JP4774495B2 - Charged particle beam irradiation equipment - Google Patents

Description

  The present invention relates to a charged particle beam irradiation apparatus that irradiates an irradiation target with a charged particle beam.

Conventionally, as a technique in such a field, a proton beam irradiation apparatus that performs treatment by irradiating a tumor in a patient with a proton beam is known (for example, see Patent Document 1 below). In order to set the shape of the irradiation field of the proton beam, this device expands the generated proton beam in a direction perpendicular to the irradiation direction with a scatterer, and adjusts the energy of the proton beam with a fine degrader. Adjust the depth of the field. Then, the Bragg peak of the proton beam is adjusted through the ridge filter, and the shape of the irradiation field of the proton beam is adjusted through the collimator and the bolus.
Japanese Patent No. 3532739

  In the treatment of such tumors, it is ideal to concentrate a lethal dose only on the tumor tissue so that the surrounding normal tissue is not affected irreversibly. Therefore, higher dose concentration is required. Then, an object of this invention is to provide the charged particle beam irradiation apparatus which can aim at the improvement of dose concentration.

The charged particle beam irradiation apparatus of the present invention is a charged particle beam irradiation apparatus that irradiates an irradiation target with a charged particle beam, a beam expanding unit that expands a beam of the charged particle beam in a direction orthogonal to the irradiation direction, and a charged particle beam expansion and the peak adjustment filter unit for adjusting the Bragg peak, driven with variable shape collimator for adjusting the plane position and shape of the irradiation field of the beam as viewed from the irradiation direction, and a variable shape collimator and the peak adjustment filter section, each While sequentially setting a plurality of irradiation fields that overlap with a part of the irradiation target and viewed from the irradiation direction of the charged particle beam, a charged particle beam is sequentially applied to each of the irradiation fields from the same irradiation direction. and an irradiation control unit that irradiates the irradiation control unit, based on the portion of maximum thickness of the irradiation target object corresponding to the respective irradiation field which is divided into a plurality, the plurality of irradiation field Characterized in that to drive the peak adjustment filter unit to adjust the spread-out Bragg peak width of a charged particle beam in respectively.

  In this charged particle beam irradiation apparatus, the beam of the charged particle beam is expanded in a direction orthogonal to the irradiation direction by the beam expanding unit, and irradiated to the irradiation target through the peak adjustment filter unit and the shape variable collimator. At this time, the shape variable collimator is driven by the control of the irradiation control unit, and the plane position and the plane shape of the irradiation field are set. And an irradiation control part drives a peak adjustment filter part with reference to a target object map, and adjusts the expansion Bragg peak of a charged particle beam. At this time, the peak adjustment filter unit is controlled such that the length of the irradiation field in the irradiation direction corresponds to the length of the irradiation target in the irradiation direction corresponding to the set planar position of the irradiation field. As described above, since a plurality of irradiation fields are sequentially set and irradiation is performed sequentially from the same irradiation direction, an optimal irradiation field matching the shape of the irradiation target can be formed for each irradiation. In this way, it is possible to bring the shape of the entire irradiation field closer to the shape of the irradiation target by repeating optimal irradiation with the shape of the irradiation target and the irradiation field while moving the plane position. As a result, the dose concentration of the charged particle beam can be improved.

In this case, the irradiation control unit drives the shape variable collimator to set the plane position and the plane shape of the irradiation field, and the irradiation direction of the irradiation target with respect to the plane position viewed from the same irradiation direction. Referring to the target map with which the arrangement is associated, adjust the peak so that the length of the irradiation direction of the irradiation field corresponds to the length of the irradiation target irradiation direction corresponding to the set planar position of the irradiation field. The filter unit is driven to adjust the enlarged Bragg peak of the charged particle beam, and in the target map, the target irradiation dose of the beam at the plane position is further associated with the plane position viewed from the same irradiation direction. It is preferable. According to this configuration, it is possible to irradiate each irradiation field with an appropriate dose of charged particle beam while referring to the target map.

  The charged particle beam irradiation apparatus of the present invention preferably further includes a compensation filter that adjusts the shape of the farthest part of the irradiation field. According to this configuration, since the shape of the farthest part of the irradiation field is adjusted by the compensation filter, the shape of the irradiation target and the irradiation field can be adjusted to be closer, and as a result, the charged particle beam The dose concentration can be further improved.

  In addition, the charged particle beam irradiation apparatus of the present invention further includes a beam energy adjusting unit that adjusts the energy of the beam of the charged quantum beam, and the irradiation control unit refers to the target map and is set by the shape variable collimator. It is preferable to control the energy adjusting unit so that the energy of the beam corresponds to the position in the irradiation direction of the irradiation target corresponding to the planar position of the field.

  According to this configuration, the beam energy adjusting unit adjusts the beam energy with reference to the target object map, and adjusts the position of the irradiation field in the irradiation direction to correspond to the position of the irradiation target object. As a result, the dose concentration of the charged particle beam can be further improved.

  According to the present invention, dose concentration can be improved in a charged particle beam irradiation apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a charged particle beam irradiation apparatus according to the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 1 to 3, a proton beam irradiation apparatus (charged particle beam irradiation apparatus) 1 is attached to a rotating gantry 103 in a proton beam therapy apparatus 100 and can be rotated around a treatment table 105 to treat the proton beam therapy apparatus 100. This is a device that irradiates a tumor (irradiation target) P in the body of a patient 51 on a table 105 with a proton beam (charged particle beam) for treatment.

  As shown in FIGS. 2 and 3, the proton beam irradiation apparatus 1 is arranged in order in the proton beam irradiation direction A, and sequentially passes the proton beam and shapes the beam, the scatterer 5, the ridge filter unit 7, and the fine beam. A degrader 9, a block collimator 11, a bolus 13, a multi-leaf collimator 15, and an irradiation control unit 17 that controls driving of each part of the apparatus are provided.

  A proton beam generated by the cyclotron 3 functioning as a proton beam generator is fed into the proton beam irradiation device 1 through a transport device. Then, by passing the thin proton beam that has been fed through, for example, a scatterer (beam expanding portion) 5 made of lead having a thickness of several millimeters, the beam is expanded in a direction perpendicular to the irradiation direction A, and a wide beam is obtained. Expanding.

  The proton beam from the scatterer 5 has a ridge filter portion (peak adjustment) for distributing the proton beam energy depth corresponding to the thickness of the tumor P in the patient 51 (length in the irradiation direction A). The light is incident on the filter unit 7. The ridge filter portion 7 has a plurality of filters 7a in which metal rods whose thickness changes stepwise are arranged in a bowl shape, and the plurality of filters 7a have different protons due to differences in the shape of the metal rods. An extended Bragg peak (hereinafter referred to as “SOBP”) of the line is formed. The ridge filter unit 7 is driven by the control of the irradiation control unit 17 and has a mechanism for inserting a filter appropriately selected from the plurality of filters 7a into a proton beam passing position. With this configuration, the ridge filter unit 7 can selectively change the filter 7a that passes the proton beam, and can adjust the width of the SOBP peak of the proton beam.

  The proton beam that has passed through the ridge filter unit 7 adjusts the beam energy in accordance with the depth of the tumor P in the patient body 51 to be treated, and a fine degrader (beam energy) for adjusting the maximum reachable depth. The light is incident on the adjusting unit 9. The fine degrader 9 is composed of, for example, two wedge-shaped opposing acrylic blocks 9a and 9b. By adjusting the overlapping of the blocks 9a and 9b under the control of the irradiation control unit 17, the proton beam is generated. The thickness of the passing part can be continuously changed. The proton beam loses energy in accordance with the thickness of the substance that has passed through, and the depth that the proton beam reaches within the patient 51 changes. Therefore, by adjusting the fine degrader 9, the position of the Bragg peak of the proton beam is changed within the patient 51. It can be adjusted to the position of the tumor P in the depth direction (irradiation direction A).

  The proton beam that has passed through the fine degrader 9 is incident on a block collimator 11 for roughly shaping the planar shape of the proton beam (the shape viewed from the irradiation direction A). The reason why the block collimator 11 performs shaping in addition to the multi-leaf collimator 15 described later is to prevent secondary radiation from being generated by the block collimator 11 near the patient.

  The proton beam that has passed through the block collimator 11 is input to a bolus (compensation filter) 13 that is, for example, a resin-made irregular filter, and correction is performed regarding the cross-sectional shape of the maximum depth of the tumor P and the tissue non-uniformity. . The shape of the bolus 13 is calculated based on the outline of the tumor and the electron density of the surrounding tissue obtained from, for example, X-ray CT data. By using such a bolus 13, the three-dimensional shape of the farthest part of the proton beam (the portion with the maximum reachable depth) is shaped according to the shape of the maximum depth portion of the tumor P. Concentration can be further enhanced.

  The proton beam passing through the bolus 13 is incident on a multi-leaf collimator (shape variable collimator) 15. The multi-leaf collimator 15 is configured by arranging two shielding portions 15a and 15b made of brass and having a large number of comb teeth with a width of several mm so that the tips of the comb teeth are abutted on the center. Then, under the control of the irradiation control unit 17, the shielding units 15 a and 15 b advance and retract each of the numerous comb teeth in the longitudinal direction, so that the multileaf collimator 15 is positioned at the opening 15 c through which the proton beam passes. And the shape can be changed.

  The proton beam beam that has passed through the multi-leaf collimator 15 is cut into a contour corresponding to the shape of the opening 15c. Therefore, the multi-leaf collimator 15 changes the shape of the opening 15c to change the desired shape of the incident proton beam. A plane position and a plane shape can be cut out. Thus, the proton beam cut out in a desired planar shape at a desired planar position is irradiated to the patient 51 as a therapeutic proton beam. Then, by changing the planar position and planar shape of the opening 15c of the multi-collimator 15 and repeating the irradiation while sequentially moving the irradiation field position in the horizontal direction (direction orthogonal to the irradiation direction A), the entire tumor P is protonated. Irradiate a line beam.

  Further, the proton beam irradiation apparatus 1 includes a dose monitor 23 as means for monitoring the irradiation dose irradiated to the irradiation field. The dose monitor 23 is provided between the fine degrader 9 and the block collimator 11 and detects the dose of the proton beam that passes therethrough. The dose monitor 23 transmits the detected dose as the monitor signal s1 to the irradiation control unit 17, and the irradiation control unit 17 can recognize the irradiation dose irradiated to the irradiation field based on the monitor signal s1.

  Next, processing of the irradiation control unit 17 for performing the irradiation operation as described above will be described with reference to FIGS. 3 and 4. The irradiation control unit 17 refers to the information stored in the tumor map (target object map) 19 created based on the three-dimensional shape of the tumor P of the patient 51, in particular, the ridge filter unit 7, the fine degrader 9, And the operation of the multi-leaf collimator 15 is controlled. Here, the bolus 13 prepared in advance is set at a predetermined position so that the shape of the farthest part of the irradiation field is shaped corresponding to the complicated shape of the maximum depth portion of the tumor. Yes.

  In the tumor map 19, the tumor P is divided into a plurality of blocks as viewed from one irradiation direction A, and the planar positions and planar shapes of the divided first to n-th divided blocks P 1 to Pn, and each divided block The arrangement in the depth direction of P1 to Pn and the target irradiation dose of the proton beam to be irradiated to each of the divided blocks P1 to Pn are associated with each other and data-set. Note that the arrangement information in the depth direction of each of the divided blocks P1 to Pn includes information such as the depth of the deepest portion, the depth of the shallowest portion, and the maximum thickness in the depth direction of the divided blocks. Although FIG. 4 shows an example where the number of divided blocks n = 4, n can be set to an arbitrary number.

  In the irradiation operation of the apparatus 1, the irradiation control unit 17 reads information on the plane position and the plane shape of the first divided block P1 stored in the tumor map 19, drives the multi-leaf collimator 15, and drives the first divided block P1. The opening 15c of the multi-leaf collimator 15 is formed at a planar position and a planar shape corresponding to. Thus, the planar position and planar shape of the irradiation field that slightly spreads outward from the contour of the first divided block P1 are set. Furthermore, the irradiation control unit 17 drives the fine degrader 9 so that the maximum reachable depth of the proton beam reaches a position slightly deeper than the deepest part P1a of the first divided block P1 read from the tumor map 19. To do.

  Further, the irradiation control unit 17 reads information on the maximum thickness k in the depth direction in the first divided block P1 of the tumor P from the tumor map 19, and the SOBP width of the proton beam is slightly larger than the maximum thickness k. As described above, the ridge filter unit 7 is driven to adjust the SOBP. By the operation of each part as described above, the first divided irradiation field R1 having a shape including the three-dimensional shape of the first divided block P1 of the tumor P is set. Furthermore, the irradiation control unit 17 refers to the tumor map 19 and reads the target irradiation dose to be irradiated to the first divided block P1.

  In this state, when a proton beam from the cyclotron 3 is sent to the proton beam irradiation apparatus 1, the proton beam passes through the elements 5 to 15 of the apparatus 1, and is set as the first split irradiation set as a therapeutic proton beam. The field R1 is irradiated, and the proton beam energy is intensively supplied to the first divided block P1 of the tumor P. At this time, the irradiation control unit 17 receives the monitor signal s1 from the dose monitor 23, thereby monitoring the dose of the proton beam irradiated to the first divided irradiation field R1, and the monitor dose and the target irradiation dose. Comparison with Then, when the dose of the proton beam being monitored reaches the target irradiation dose, the irradiation control unit 17 transmits an electric signal s2 to the cyclotron 3. In the cyclotron 3, ion implantation is stopped in response to the electric signal s2, and proton beam transmission is stopped. By such processing, the first division irradiation field R1 is irradiated with the therapeutic proton beam having the target irradiation dose of the first division block P1 which is defined in advance.

  By the control as described above by the irradiation control unit 17, the dose corresponding to the target irradiation dose to the first divided block P1 is applied to the first divided irradiation field R1 having a shape corresponding to the three-dimensional shape of the first divided block P1 of the tumor P. A proton beam is irradiated. And by repeating such irradiation operation n times for each of the first to n-th divided blocks P1 to Pn, the first to n-th divided irradiation fields R1 to R3 corresponding to the three-dimensional shapes of the divided blocks P1 to Pn. While setting Rn sequentially, the whole tumor can be irradiated with a proton beam.

  Here, for comparison, FIG. 5 shows the positional relationship between the irradiation field Q by the conventional proton beam irradiation apparatus and the tumor P in the patient 51. In this irradiation apparatus, irradiation is performed by setting one irradiation field Q that encompasses the entire tumor P. In this case, since the SOBP width h of the proton beam is uniformly set for the entire tumor P on the basis of the maximum thickness of the tumor P in the irradiation direction A, for example, the SOBP width h is too wide in the portion where the tumor P is thin. As a result, the irradiation field Q greatly spreads to the normal tissue around the tumor P.

  On the other hand, according to the proton beam irradiation apparatus 1 described above, the tumor P is divided into a plurality of divided blocks P1 to Pn when viewed from the irradiation direction A, and the maximum thickness k of the tumor P in each of the divided blocks P1 to Pn is determined. The SOBP width of each of the divided irradiation fields R1 to Rn is appropriately set while using the reference. Therefore, the divided irradiation fields R1 to Rn having the optimum thickness are set for each of the divided blocks P1 to Pn, and the entire irradiation formed by combining these divided irradiation fields R1 to Rn as compared with the prior art. The three-dimensional shape of the field R can be made closer to the three-dimensional shape of the tumor P. As a result, the dose concentration of proton beam irradiation on the tumor P can be improved.

  Moreover, according to the proton beam irradiation apparatus 1, since irradiation is performed with reference to the target irradiation dose in each of the divided blocks P1 to Pn, the proton beam is irradiated to each of the divided blocks P1 to Pn with an optimum dose. can do. Moreover, in this irradiation apparatus 1, since the tumor P is divided into blocks as viewed from one direction of the irradiation direction A, all divided blocks P1 to Pn can be irradiated with one gate, and the treatment time is shortened. be able to. Further, since irradiation can be performed at one gate, the same bolus 13 can be used for irradiation of each of the divided blocks P1 to Pn, and the labor for manufacturing the bolus 13 can be reduced.

  The present invention is not limited to the above embodiment. For example, although the lead scatterer 5 is used as the beam expanding unit for expanding the beam, a magnifying device that expands the beam by magnetic force using a magnet may be used instead. Further, as the peak adjustment filter unit, a range modulator may be used instead of the ridge filter unit 7 in the above embodiment. In the above embodiment, the number of divided blocks n of the tumor P is n = 4. However, if the tumor P is further divided by increasing n, the shape of the tumor P and the shape of the irradiation field R can be made closer. , Dose concentration can be improved. Also, the bolus 13 can be omitted by increasing n. When the bolus 13 is used, the fine degrader 9 can be omitted.

  Further, the arrangement order of the elements 5 to 15 for beam shaping in the apparatus 1 is not limited to the above embodiment, and is appropriately designed in consideration of the arrangement space of each element. For example, the arrangement of the ridge filter unit 7 and the fine degrader 9 of the device 1 may be exchanged. Moreover, in the said embodiment, although this invention is applied to the proton beam irradiation apparatus which irradiates a proton beam, this invention is applicable also to other charged particle beam irradiation apparatuses, such as a carbon beam irradiation apparatus. .

It is a perspective view which shows one Embodiment of the proton beam treatment apparatus with which the proton beam irradiation apparatus which concerns on this invention is applied. It is a perspective view which shows the proton beam irradiation apparatus which concerns on this invention. It is a figure which shows each element which comprises the proton beam irradiation apparatus which concerns on this invention. It is sectional drawing which shows the positional relationship of the irradiation field set by the proton beam irradiation apparatus which concerns on this invention, and a tumor. It is sectional drawing which shows the positional relationship of the irradiation field and tumor which are set with the conventional proton beam irradiation apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Proton beam irradiation apparatus (charged particle beam irradiation apparatus), 5 ... Scattering body (beam expansion part), 7 ... Ridge filter part (peak adjustment filter part), 9 ... Fine degrader (beam energy adjustment part), 13 ... Bolus (compensation filter) 13, 15 ... multi-leaf collimator (shape variable collimator), 17 ... irradiation control unit, 19 ... tumor map (target map), 51 ... patient, P ... tumor (irradiation target).

Claims (4)

In a charged particle beam irradiation apparatus that irradiates an irradiation target with a charged particle beam,
A beam expanding unit that expands the beam of the charged particle beam in a direction orthogonal to an irradiation direction;
A peak adjustment filter unit for adjusting an enlarged Bragg peak of the charged particle beam;
A variable shape collimator that adjusts the planar position and planar shape of the irradiation field of the beam viewed from the irradiation direction;
While the deformable collimator and the drives and the peak adjustment filter unit, sequentially sets each irradiation field which is divided into a plurality as viewed from the irradiation direction of the charged particle beam with overlapping part of the irradiation target, An irradiation control unit for sequentially irradiating each of the irradiation fields with the beam of the charged particle beam from the same irradiation direction;
The irradiation control unit
The peak so as to adjust an enlarged Bragg peak width of the charged particle beam in each of the plurality of irradiation fields on the basis of a maximum thickness of a part of the irradiation target corresponding to each of the irradiation fields divided into a plurality of A charged particle beam irradiation apparatus, wherein the adjustment filter unit is driven . The irradiation control unit
While driving the shape variable collimator to set the planar position and planar shape of the irradiation field,
With respect to the planar position viewed from the same irradiation direction, refer to the target map associated with the arrangement of the irradiation target in the irradiation direction,
The peak adjustment filter unit is driven so as to correspond the length of the irradiation direction of the irradiation field to the length of the irradiation direction of the irradiation target corresponding to the set planar position of the irradiation field. Adjust the enlarged Bragg peak of the charged particle beam,
2. The charged particle according to claim 1, wherein in the target map, a target irradiation dose of the beam at the planar position is further associated with the planar position viewed from the same irradiation direction. X-ray irradiation device.   The charged particle beam irradiation apparatus according to claim 1, further comprising a compensation filter that adjusts a shape of a farthest portion of the irradiation field. A beam energy adjusting unit for adjusting the energy of the beam of the charged quantum beam;
The irradiation control unit refers to the target map, and associates the energy of the beam with a position in the irradiation direction of the irradiation target corresponding to the planar position of the irradiation field set by the shape variable collimator. The charged particle beam irradiation apparatus according to claim 1, wherein the energy adjustment unit is controlled as described above.

Images