnecessary parts can be avoided.

(3) Configuration and Operation of Multi-leaf Collimator 200 FIG. 2 is a perspective view showing the overall structure of the multi-leaf collimator 200. FIG. 3 is a perspective view showing the detailed structure of the leaf of this embodiment, and FIG. 4 is a partial cross-sectional view showing the detailed structure of the multi-leaf collimator of this embodiment.

  2 to 4, the multi-leaf collimator 200 includes a plurality of leaves 4, a plurality of feed screws 5 respectively screwed into screw holes 8 a of the plurality of leaves 4, and a plurality of feed screws 5. And a plurality of motors 6 (drive means) connected coaxially. The leaves 4 are slidably arranged in a direction of approaching or separating from each other as a set of two sheets, and the plurality of sets are arranged in a direction perpendicular to the beam irradiation direction. Then, the feed screw is rotated by driving each motor 6, and the leaf screwed to the feed screw is moved and arranged to form a beam irradiation field 3 that matches the shape of the affected part.

  The leaf 4 of the present embodiment includes a leaf body portion 7 and a rectangular parallelepiped internal thread portion 8 that is integrally formed with the leaf body portion 7 and has a thickness greater than that of the leaf body portion 7 and has a screw hole 8a. is doing. A through hole 7 a is formed in the leaf main body portion 7 so as to correspond to the moving region of the feed screw 5 screwed into the screw hole 8 a of the female screw portion 8 so that the feed screw 5 does not interfere with the leaf main body portion 7. It has become. Then, the positions of the female screw portion 8 and the through hole 7a of the leaf 4 adjacent to each other are made different in the height direction (in this embodiment, they are alternately arranged at two height positions as shown in FIG. 4), and Grooves 7 b are formed on both side surfaces of the leaf main body portion 7 in correspondence with the relative movement region of the female screw portion 8 of the adjacent leaf 4. The depth of the groove 7b of the leaf body 7 is equal to or greater than the protruding length of the female thread 8 in the thickness direction.

  In the present embodiment configured as described above, the thickness of the female screw portion 8 is made larger than that of the leaf main body portion 7, so that the diameter dimension of the feed screw 5 screwed into the screw hole 8a of the female screw portion 8 can be increased. it can. Thereby, the rotational speed of the feed screw 5 can be increased, and the leaf 4 can be driven at a high speed. On the other hand, the thickness of the leaf body 7 can be made thinner than the female thread 8. Further, the positions of the female screw portion 8 and the through hole 7a of the leaf 4 adjacent to each other are made different in the height direction, and the groove 7b is formed in the leaf body portion 7 corresponding to the relative movement region of the female screw portion 8 of the leaf 4 adjacent to each other. By forming, the plurality of leaves 4 can be arranged without gaps in the thickness direction. Therefore, the thickness of the leaf 4 can be reduced to increase the number of sheets, the number of divisions of the beam irradiation field by the leaves 4 can be increased, and the shape accuracy of the beam irradiation field can be increased.

  Further, in the present embodiment, by forming a through hole 7 a in the leaf body portion 7 corresponding to the moving region of the feed screw 5, the female screw portion 8 and the feed screw 5 are overlapped in the length direction of the leaf body portion 7. Can be arranged. Thus, for example, unlike a configuration in which a metal fitting or the like is attached so as to extend from the leaf main body, and the feed screw is screwed into the screw hole of the metal fitting to drive the leaf, the feed screw 5 or the motor 6 is attached to the leaf 4. It can arrange | position so that it may not protrude largely in a length direction, a downward direction, and right and left. Further, the position of the motor 6 coaxially connected to the adjacent feed screw 5 can be varied in the height direction, and the motor 6 can be arranged so as not to interfere. Therefore, it is possible to reduce the size of the entire apparatus.

  Further, since the groove 7b is formed in the leaf main body portion 7 corresponding to the relative movement region of the female screw portion 8 of the adjacent leaf 4 as compared with the case where a through hole is formed instead of the groove 7b, for example. The structural strength of the leaf 4 can be increased.

  Next, another embodiment of the present invention will be described with reference to FIGS. This embodiment is an embodiment in which a leaf main body portion and a female screw portion are separately formed and attached.

  FIG. 5 is a perspective view showing a detailed structure of a leaf constituting the multi-leaf collimator of the present embodiment, and FIG. 6 is an exploded perspective view. FIG. 7 is a partial cross-sectional view showing the detailed structure of the multi-leaf collimator of this embodiment. In addition, the same code | symbol is attached | subjected to the part equivalent to the said one Embodiment, and description is abbreviate | omitted suitably.

  In the leaf 10 of this embodiment, the leaf main body portion 11 and the female screw portion 12 are formed as separate bodies, and the female screw portion 12 is attached to the end side of the notch 11 a of the leaf main body portion 11. A flange 12a extending in the vertical direction is formed on both sides in the thickness direction (left side and right side in the figure) of the rectangular parallelepiped female screw portion 12, and a through hole 12b is formed in the flange 12a. A through hole 11 b corresponding to the through hole 12 b of the female screw part 12 is formed in the leaf main body part 11. Then, by inserting the round bar 13 through the through hole 12 b of the female screw part 12 and the through hole 11 b of the leaf main body part 11, the female screw part 12 is fixed to the leaf main body part 11. At this time, the through hole 14 (a part of the notch 11a of the leaf main body 11) formed by the leaf main body 11 and the female screw 12 moves the feed screw 5 screwed into the screw hole 12c of the female screw 12. This corresponds to the region, and the feed screw 5 does not interfere with the leaf body 11.

  Also in the present embodiment configured as described above, the diameter of the feed screw 5 that is screwed into the screw hole 12c of the female screw portion 12 is increased because the thickness of the female screw portion 12 is larger than that of the flange main body portion 11 as in the above-described one embodiment. The dimensions can be increased. Thereby, the rotational speed of the feed screw 5 can be increased and the leaf 10 can be driven at high speed. On the other hand, the thickness of the leaf body 11 can be made thinner than the female thread 12. Further, the positions of the female screw portion 12 and the through hole 14 of the leaf 10 adjacent to each other are made different in the height direction (in this embodiment, they are alternately arranged at two positions as shown in FIG. 7) and are adjacent to each other. By forming the grooves 11c on both side surfaces of the leaf body 11 corresponding to the relative movement region of the female screw portion 12 of the leaf 10, the plurality of leaves 10 can be arranged without gaps in the thickness direction. Therefore, the thickness of the leaf 10 can be reduced to increase the number of the sheets, the number of divisions of the beam irradiation field by the leaf 10 can be increased, and the shape accuracy of the beam irradiation field can be increased.

  Further, as in the above-described embodiment, the entire apparatus can be reduced in size. Further, for example, the structural strength of the leaf 10 can be increased as compared with a case where a through hole is formed instead of the groove 11c.

  Further, in the present embodiment, the leaf body 11 and the female thread 12 are formed as separate bodies, so that cutting work is performed as compared with the case where the leaf body 11 and the female thread 12 are integrally formed as in the above embodiment. The cost can be reduced and the cost can be reduced.

  In the embodiment described above, the structure in which the female screw portions and the through holes of the adjacent leaves are alternately arranged at two positions so that the positions of the through holes are different in the height direction has been described as an example. However, the present invention is not limited thereto. . That is, for example, a structure in which three or more positions are sequentially arranged may be employed. In such a case, the same effect as described above can be obtained.

It is a notional block diagram showing the whole system configuration of a radiation beam irradiation apparatus provided with one embodiment of the multi-leaf collimator of the present invention. It is a perspective view showing the whole structure of one Embodiment of the multi-leaf collimator of this invention. It is a perspective view showing the detailed structure of the leaf which comprises one Embodiment of the multi-leaf collimator of this invention. It is a fragmentary sectional view showing the detailed structure of one Embodiment of the multi-leaf collimator of this invention. It is a perspective view showing the detailed structure of the leaf which comprises other embodiment of the multi-leaf collimator of this invention. It is a disassembled perspective view showing the detailed structure of the leaf which comprises other embodiment of the multi-leaf collimator of this invention. It is a fragmentary sectional view showing the detailed structure of other embodiments of the multi-leaf collimator of the present invention.

Explanation of symbols

3 Irradiation field 4 Leaf 5 Feed screw 6 Motor (drive means)
7 Leaf body portion 7a Through hole 7b Groove 8 Female thread portion 8a Screw hole 10 Leaf 11 Leaf main body portion 11c Groove 12 Female thread portion 12c Screw hole 14 Through hole 200 Multi-leaf collimator

Claims (3)

A plurality of leaves; a plurality of feed screws respectively screwed into screw holes of the plurality of leaves; and a driving means for rotating the plurality of feed screws, and a radiation beam corresponding to the arrangement of the plurality of leaves. In the multi-leaf collimator that forms the irradiation field,
The leaf is formed integrally with the leaf main body portion and the leaf main body portion so as to be thicker than the leaf main body portion, the female screw portion having the screw hole, and the screw screwed into the screw hole of the female screw portion. Having a through hole formed in the leaf body corresponding to the moving region of the feed screw,
The positions of the female screw portion and the through hole of the leaf adjacent to each other are made different in the height direction, and a groove is formed in the leaf body corresponding to the relative movement region of the female screw portion of the leaf adjacent to each other. Multi-leaf collimator. A plurality of leaves; a plurality of feed screws respectively screwed into screw holes of the plurality of leaves; and a driving means for rotating the plurality of feed screws, and a radiation beam corresponding to the arrangement of the plurality of leaves. In the multi-leaf collimator that forms the irradiation field,
The leaf is formed so as to be thicker than the leaf main body, and is attached to the leaf main body, the female screw having the screw hole, and the screw screwed into the screw hole of the female screw Having a through hole formed in the leaf body corresponding to the moving region of the feed screw,
The positions of the female screw portion and the through hole of the leaf adjacent to each other are made different in the height direction, and a groove is formed in the leaf body corresponding to the relative movement region of the female screw portion of the leaf adjacent to each other. Multi-leaf collimator.   3. The multi-leaf collimator according to claim 1, wherein the driving means is a plurality of rotating machines that are coaxially connected to the plurality of feed screws.

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