JP2001276238A - Radiation energy distribution regulating mechanism and radiation irradiation method and device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a dose distribution reproducing correctly an optional three- dimensional shape without using a correction device prepared for each patient. SOLUTION: A three-dimensional dose distribution is obtained by controlling the amount of radiation absorption in each position in the direction of slits of a variable bolus 42 prepared by a radiation energy absorber and whose amount of radiation absorption is made variable in each position in the direction of slits and scanning a slit-shaped dose distribution formed by a slit collimator 50 and the variable bolus 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation energy distribution adjusting mechanism and a radiation irradiation method and apparatus using the same, and more particularly, to a patient suitable for use in a clinical proton therapy system, for example, a patient. The present invention relates to a radiation energy distribution adjusting mechanism for adjusting the energy distribution of radiation irradiated from outside to an affected part into an arbitrary shape, and a radiation irradiation method and apparatus using the same.

[0002]

2. Description of the Related Art A charged particle is accelerated at high speed and high energy in a vacuum by a particle accelerator, and X-rays generated by this are accelerated.
Electron beam, neutron beam, proton beam, pion beam, heavy ion beam, etc.
External radiation therapy in which gamma rays or the like from a cobalt teletherapy device are radiated percutaneously from the outside of a patient to a lesion has become an important therapy together with surgery in the treatment of solid cancer. In particular, since damage to normal tissues around the affected area can be reduced, the demand is expected to increase further in future medical practice where the quality of life (QOL) of patients is emphasized.

[0003] In the radiation treatment by external irradiation, it is important to avoid the surrounding normal tissues or important organs and to give the affected part an irradiation dose distribution that matches the shape of the affected part as accurately as possible. In proton therapy, as shown in FIG. 1, only the cancerous tissue is covered with the Bragg peak P by utilizing the property that the proton beam incident on the substance gives the maximum dose at the Bragg peak P immediately before stopping. By doing so, we try to realize this ideal.

[0004] In the operation of radiotherapy, as shown in FIG. 2, first, in step 100, an X-ray CT image of an affected part is taken. Based on the captured image, a treatment plan is made in step 110 in consideration of the patient's body contour, affected area, and surrounding vital organs. Based on the number of irradiation portals, the direction, and the radiation intensity determined in this treatment plan, in step 120, selection and processing of a fixing auxiliary tool for finely adjusting the irradiation radiation are performed. Next, in step 130, after the patient is positioned 132, irradiation treatment by irradiation 134 is performed.

FIG. 3 shows the configuration of a radiotherapy system. In this radiotherapy system, radiation generated by a radiation generator 10 such as an accelerator passes through a radiation transport device 12 and is guided to a gantry nozzle 14 for irradiating a patient 8 with radiation. In the gantry nozzle 14, the radiation is adjusted to a uniform energy distribution by the radiation observation / adjustment mechanism 16, and then the radiation energy shape forming mechanism 18
The desired energy distribution to be irradiated to the affected part is adjusted, and this is irradiated from outside the patient 8 toward the affected part. Since the dose distribution in the patient is determined by the energy distribution of the radiation, it is planned in advance in consideration of the shape of the affected part.

That is, radiation obtained from the accelerator, for example, a proton beam, has a narrow beam shape, and its energy (the depth of the Bragg peak P) is constant. On the other hand, cancer tissues have various sizes and complicated shapes, the depth in the body is not constant, and the density of the tissue through which proton beams have to pass is not uniform. Therefore, in order to perform proton beam therapy, the proton beam is expanded to (1) a beam wide enough to irradiate the entire cancer at one time, and (2) its energy is adjusted according to the depth of the cancer. (3) Provide an energy distribution according to the thickness of the cancer so as to uniformly irradiate the entire cancer tissue having a depth, and (4) reduce the unevenness of the cancer contour and the tissue through which the proton beam passes. It is necessary to make appropriate corrections.

Therefore, in the conventional external radiotherapy, in order to compensate for the dose distribution in the patient, the radiation energy shape forming mechanism 18 is used when the skin surface of the irradiation site is not flat or the target to be irradiated is Energy distribution correction devices, such as compensation filters, have been used to compensate for dose distribution distortions when they have an inclination with the skin surface.

The compensating filter may be a wedge filter which is a filter plate used in a conventional radiotherapy, for example, such that a spatial isodose curve of a passed beam has a constant slope, or placed on the skin surface. There are boluses used to flatten the irregularities on the illuminated surface. In recent heavy ion beam therapy, a therapy for creating a patient bolus for reproducing the affected part shape from a plurality of irradiation directions for each patient to be treated has been attempted.

Further, in the mechanism for finally adjusting the radiation to be applied, the energy distribution correcting device and the irradiation field shaping device for shaping an irradiation field by shielding an area irradiated with unnecessary radiation are used at the same time. Is normal.

For high-energy radiation, a block collimator for creating an irregular rectangular irradiation field by shielding unnecessary beam portions, and as shown in FIG. A multi-leaf collimator that can be set in the irradiation field according to the shape of the target to be irradiated by moving a rod-shaped collimator of about several mm to 1 cm. There is a patient collimator or the like that limits an irradiation field to an affected part shape by cutting a plate into the shape. The multi-leaf collimator is becoming standard equipment in recent high energy radiation therapy apparatuses.

Specifically, for example, in proton beam therapy, FIG.
As shown in (1), an energy distribution matching the shape of the irradiation target is formed. That is, the narrow proton beam 20 sent to the gantry nozzle 14 as the irradiation unit is expanded in the lateral direction by a scatterer 22 made of, for example, lead having a thickness of several mm, and expanded into a wide beam 24. I do. When a portion having a relatively uniform energy near the central axis is cut out from the expanded beam 24 that spreads and propagates in a conical shape having the scatterer 22 as a vertex by using a collimator described below, a lower treatment table (shown in FIG. Above), the diameter required for treatment is more than 10 cm
Is obtained.

The expanded beam 24 is a fine degrader 26 for adjusting the maximum depth of the proton beam according to the depth of the treatment target (for example, the tumor 8C in the body of the patient 8).
Is incident on. The fine degrader 26 includes, for example, two wedge-shaped opposed acrylic blocks 26.
a, 26b. The thickness of the portion through which the proton beam passes can be continuously changed by adjusting the overlapping manner of the blocks 26a, 26b. The proton beam loses energy according to the thickness of the material that has passed, and the depth at which it can reach varies.
By adjusting 6, the Bragg peak P shown in FIG. 1 can be adjusted to the depth at which the treatment is required.

The proton beam transmitted through the fine degrader 26 is incident on a ridge filter 28 for providing a distribution ΔP in the energy depth of the proton beam corresponding to the thickness of the tumor 8C. The ridge filter 28 is, for example, a triangular prism-shaped metal rod whose thickness changes stepwise in a staggered manner. Since proton beams passing through portions having different thicknesses produce Bragg peaks P at different depths. By adjusting the width and height of the stairs, they can be superimposed appropriately and the peak width ΔP
Can be expanded.

The proton beam passing through the ridge filter 28 is incident on a block collimator 30 for roughly shaping the planar shape of the proton beam. The reason why the shaping is performed by the block collimator 30 in addition to the final collimator to be described later is to prevent generation of secondary radiation by the block collimator near the patient 8.

The proton beam that has passed through the block collimator 30 is input to a bolus 32, which is, for example, a resin-made irregular filter, and correction is made for the maximum depth of the tumor 8C and the non-uniformity of the tissue. This bolus 32
Is calculated based on the contour line of the tumor 8C and the electron density of the surrounding tissue obtained from, for example, X-ray CT data.

The proton beam having passed through the bolus 32 is incident on a final collimator 34 made of, for example, brass, and is finally adjusted to the contour of the planar shape of the tumor 8C. 8 is irradiated.

FIGS. 6 and 7 show an outline of a conventional radiotherapy using the above-described energy distribution adjusting mechanism. FIG.
Is an example of X-ray irradiation in which a dose distribution D is formed using a wedge filter 33 on the patient's head 8H. FIG.
Is an example of two-beam irradiation of proton beam orthogonally to the liver 8L of the patient. In this example, a patient bolus 32 corresponding to the shape of the affected part of the patient is processed and used to obtain a dose distribution D concentrated on the shape of the affected part. In these two examples, the energy distribution adjusting mechanism is fixed with respect to the irradiation direction.

Further, in the conventional treatment plan, the combination of the above-mentioned energy distribution correcting devices is performed by trial and error based on empirical rules. The same is true for the treatment plan in the heavy ion beam therapy, and improvement of the irradiation method has been desired in order to further improve the treatment effect and the treatment speed.

[0019]

That is, the radiation energy distribution adjusting mechanism of the conventional radiation treatment system has the following problems in terms of treatment efficiency.

(1) Since the irradiation pattern is constituted only by a combination of relatively simple correction tools, there is a large mechanical limitation on irradiation for avoiding a complicated affected part shape or an important organ. In particular, in the case of using a beam having high permeability such as a proton beam or a heavy particle beam, even a multi-leaf collimator cannot be used for a small tumor.

(2) The dose distribution correcting device and the irradiation field shaping device are both fixed at the time of irradiation, and when a different irradiation pattern is to be provided, the correction device must be re-equipped for each irradiation. .

(3) When a correction tool created for each treatment, such as a patient bolus, is used, there is a problem in the time and cost for creating the correction tool.

(4) When a correction tool is prepared for each treatment, the correction tool that has been used once becomes radioactive waste, and it is difficult to handle it when discarding.

The present invention has been made in order to solve the above-mentioned conventional problems, and it is a first object of the present invention to realize a three-dimensional dose distribution according to the shape of a diseased part in a patient without replacing a correction tool. Subject.

A second object of the present invention is to improve the accuracy of radiotherapy and shorten the actual irradiation time to reduce the burden on the patient.

[0026]

According to the present invention, there is provided a radiation energy distribution adjusting mechanism for adjusting the energy distribution of irradiated radiation to an arbitrary shape, wherein a slit collimator for shaping the radiation into a slit shape; A variable bolus made of a radiation energy absorber and having a variable amount of radiation absorption at each position in the slit direction and an absorption amount control unit for controlling the amount of radiation absorption at each position in the slit direction of the variable bolus, The first problem is solved by obtaining a three-dimensional dose distribution by scanning a slit-shaped dose distribution formed by the slit collimator and the variable bolus.

Further, the variable bolus is constituted by a plurality of rod-shaped continuous tone boluses arranged in parallel in the width direction and having a radiation absorption amount that changes substantially continuously in the longitudinal direction. The control means slides each continuous tone bolus independently in the longitudinal direction,
The radiation absorption amount at each position in the slit direction is controlled.

Further, the continuous tone bolus is constituted by a rod-shaped member whose density changes substantially continuously in the longitudinal direction.

Alternatively, the continuous tone bolus includes a wedge-shaped member to realize a continuous tone bolus with a simple configuration.

The end position of the slit collimator is made variable so that a slit of an appropriate length is formed to shield portions other than those required for irradiation.

The present invention has also solved the second problem by irradiating radiation of an arbitrary shape by using the radiation energy distribution adjusting mechanism.

Further, in the same radiation irradiating apparatus, the energy distribution adjusting mechanism for the radiation and a variable bolus in the energy distribution adjusting mechanism may be driven in accordance with a required depth direction arrival dose of the passed radiation. The second problem was also solved by providing a variable bolus driving mechanism, and a scanning mechanism for scanning a slit collimator and a variable bolus in the energy distribution adjusting mechanism to obtain a required three-dimensional dose distribution. Things.

In a similar radiation irradiation apparatus, an energy distribution adjusting mechanism for the radiation including a variable slit collimator, and a variable bolus in the energy distribution adjusting mechanism are adjusted according to a required depth-wise arrival amount of the radiation passing therethrough. A variable bolus drive mechanism for driving the variable slit collimator in the energy distribution adjusting mechanism, a variable slit collimator drive mechanism for driving the end position of the variable slit collimator in accordance with the required planar length of the passed radiation. The second problem is also solved by providing a variable slit collimator in the energy distribution adjusting mechanism and a scanning mechanism for scanning a variable bolus to obtain a required three-dimensional dose distribution.

According to the present invention, an active mechanism that can be variably operated at the time of irradiation is introduced by comparing with a passive irradiation section mechanism using a fixing auxiliary tool for finely adjusting the radiation to be used, which has been conventionally used. The dose distribution in the patient at the time of external irradiation of radiation can be more accurately matched with the shape of the affected part while shortening the entire treatment time from treatment planning to irradiation.

[0035]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In the first embodiment of the radiation energy distribution adjusting mechanism according to the present invention, as shown in FIG. 8, the slit length is set to the maximum planar length required for the radiation instead of the block collimator 30 shown in FIG. A fixed slit collimator 40 fixed accordingly, a variable bolus mechanism 42 replacing the patient bolus 32, and a variable slit collimator replacing the final collimator 34, wherein the slit length is variable according to the planar length of the required radiation. 50.

It should be noted that a multi-leaf collimator, a patient collimator, or the like can be used in combination depending on the treatment grade.

As shown in detail in FIG. 9, the variable bolus mechanism 42 has a plurality of rod-shaped continuous tones arranged in parallel in the width direction and having a radiation absorption amount that changes substantially continuously in the longitudinal direction. Boluses 44A to 44K and bolus drive mechanisms 48A to 48K provided for each continuous tone bolus 44A to 44K, for example, each of which includes a ball screw to slide these independently in the length direction. The bolus drive mechanism allows the irradiation line 41
The amount of radiation absorption at each position in the slit direction corresponding to the above is controlled.

The continuous tone boluses 44A-44K are:
For example, as shown in FIG. 10, it is constituted by a rod-shaped member whose density changes substantially continuously in the longitudinal direction.

The continuous tone boluses 44A-44J are:
As in the modification shown in FIG.
A, 46B, or a single wedge 46 as in another modification shown in FIG. 12, or a fine degrader shown in FIG. 5 as another modification shown in FIG. Like two wedges 46A,
46B, an independent bolus drive mechanism 49A,
This can be realized by sliding at 49B.
Alternatively, a thin plate-shaped absorber having an equal radiation absorptivity may be arranged stepwise.

The variable slit collimator 50 shown in FIG.
As shown in detail in FIG. 4, a pair of end bars 52A, 52B respectively inserted from both sides of the slit 50S and, for example, a ball screw for driving each end bar 52A, 52B in accordance with a required slit opening width. It is configured using slit driving mechanisms 54A and 54B.

As shown in FIG. 8, the bolus driving mechanisms 48A to 48K of the variable bolus mechanism 42 are controlled by a variable bolus control device 60, and the slit driving mechanisms 54A and 54B of the variable slit collimator 50 are controlled by a variable slit collimator control device. The gantry nozzle 14 is controlled by a gantry controller 64, and the patient bed 9 is controlled by a patient bed controller 66.

Further, the variable bolus control device 60, the variable slit collimator control device 62, the gantry control device 64, and the patient bed control device 66 are connected to the variable bolus mechanism 42 and the variable slit The adjustment of the collimator 50 and the movement of the gantry nozzle 14 and the patient bed 9 are controlled by the output of the irradiation planning device 72 that calculates a plan for irradiating the divided targets.

Here, attention is paid only to the energy lines or energy peaks of the irradiated radiation, and this is represented as an energy distribution. When the radiation uniformly enters the entire portion of the continuous tone bolus from the vertical direction, a gradient of the energy distribution in the depth direction is generated between the low radiation absorption rate side and the high radiation absorption rate side as shown in FIG. . The radiation that has passed through the continuous tone bolus 44 generates a dose distribution according to the energy distribution after entering the patient.

Therefore, when the irradiation target is linear, by positioning the continuous tone bolus 44 in the horizontal direction, the linear energy distribution in the depth direction, that is, the target dose distribution is changed to the continuous tone bolus. It can be arbitrarily determined within the range of the difference between both ends of the bolus. Further, in the variable bolus mechanism 42 used in the present embodiment, the continuous tone boluses 44A to 44A
The slide-type continuous tone boluses arranged in parallel with each other in combination with 44K are independently moved. When the slide-type continuous tone boluses arranged in parallel are arranged in a pre-planned pattern as shown in FIG. 8, the incident radiation becomes the radiation energy distribution E including the planned portion after passing through the bolus group. Form. If the radiation after passing through the bolus is passed by the variable slit collimator 50 only through the planned portion used for the actual irradiation, the radiation energy distribution after passing through the collimator finally results in the dose distribution planned after the irradiation. Produces D. This dose distribution D is adjusted in advance by a treatment plan so as to conform to the shape of the affected part.

Alternatively, an irradiation pattern optimized based on a certain evaluation criterion is used.

Here, the evaluation criteria include the dose in the target, its uniformity, the influence on the surrounding normal tissue, DVH (do
A result based on se volume histogram) can be considered. Note that each of the irradiation patterns obtained by the optimization does not necessarily need to directly correspond to a part of the target shape.

If the shape of the affected part changes smoothly,
By scanning a linear target dose distribution created by one irradiation while continuously changing the target dose distribution in the horizontal direction as shown in FIG. 15, a target dose distribution forming an arbitrary three-dimensional curved surface is obtained. This scan passes from the initial position of the gantry nozzle 14 having the variable bolus mechanism 42 and the dose distribution D1 formed by the bolus pattern thereof to the intermediate gantry position and the dose distribution D2, and to the final gantry position and the dose distribution D3. This can be realized by moving the gantry nozzle 14 while smoothly changing the bolus. The same effect can be achieved by fixing the gantry nozzle 14 and moving the patient bed 9 or moving both.

The shape of the dose distribution given by one irradiation, which is determined by the plan, may directly correspond to a part of the target shape, or may be made to coincide with the target shape by superimposing a plurality of irradiations. You may.
In the latter case, the shape of the dose distribution given for each irradiation does not necessarily have to coincide with a part of the target shape.

Here, an example of treatment in the case where the shapes match each time will be described.

As shown in FIG. 16, target shape data and a manual division or automatic division algorithm are input to the irradiation planning device 72 from the operation terminal 70.

The irradiation planning device 72 is operated by the operation terminal 70.
A target shape data storage memory 74 for storing target shape data input from the target device, a target shape data input from the target shape data storage memory 74, and a target division or automatic division algorithm input from the operation terminal 70. Three-dimensional dividing device 76 for three-dimensionally dividing the target,
Division target projection shape calculation device 7 for calculating the projection shape of the division target based on the output of the dimension division device 76
8 and a variable slit which outputs a signal for driving the end bars 52A and 52B of the variable slit collimator 50 to the variable slit collimator control device 62 so as to have a required slit length based on the output of the divided target projected shape calculation device 78. A collimator pattern output device 80, an irradiation energy pattern calculation device 82 that determines the irradiation energy distribution of the divided targets based on the output of the target three-dimensional splitting device 76, and an output of the irradiation energy pattern calculation device 82 A variable bolus pattern output device 84 that outputs a signal for driving the bolus driving mechanisms 48A to 48J to the variable bolus control device 60 and an output of the target three-dimensional dividing device 76 so that a required bolus pattern can be obtained. Based on the gantry nozzle 14 and patient base A scan pattern computing device 86 for computing the scanning pattern of bets 9, the scanning pattern computing apparatus 86
Gantry nozzle 14 and patient bed 9 based on the output of
And a gantry / patient bed movement data output device 88 which outputs the movement data of the gantry and the patient bed control device 66.

Referring to FIG. 17, the procedure of the radiation treatment operation using the above embodiment will be described.

First, irradiation data calculation processing 2 in a treatment plan
At 00, the three-dimensional affected part shape restored from the X-ray CT image is read at step 210, and divided at step 220 into several regions corresponding to the number and direction of irradiation gates. For one of the divided regions, a three-dimensional curved surface viewed from the irradiation direction becomes a target dose distribution.

Next, in step 230, the curved surface information is discretized into curve information that changes along a certain axis in accordance with the servo performance and the gantry speed of the bolus driving mechanisms 48A to 48K. Calculate bolus pattern movement data to interpolate. Further, in step 250, the irradiation field length in the direction orthogonal to the gantry moving direction is calculated as a collimator pattern, and in step 260
To calculate gantry movement data.

Next, before proceeding to the actual irradiation, the process proceeds to the alignment processing 300, in which the gantry position is read in step 310, the position of the patient is read in step 320, and the initial position of the gantry is calculated in step 330.

Next, in step 340, the gantry is moved to the initial position, and in step 350, the bolus pattern is set to the initial position.

In the irradiation process 400, irradiation is started in step 410 based on the calculated data.
At step 420, the minimum unit partial irradiation (position measurement, bolus pattern change, collimator adjustment, gantry movement)
Then, the bolus pattern, the variable collimator,
While moving the gantry, irradiation is performed so as to connect between discrete curves that are the minimum unit. After the completion of the irradiation, the irradiation is stopped in step 440.

In the present embodiment, a bolus driving mechanism and a slit driving mechanism are provided to automate the driving of the continuous tone bolus and the end bar. It is not necessary to manually replace the replaced correction tool, and the irradiation direction can be changed quickly, so that a treatment with a small burden on the patient can be performed. Note that the continuous tone bolus and the end bar can be manually moved in and out.

In this embodiment, since the fixed slit collimator 40 is provided above the variable bolus and the variable slit collimator 50 is provided below, the generation of unnecessary secondary radiation can be minimized. . If the generation of secondary radiation is not a problem, the fixed slit collimator 40 is omitted and the variable slit collimator 5 is omitted.
It can be only 0. If the planar length of the irradiated radiation does not matter, it is possible to use a fixed slit collimator having a maximum aperture width instead of the variable slit collimator 50.

In the above embodiment, the present invention is applied to the proton beam therapy system. However, the present invention is not limited to this. The radiotherapy system other than the proton beam, or a general radiation irradiation system is used. It is clear that the same can be applied to the above.

[0062]

According to the present invention, an arbitrary radiation irradiation pattern that matches a complicated affected part shape can be accurately realized by combining radiation energy absorbing materials having simple shapes.

Therefore, as compared with the conventional treatment plan using a fixing mechanism such as a wedge filter, a dose distribution that reproduces a complicated three-dimensional shape can be realized. In terms of treatment is high.

Further, in high-energy radiation therapy, time for creating a bolus for each patient is not required, and the waiting time until a patient bolus is created can be reduced, thereby speeding up the entire treatment. Therefore, the permissible range for changing the irradiation time per unit time is greatly increased, and a more advanced treatment plan is possible.

In addition, no waste material as radioactive waste such as a correction tool created for each patient is generated, and there is no problem of disposal processing.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle of proton beam therapy.

FIG. 2 is a flowchart showing a general radiotherapy operation procedure;

FIG. 3 is a block diagram showing an example of the radiotherapy system.

FIG. 4 is a plan view showing a configuration of a multi-leaf collimator conventionally used as a block collimator.

FIG. 5 is a perspective view showing the principle of energy distribution adjustment and irradiation field formation in proton beam therapy.

FIG. 6 is a cross-sectional view of the brain showing an outline of radiation therapy using a conventional energy distribution correcting device.

FIG. 7 is a sectional view of the same liver part.

FIG. 8 is a perspective view, including a partial block diagram, showing a configuration of an embodiment of an energy distribution adjusting mechanism according to the present invention.

FIG. 9 is a plan view showing the configuration of a variable bolus mechanism used in the embodiment.

FIG. 10 is a perspective view showing the configuration and operation of a continuous tone bolus.

FIG. 11 is a perspective view showing a modification of the continuous tone bolus.

FIG. 12 is a perspective view showing another modification of the continuous tone bolus.

FIG. 13 is a perspective view showing still another modified example of the continuous tone bolus.

FIG. 14 is a plan view showing a configuration of a variable slit collimator used in the embodiment.

FIG. 15 is a perspective view showing a state in which irradiation is performed while moving the gantry for explaining the operation of the embodiment.

FIG. 16 is a block diagram showing a configuration of an operation terminal and an irradiation planning device used in the embodiment.

FIG. 17 is a flowchart showing a procedure of a radiotherapy operation using the embodiment.

[Explanation of symbols]

Reference Signs List 8 ... Patient 8C ... Tumor 8H ... Head 8L ... Liver 9 ... Patient bed 10 ... Radiation generator 12 ... Radiation transport device 14 ... Gantry nozzle 16 ... Radiation observation / adjustment mechanism 18 ... Radiation energy shape forming mechanism 40 ... Fixed slit collimator 41 ... irradiation line 42 ... variable bolus mechanism 44,44A-44J ... continuous tone bolus 48,48A-48J, 49A, 49B ... bolus drive mechanism 46,46A, 46B ... wedge 50 ... variable slit collimator 50S ... slit 52 ... operation Terminals 54A, 54B Slit driving mechanism 60 Variable bolus control device 62 Variable slit collimator control device 64 Gantry control device 66 Patient bed control device 70 Operation terminal 72 Irradiation planning device

Claims (8)

[Claims] 1. A radiation energy distribution adjusting mechanism for adjusting the energy distribution of irradiated radiation to an arbitrary shape, wherein the radiation energy distribution adjusting mechanism is formed by a slit collimator for shaping the radiation into a slit shape, and a radiation energy absorber. A variable bolus in which the radiation absorption amount at each position in the slit direction is variable; and an absorption amount control means for controlling the radiation absorption amount at each position in the slit direction of the variable bolus, formed by the slit collimator and the variable bolus. A three-dimensional dose distribution is obtained by scanning the slit-shaped dose distribution. 2. The variable bolus is composed of a plurality of rod-shaped continuous tone boluses arranged in parallel in the width direction and having a radiation absorption amount that changes substantially continuously in the longitudinal direction.
2. The radiation absorption amount at each position in the slit direction by controlling the absorption amount control means to slide each continuous tone bolus independently in the longitudinal direction. 3. An energy distribution adjusting mechanism for radiation according to claim 1. 3. The radiation energy distribution adjustment according to claim 2, wherein said continuous tone bolus is constituted by a rod-shaped member whose density changes substantially continuously in the longitudinal direction. mechanism. 4. The radiation energy distribution adjustment mechanism according to claim 2, wherein said continuous tone bolus includes a wedge-shaped member. 5. The radiation energy distribution adjusting mechanism according to claim 1, wherein an end position of said slit collimator is variable. 6. A radiation irradiating method comprising irradiating radiation of an arbitrary shape using the radiation energy distribution adjusting mechanism according to any one of claims 1 to 5. 7. A radiation irradiating apparatus for irradiating radiation of an arbitrary shape, wherein the radiation energy distribution adjusting mechanism according to any one of claims 1 to 5, and a variable bolus in the energy distribution adjusting mechanism are: A variable bolus driving mechanism for driving the radiation in accordance with a required depth direction arrival dose of the passed radiation, and a slit collimator and a variable bolus in the energy distribution adjusting mechanism are scanned to obtain a required three-dimensional dose distribution. A radiation irradiation apparatus, comprising: a scanning mechanism; 8. A radiation irradiating apparatus for irradiating radiation of an arbitrary shape, wherein a radiation energy distribution adjusting mechanism according to claim 5, and a radiation passing through a variable bolus in the energy distribution adjusting mechanism are required. A variable bolus drive mechanism for driving in accordance with the depthwise arrival dose, and an end position of a variable slit collimator in the energy distribution adjusting mechanism in accordance with a required planar length of the passed radiation. A variable slit collimator driving mechanism for scanning a variable slit collimator and a variable bolus in the energy distribution adjusting mechanism to obtain a required three-dimensional dose distribution. Irradiation equipment.