JP2001029489A - Radiation irradiation device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for calculating a plurality of apertures formed by a multi-leaf collimator in various shapes in order to realize a radiation beam having intensity modulation, in a much shorter time than in the related art. I will provide a. Further, an apparatus is provided that minimizes radiation treatment time and reduces radiation leakage. A given two-dimensional radiation intensity distribution is decomposed into one or more two-dimensional radiation distributions. In each of the two-dimensional radiation distributions generated by the decomposition, only the cutoff target cell and the irradiation target cell exist, and the irradiation intensity to the irradiation target cell is uniform. In other words, decomposition is performed so as to satisfy this condition. In addition, each generated 2
Decompose into (sub) segments in the dimensional radiation distribution. The individual (sub) segments generated by the decomposition can be realized by a single arrangement of the multi-leaf collimator 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for determining the order of efficient treatment of radiation irradiation, and more particularly to a method and apparatus for controlling the order of irradiation on an irradiation field to be intensity-modulated.

[0002]

2. Description of the Related Art A radiation irradiation apparatus is widely known and used, for example, as an apparatus for treating various diseases. Irradiation devices typically include a gantry that can pivot about a horizontal axis of rotation. A linear accelerator is provided in the gantry to generate a high energy radiation beam. This high energy radiation beam is, for example, an electron or X-ray beam. In treatment, this radiation beam is applied to one of the patients lying on the isocenter of the gantry rotation.
Pointed on one site.

[0003] In order to control the intensity of the radiation radiated toward the object, a beam shielding device including a plurality of leaves (for example, 50 leaves) such as a multi-leaf collimator is usually used to separate the radiation source from the object. In the trajectory of the radiation beam between them. The beam shielding apparatus defines an irradiation field (irradiation area) on an object to which a prescribed radiation absorption dose is applied. These leaves are positioned to accurately direct the radiation beam at the treatment site, for example, at the tumor shape. That is, normal tissues located around the tumor are protected from irradiation. Even if the openings in the leaves give the correct tumor shape, they can also cause unwanted radiation leakage, albeit in small amounts. This leak occurs between leaves, and is typically about 3%.

FIG. 1 shows a conventional radiation therapy apparatus 2 already existing, which uses a multi-leaf collimator 4, a control unit (not shown) in a housing 9, and a processing unit 100. Have been.
The radiation therapy device 2 includes a gantry 6 that can pivot about a horizontal rotation axis 8. The multi-leaf collimator 4 is installed on a protruding portion of the gantry 6 (for example, an accessory holder). A linear accelerator is provided in the gantry 6 to generate the high intensity radiation required for the treatment. The axis of the radiation beam emitted from the linac and gantry 6 is designated as 10. Electronic,
Photons, or other radiation, are used for treatment. During irradiation, the radiation beam is directed onto a site 12 of an object 13 (eg, a patient lying at the center of rotation or isocenter of gantry rotation). Preferably, the axis of rotation 8 of the gantry 6, the axis of rotation 14 of the object to be processed, and the beam axis 10 all intersect at the isocenter.

[0005] The area of irradiation on the patient is known as the irradiation field. The multi-leaf collimator 4 partially blocks radiation. It is provided between the radiation source and the patient to define the radiation beam approximately in the shape of the field. Thus, healthy tissue will receive as little and as much favorable radiation as possible. The radiation treatment device 2 also includes a central processing or control unit 100, which is usually provided separately from the gantry 6 and the housing 9. The processing unit 100 includes at least one output unit such as a display unit or monitor 70 and an input device such as the keyboard 19. The data is also stored in the computer 1 including the data storage device.
8 can be entered. That is, the processing unit 100 is typically operated by a technician or treating physician to perform the radiation treatment prescribed by the treating physician. Using the keyboard 19 or other input device, the technician enters data defining the radiation dose to be delivered to the patient into the control unit of the processing unit 100.

FIG. 2 shows a part of the radiation treatment apparatus 2 and a part of the processing unit 100 in more detail. The electron beam 1 is generated in an accelerator 20. The accelerator 20 includes a gun 21, a waveguide 22, and a vacuum envelope or guide magnet 23. The trigger device 3 generates injection trigger signals and supplies them to the injector 5. Based on these injection trigger signals, the injector 5 generates an injection pulse which is supplied to a gun 21 in the accelerator 20 to generate the electron beam 1. The electrons used to generate the radiation beam are accelerated and guided by a waveguide 22. For this purpose, a high-frequency source is provided, which supplies a radio-frequency signal for generating an electromagnetic field in the waveguide 22.

The electrons injected by the injector 5 and generated by the gun 21 are accelerated by this electromagnetic field in the waveguide 22 and, at the end facing the gun 21, are extracted as electrons which generate radiation. These electrons then enter the guide magnet 23 and are guided therefrom along the axis 10. After passing through the target 15, the electrons generate radiation and the beam passes through the passage of the shield block 50. Next, the beam passes through the ion chamber 60, where the irradiation dose is confirmed.

Finally, a multi-leaf collimator 4 is provided in the radiation beam passage area. As shown in FIG. 19 (2), the multi-leaf collimator 4 includes a plurality of pairs of leaves 41 and 42 arranged in parallel. Leaf 4
1, 42 are driven left and right in FIG. Usually, a rectangular block collimator is orthogonally arranged on the radiation source side of the multi-leaf collimator 4. The block collimators 59 and 61 shown in FIG. 2 are driven in the same direction as the leaves 41 and 42 of the multi-leaf collimator 4. Although not shown, a pair of rectangular block collimators that move in a direction perpendicular to the block collimators 59 and 61 may be provided.

The multi-leaf collimator 4 is driven by a drive unit 43 to change the size of the irradiation field. The drive unit 43 includes the leaves 41 and 42
And an electric motor (not shown) connected to the motor controller 40. The electric motor is controlled by a motor controller 40. To sense the positions of the leaves 41, 42, position sensors 44, 45 are also connected to the respective leaves 41, 42. The motor controller 40 is connected to an irradiation dose control unit 61 including a dose measurement controller, and further connected to the computer 18 for setting a predetermined dose value. The irradiation dose is measured by the ion chamber 60 described above. In response to the deviation between the set value and the actual value, the radiation dose control unit 61 supplies a signal to the trigger device 3 which determines the deviation between the set value and the actual value of the radiation beam output. Change the pulse repetition frequency to minimize it.

It is known that high-dose regions can be generated inside an arbitrary-shaped tumor volume while the intensity of the radiation beam is modulated and used for treatment, while avoiding damage to normal tissue surrounding the tumor. For this purpose, a plurality of apertures formed by a multi-leaf collimator are set in various shapes, and a radiation beam may be overlapped and irradiated a plurality of times by using them, before the application of JP-A-10-71214. , Was widely known for academic papers in this field. JP-A-10-712
The novel content of No. 14 is that the optimization for minimizing the number of different opening shapes is performed by an optimization method such as simulated annealing. JP-A-10-
In Japanese Patent No. 71214, the entire irradiation field is divided into one or a plurality of rectangular sections, a radiation beam intensity map of each section is quantized to form a matrix, and a plurality of openings are set from the matrix. The above-described optimization technique is used when setting a plurality of openings having different shapes.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to set a plurality of apertures formed by a multi-leaf collimator in various shapes in order to realize a radiation beam having intensity modulation. And a device for implementing the method. It is also an object of the present invention to provide a device that minimizes radiation treatment time and reduces radiation leakage.

[0012]

SUMMARY OF THE INVENTION The present invention is a radiation irradiating apparatus and method for achieving the above object. The radiation irradiating apparatus according to the first invention provides a minimum value Aij of Aij for each element Aij of a given two-dimensional radiation intensity distribution matrix.
When min is not approximately 0, means for irradiating the entire irradiation field with the minimum value Amin and a matrix Bij such that Bij = Aij-Amin are set, and the maximum value of Bij (Bijma
x) is 6 or an approximate value of 6, and Bijmax and each B
A means for determining the relative intensity Bnorm ij of each Bij from the ratio with respect to ij, and a matrix Cij in which α is 2.5 or an approximate value of 2.5 and Cij = Bnorm ij−α is set, and 0 Means for irradiating the above elements with a relative intensity of 3 or an approximate value of 3 and setting the residual matrix after irradiation to C * ij, β being an approximate value of 1.5 or 1.5, and Dij = C
means for setting a matrix Dij that satisfies * ij-β, irradiating elements 0 or more with an approximate value of relative intensity 2 or 2 and setting the residual matrix after irradiation to D * ij, Alternatively, a matrix Eij that is an approximate value of 0.5 and Eij = D * ij−γ is set, and relative intensity 1
Or means for irradiating with an approximate value of 1.

The radiation irradiating apparatus according to the second invention irradiates the element Aij of the given two-dimensional radiation intensity distribution matrix with the minimum value Amin when the minimum value Amin of the Aij is not approximately zero. Means for illuminating the entire field, and Bij = Ai
A matrix Bij that is j-Amin is set, and
Means for determining the relative intensity Bnorm ij of each Bij from the ratio of Bijmax to each Bij, with the relative intensity of the maximum value (Bijmax) being 10 or an approximate value of 10; A matrix Cij that is an approximate value and Cij = Bnorm ij-α is set, and elements having 0 or more are irradiated with an approximate value of relative intensity 4 or 4, and the residual matrix after irradiation is C * ij. Means and a matrix Dij in which β is 2.5 or an approximate value of 2.5 and Dij = C * ij−β is set, and an element having a relative intensity of 3 or an approximate value of 3 is set for 0 or more elements. Means for irradiating and setting the residual matrix after irradiation to D * ij, and γ is 1.5 or an approximate value of 1.5, and Eij = D
* ij-γ is set as a matrix Eij, and elements having 0 or more are irradiated with an approximate value of relative intensity 2 or 2 and the residual matrix after irradiation is set as E * ij. Alternatively, a matrix Fij that is an approximate value of 0.5 and that satisfies Fij = E * ij−δ is set, and a relative intensity of 1 is set for 0 or more elements.
Or means for irradiating with an approximate value of 1.

The radiation irradiating apparatus according to the third invention irradiates the element Aij of the given two-dimensional radiation intensity distribution matrix at the minimum value Amin when the minimum value Amin is not approximately zero. Means for illuminating the entire field, and Bij = Ai
A matrix Bij that is j-Amin is set, and
Means for determining the relative intensity Bnorm ij of each Bij from the ratio of Bijmax to each Bij, with the relative intensity of the maximum value (Bijmax) being 3 or an approximate value of 3.
A matrix Cij is set, which is an approximate value of 5 and satisfies Cij = Bnorm ij−α.
Or irradiate with an approximate value of 2 and calculate the residual matrix after irradiation as C
* ij, and a matrix Dij where β is 0.5 or an approximate value of 0.5 and Dij = C * ij−β is set, and relative intensity 1 or 1 is set for 0 or more elements. Means for irradiating with an approximate value of

According to a fourth aspect of the present invention, there is provided a method for irradiating radiation in a radiation irradiating apparatus, wherein a minimum value Ami of Aij is given for each element Aij of a given two-dimensional radiation intensity distribution matrix.
a step of irradiating the entire irradiation field with the minimum value Amin when n is not approximately 0; setting a matrix Bij such that Bij = Aij-Amin; and further setting a maximum value of Bij (Bijmax)
Is set to 6 or an approximate value of 6, and Bijmax and each Bijmax
Obtaining a relative intensity Bnorm ij of each Bij from the ratio of α, and α is 2.5 or an approximate value of 2.5,
Set a matrix Cij such that Cij = Bnorm ij−α,
Irradiating at least 0 elements with a relative intensity of 3 or an approximate value of 3 and setting the residual matrix after irradiation to C * ij;
Is 1.5 or an approximate value of 1.5, and Dij = C * ij-
setting a matrix Dij that becomes β, irradiating elements with 0 or more with an approximate value of relative intensity 2 or 2 and setting the residual matrix after irradiation to D * ij; 5
And a matrix Eij that satisfies Eij = D * ij-γ is set, and relative intensity 1 or 1 is set for 0 or more elements.
And irradiating with an approximate value of

According to a fifth aspect of the present invention, there is provided a method for irradiating radiation in a radiation irradiating apparatus, wherein a minimum value Ami of Aij is given for each element Aij of a given two-dimensional radiation intensity distribution matrix.
a step of irradiating the entire irradiation field with the minimum value Amin when n is not approximately 0; setting a matrix Bij such that Bij = Aij-Amin; and further setting a maximum value of Bij (Bijmax)
Is set to 10 or an approximate value of 10, and the relative intensity Bnorm ij of each Bij is obtained from the ratio between Bijmax and each Bij.
And setting a matrix Cij such that α is an approximate value of 3.5 or 3.5 and Cij = Bnorm ij−α, and an approximate value of relative intensity 4 or 4 with respect to 0 or more elements And irradiating the residual matrix after irradiation with C * ij, β is 2.5 or an approximate value of 2.5, and Dij = C
setting a matrix Dij that satisfies * ij-β, irradiating elements 0 or more with an approximate value of relative intensity 3 or 3 and setting the residual matrix after irradiation to D * ij; Alternatively, a matrix Eij that is an approximate value of 1.5 and Eij = D * ij−γ is set, and a relative intensity of 2
Or, irradiate with an approximate value of 2 and calculate the residual matrix after irradiation as E
* ij, and a matrix Fij in which δ is 0.5 or an approximate value of 0.5 and Fij = E * ij−δ is set, and a relative intensity of 1 or 1 is set for 0 or more elements. And irradiating with an approximate value of

According to a sixth aspect of the present invention, there is provided a method for irradiating radiation in a radiation irradiating apparatus, wherein a minimum value Ami of Aij is given for each element Aij of a given two-dimensional radiation intensity distribution matrix.
a step of irradiating the entire irradiation field with the minimum value Amin when n is not approximately 0; setting a matrix Bij such that Bij = Aij-Amin; and further setting a maximum value of Bij (Bijmax)
Is set to 3 or an approximate value of 3, and Bijmax and each Bij
Calculating a relative intensity Bnorm ij of each Bij from the ratio of: and α is 1.5 or an approximate value of 1.5,
Set a matrix Cij such that Cij = Bnorm ij−α,
Irradiating at least 0 elements with a relative intensity of 2 or an approximate value of 2 and setting the residual matrix after irradiation to C * ij;
Is 0.5 or an approximate value of 0.5, and Dij = C * ij-
setting a matrix Dij that becomes β and irradiating 0 or more elements with a relative intensity of 1 or an approximate value of 1.

A radiation irradiation apparatus according to a seventh aspect of the present invention provides a two-dimensional radiation distribution for irradiating with a predetermined relative intensity obtained in any of the first to sixth aspects described above. Means for calculating the maximum value from the number of islands in each row, counting the number of islands where irradiation elements are continuously gathered and bounded by the cut-off region or end, and searching for the above island from the left end for each row Means for including in its own area as long as the island continues in any row, making this a first segment, and calculating the first segment area from the two-dimensional radiation distribution until the calculated maximum value is reached. To i-1 (the above maximum value ≧ i
After sequentially deleting the segment areas up to ≧ 2), the above island is searched from the left end for each row, and as long as the island continues in any row, it is included in its own area and this is set as the i-th segment. Means for performing the calculation and means for arranging the multi-leaf collimator corresponding to the i-th segment (the maximum value ≧ i ≧ 1).

The radiation irradiating apparatus according to an eighth aspect of the present invention provides a two-dimensional radiation distribution for irradiating with a predetermined relative intensity obtained in any one of the first to sixth aspects of the present invention. From the left end, within the rectangular area including all the rows, the illuminating elements of each row are continuously gathered so that the maximum area of the number of islands bounded by the cut-off area or the end is 1 or less so that the maximum area is obtained. Means for setting the rectangular area and setting the area as the first sub-segment; and when the first sub-segment does not cover the whole of the two-dimensional radiation distribution, the j-th (j ≧ 2) sub-segment From the right of the segment to the right until reaching the right end of the irradiation cell of the two-dimensional radiation distribution, the maximum area and the maximum number of islands in each row within the rectangular area including all the rows is 1 or less. To be the above rectangle And means for repeating that the subsegment of the j and area setting, and means for positioning the multi-leaf collimator in response to the sub-segment of the j (j ≧ 1), the.

A radiation irradiation apparatus according to a ninth aspect of the present invention provides a two-dimensional radiation distribution for irradiating with a predetermined relative intensity obtained in any of the first to sixth aspects of the present invention. From the right end, within the rectangular area including all the rows, the irradiation elements of each row are continuously gathered, and the maximum area of the number of islands bounded by the blocking area or the end is set to be the maximum area within a range of 1 or less. Means for setting the rectangular area and setting the area as the first sub-segment; and when the first sub-segment does not cover the whole of the two-dimensional radiation distribution, the j-th (j ≧ 2) sub-segment From the left of the segment to the left until reaching the left end of the irradiation cell of the two-dimensional radiation distribution to the left, within the rectangular area including all the rows, the maximum area and the maximum number of islands in each row are 1 or less. To be the above rectangle And means for repeating that the subsegment of the j and area setting, and means for positioning the multi-leaf collimator in response to the sub-segment of the j (j ≧ 1), the.

The radiation irradiation apparatus according to the tenth aspect of the present invention is characterized in that, in the calculation results of the two sub-segments obtained in the eighth and ninth aspects, two continuous irradiation matrix elements adjacent to the left and right are used. There is further provided means for calculating the number of times assigned to different sub-segments and employing the calculation result of the smaller number.

According to an eleventh aspect of the present invention, there is provided a method for arranging a multi-leaf collimator in a radiation irradiating apparatus, comprising the steps of irradiating a multi-leaf collimator at a predetermined relative intensity obtained in any of the first to sixth aspects. For the two-dimensional radiation distribution, the number of islands bounded by the blocking area or the end where the irradiation elements of each row are continuously collected and counted for each row, and calculating the maximum value from the number of islands in each row, Look for the island from the left end of each row, include it in your territory as long as the island continues in any row, make it the first segment, and repeat the above 2 until the calculated maximum value is reached. From the one-dimensional segment distribution to the i-th segment from the first segment region (the maximum value ≧ i ≧
After sequentially deleting the segment areas up to 2), search for the island from the left end for each row, and include it in your own territory as long as the island continues in any row, and use this as the i-th segment And arranging the multi-leaf collimator corresponding to the i-th segment (the maximum value ≧ i ≧ 1).

According to a twelfth aspect of the present invention, there is provided a method of arranging a multi-leaf collimator in a radiation irradiating apparatus. The method of irradiating with a predetermined relative intensity obtained in any one of the first to sixth aspects of the present invention For the three-dimensional radiation distribution, from the left end of each row, within a rectangular area including all rows,
The rectangular area is set so as to have a maximum area in a range where the irradiation elements of each row are continuously gathered and the maximum value of the number of islands bounded by the cutoff area or the end is 1 or less, and the area is defined as a first area. The sub-segmenting step, and if the first sub-segment does not cover the whole of the two-dimensional radiation distribution, rightward from the j-1 (j ≧ 2) sub-segment, rightward from the two-dimensional radiation distribution. Until the right end of the irradiation cell of the distribution is reached, the rectangular area is set so that the maximum area of the number of islands in each row within the rectangular area including all rows is 1 or less, and the j-th sub-area is set. The steps of repeating the segmenting and arranging the multi-leaf collimator corresponding to the j-th sub-segment (j ≧ 1).

According to a thirteenth aspect of the present invention, there is provided a method for arranging a multi-leaf collimator in a radiation irradiating apparatus, comprising the steps of irradiating with a predetermined relative intensity obtained in any of the first to sixth aspects of the invention. For the three-dimensional radiation distribution, from the right end of each row, within a rectangular area including all rows,
The rectangular area is set so as to have a maximum area in a range where the irradiation elements of each row are continuously gathered and the maximum value of the number of islands bounded by the cutoff area or the end is 1 or less, and the area is defined as a first area. If the first sub-segment does not cover the entire two-dimensional radiation distribution, and if the first sub-segment does not cover the entirety of the two-dimensional radiation distribution, the two-dimensional radiation is directed leftward from the left of the j-1 (j ≧ 2) sub-segment Until the left end of the irradiation cell of the distribution is reached, the rectangular area is set such that the maximum area of the number of islands in each row is 1 or less within the rectangular area including all the rows, and the j-th sub-area is set. The steps of repeating the segmenting and arranging the multi-leaf collimator corresponding to the j-th sub-segment (j ≧ 1).

According to a fourteenth aspect of the present invention, a method for arranging a multi-leaf collimator in a radiation irradiating apparatus is described in the left and right calculation results of the two sub-segments obtained in the twelfth and thirteenth aspects. The method further includes calculating the number of times that two adjacent continuous irradiation matrix elements are assigned to different sub-segments, and employing a calculation result of the smaller number.

According to a fifteenth aspect of the present invention, there is provided a radiation irradiating apparatus corresponding to the tip position of a rectangular block collimator built in the radiation irradiating apparatus and the sub-segment according to any of the eighth to tenth aspects. The movement of the block collimator is controlled so that the tip positions of the multi-leaf collimators arranged at the same position overlap as much as possible on the irradiation beam axis.

The radiation irradiation apparatus according to the sixteenth invention uses the X-ray or the particle beam as the radiation, wherein the radiation irradiation apparatus uses the X-ray or the particle beam as the radiation. It is a radiation irradiation apparatus of the invention.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A radiation irradiation method and apparatus according to the present invention will be described below with reference to the drawings. All the software for realizing the following radiation irradiation flowchart is installed in the computer 18, and the computer 18
Based on the above software, the radiation amount control unit 61 controls the operation of the multi-leaf collimator 4 and the leaves 41 and 42 and the control of the radiation irradiation dose.

The radiation irradiating apparatus 2 provided with the above-mentioned multi-leaf collimator 4 irradiates radiation with reference to a basic segment 80 of radiation irradiation as shown in FIG.
That is, the basic segment 80 is divided into a plurality of n rows and a plurality of m columns to generate (n × m) cells, and each cell is irradiated with radiation of uniform intensity. Here, in the segment 80 of FIG. 3A, the leaves 41 and 42 provided as a pair on the left and right move in the row direction. For example, if the irradiation target is as shown in FIG. 3B, a plurality of leaf pairs 4 of the multi-leaf collimator 4 as shown in FIG.
1, 42 are arranged. In FIG. 3B, only the cells in the third row and third column are irradiation targets.

In the basic segment 80, there are usually a plurality of irradiation target cells. Further, in each irradiation target cell, the irradiation intensity also varies. The intensity of the radiation emitted from the radiation source is the same at a time. Therefore, as shown in Japanese Patent Application Laid-Open No. 10-71214, a plurality of openings formed by the multi-leaf collimator 4 are set in various shapes, and a radiation beam is superposed and irradiated a plurality of times using them. No.

In the present invention, to realize the above operation, the above operation is divided into two stages. << First Stage of the Present Invention >> A given two-dimensional radiation intensity distribution described below is decomposed into one or a plurality of two-dimensional radiation distributions. In each of the two-dimensional radiation distributions generated by the decomposition, only the cutoff target cell and the irradiation target cell exist, and the irradiation intensity to the irradiation target cell is uniform. In other words, decomposition is performed so as to satisfy this condition. << Second Stage of the Present Invention >> Each of the two-dimensional radiation distributions generated in the first stage is further decomposed into (sub) segments. The individual sub-segments produced by the decomposition are
Can be realized. By using all the arrangements of the multi-leaf collimators 4 corresponding to the sub-segments generated by the above two steps, irradiation is performed with the corresponding intensity, and by superimposing them, the entire irradiation is realized.

Embodiment 1 In FIG. 4, according to the present invention,
A method for performing the first step is shown by a flowchart. In FIG. 4, the basic segment 80 is divided into i rows and j columns, and includes (i × j) cells. Here, the radiation intensity at the i-th row and the j-th column (hereinafter referred to as a two-dimensional radiation intensity distribution) is represented as “Aij”. Aij is obtained by a known calculation method as a radiation intensity distribution that gives the minimum value of the evaluation function, using a constraint condition on the internal dose distribution prescribed by the treating physician and an evaluation function representing the therapeutic effect.

Step 102: In the two-dimensional radiation intensity distribution Aij required for the treatment determined by a known calculation method,
If the minimum value Amin of Aij is not approximately 0, first, the entire irradiation field is irradiated with the minimum value Amin.

Step 104: Bij = Aij-Amin. By normalizing the maximum value of Bij to 6 or an approximate value of 6,
get norm ij. That is, the relative intensity of the maximum value of Bij (Bijmax) is set to 6 or an approximate value of 6, and the relative intensity of each Bij, that is, Bnorm ij is obtained from the ratio between Bijmax and each Bij.

Step 106: Cij = Bnorm ij-α
(Α: 2.5 or an approximate value of 2.5). A cell having a relative intensity of 3 or an approximate value of 3 is irradiated to cells having Cij of 0 or more. Let C * ij be the residual matrix after irradiation.

Step 108: Dij = C * ij-β (β:
1.5 or an approximate value of 1.5). Radiation is applied to cells having Dij of 0 or more at a relative intensity of 2 or an approximate value of 2. Let D * ij be the residual matrix after irradiation.

Step 110: Eij = D * ij-γ (γ:
0.5 or an approximate value of 0.5). Radiation is applied to cells having Eij of 0 or more at a relative intensity of 1 or an approximate value of 1.

FIG. 5 shows a specific calculation example. (1) is a two-dimensional radiation intensity distribution Aij required for treatment determined by a known calculation method. After irradiating with the minimum value Amin of Aij according to step 102 in FIG. 4, at step 104 Bij = Aij-Am
The maximum value of in is normalized to 6 and the normalized intensity distribution Bnorm ij
Then, in step 106, Cij = Bnorm ij-2.5, and the cell having Cij of 0 or more is irradiated with a relative intensity of 3. In (2) of FIG. 5, a white cell is a cell irradiated with a relative intensity of 3. Let C * ij be the residual matrix after irradiation at relative intensity 3. That is, C * ij = Bnorm ij−U
3 (Cij). Here, U3 (Cij) is a matrix that is 3 if the corresponding element Cij is 0 or more, and 0 otherwise.

In step 108, Dij = C * ij-1.5
And Irradiation is performed at a relative intensity of 2 to cells whose Dij is 0 or more. In (3) of FIG. 5, a white cell is a cell irradiated with a relative intensity of 2. The residual matrix after irradiation is D * i
j. That is, D * ij = C * ij-U2 (Dij). Here, U2 (Dij) is a matrix that is 2 if the corresponding element Dij is 0 or more, and 0 otherwise. In step 110, a cell having Eij of 0 or more is irradiated at a relative intensity of 1 with Eij = D * ij-0.5. FIG.
In (4), white cells are cells irradiated with relative intensity 1.

The two-dimensional radiation intensity distribution Aij shown in FIG. 5A and the sum of the respective irradiation intensities decomposed into the minimum value Amin and the relative intensities 3, 2, 1 by the calculation method of FIG. FIG. 6 shows the result of superimposing and plotting each row. What is indicated by diamonds and solid lines is the sum of the results calculated by the present invention, and the stars and dotted lines are the original two-dimensional radiation intensity distribution Aij. It can be seen that they match well. When examined in detail, the average value of the difference between them is zero. That is, when the beam intensity distribution calculated by the method of the present invention is applied to the tumor from multiple directions by rotating the gantry, these differences cancel each other out and can be expected to converge to 0 asymptotically.

Embodiment 2 In the above, the case where the irradiation intensity is decomposed into six levels using the relative intensities 3, 2, 1 (or their approximate values) has been exemplified. That is, to form six levels, three levels of 3, 2, and 1 may be added. Needless to say, if the relative intensities 4, 3, 2, 1 are used, it is possible to decompose into 10 levels. In this case, in the flowchart of FIG. 4, step 102 is left as it is, and the subsequent steps are changed as follows. FIG. 10 shows a flowchart thereof.

Step 104 ': Bij = Aij-Amin. By normalizing the maximum value of Bij to 10 or an approximate value of 10, Bnorm ij is obtained. That is, the maximum value of Bij (Bijmax)
The relative intensity of each Bij, that is, Bno, is determined from the ratio between Bijmax and each Bij.
Find rm ij.

Step 106 ': Cij = Bnorm ij-α
(Α: an approximate value of 3.5 or 3.5). A cell having a relative intensity of 4 or an approximate value of 4 is irradiated to cells having Cij of 0 or more. Let C * ij be the residual matrix after irradiation.

Step 108 ': Dij = C * ij-β (β:
2.5 or an approximate value of 2.5). Radiation is applied to cells having Dij of 0 or more at a relative intensity of 3 or an approximate value of 3. Let D * ij be the residual matrix after irradiation.

Step 110 ': Eij = D * ij-γ (γ:
1.5 or an approximate value of 1.5). The cells having Eij of 0 or more are irradiated with radiation at a relative intensity of 2 or an approximate value of 2. Let E * ij be the residual matrix after irradiation.

Step 112 ': Fij = E * ij-δ (δ:
0.5 or an approximate value of 0.5). Radiation is applied to cells having a Fij of 0 or more at a relative intensity of 1 or an approximate value of 1.

Embodiment 3 Similarly, if the relative intensities 2 and 1 are used, it is possible to decompose into three levels, and the calculation step in that case may be similarly changed. FIG.
FIG.

Embodiment 4 Subsequently, (2) in FIG.
(3) A method of realizing the irradiation of the two-dimensional radiation distribution with relative intensities of 3, 2, 1 as in (4) by arranging the multi-leaf collimator 4 a plurality of times, that is, the second step according to the present invention. Will be described with reference to the flowchart of FIG. In the two-dimensional radiation distribution as described above, since it is general that there are a plurality of shielding regions (black regions) for each row, even if irradiation is performed only once with the multi-leaf collimator 4, incomplete irradiation is incomplete. Irradiation may occur.
Therefore, irradiation is performed in a plurality of arrangements. The process of FIG. 7 is executed for the two-dimensional radiation distribution of the relative intensities of (2), (3), and (4) of FIG.

Step 150: First, white cells (irradiation areas) of each row (referred to as a leaf moving direction of the multi-leaf collimator 4) are continuously gathered, and black cells (cutoff areas) or areas bounded by edges (hereinafter, referred to as edges). The number of islands is called for each row, and the maximum value is determined from the number of islands in each row. This maximum value is the required number of irradiation segments (number of irradiations).

Step 152: A white island is searched from the left end for each row, and as long as the island continues in any row, it is included in its own area and is set as the first segment. The positions of the multi-leaf collimator 4 (MLC) are set at both ends of this segment.

Step 154: The first segment area is deleted, and the processing of step 152 is executed to make the second segment. The position of the multi-leaf collimator 4 is set at both ends of this segment.

Step 156: Step 154 is repeated, and when the number of segments calculated in step 150 has been reached, the processing ends.

FIG. 8 shows an example of the arrangement of the leaves 41 and 42 (hatched portions) of the multi-leaf collimator 4. The leaf pairs face each other and move in the horizontal direction. FIG. 9 is an arrangement of the multi-leaf collimator 4 calculated with respect to FIGS. 5 (2), (3), and (4) according to the flowchart of FIG.
The arrangement of the relative intensity 3 in FIG. 5 (2) with respect to the two-dimensional radiation distribution is (1), (2), and (3) in FIG. 9, and FIG.
9 (4), (5) and (6) in FIG. 9 show the arrangement of the relative intensity 2 for the two-dimensional radiation distribution, and FIG. 9 (4) shows the arrangement for the two-dimensional radiation distribution of the relative intensity 1 in FIG. 7),
(8) and (9). In each of FIGS. 9A and 9B, a white area is an irradiation area, and a black area is an area shielded by the multi-leaf collimator 4. For example, the arrangement shown in FIG. 9A can be realized by the multi-leaf arrangement shown in FIG. As described above, based on the flowchart (FIG. 7) according to the fourth embodiment, from the two-dimensional radiation distribution in which only the cutoff target cell and the irradiation target cell exist and the irradiation intensity to the irradiation target cell is uniform, The arrangement of the multi-leaf collimator can be easily obtained.

Next, a method for performing the second step according to the present invention, which is different from the method shown in FIG. 7, will be described with reference to FIGS.
7, will be described with reference to the flowchart of FIG.

FIG. 13A shows an example of a two-dimensional radiation intensity distribution Aij derived by calculation. This is an example in the case of irradiation from the direction 304 in FIG. FIG.
2 is a three-port (three directions) irradiation model for radiation therapy,
For example, 310 is a human body model, 300 is a tumor model, 3
02 is an important organ model such as the spinal cord surrounded by a tumor. Arrows 304, 306, and 308 indicate three directions in which the radiation beam is irradiated. FIG. 13A is displayed in a gray scale, and the intensity to be irradiated increases from black to white. Since the calculation method is publicly known, a detailed description is omitted here. In short, however, the radiation intensity to irradiate an important organ without giving an excessive dose while giving a sufficient dose to the tumor is described. We will determine the distribution and modulate it.

Next, the first embodiment according to the present invention shown in FIG.
FIGS. 13 (b), (c) and (d) show the results of converting the two-dimensional radiation intensity distribution of FIG. 13 (a) into a two-dimensional radiation distribution of relative intensities of 3, 2, and 1 by the method of performing the steps. . FIG. 13 (b),
(c) and (d) show the illumination in white and the shaded area in black.
It is represented by value information. For example, FIG. 13 (d) shows the distribution of cells to be irradiated with radiation having a relative intensity of 1. The cell distribution is decomposed into four sub-segments and FIG.
(a) to (d). Each of FIGS. 14A to 14D shows a cell that can be irradiated by one operation of the multi-leaf collimator 4.

Embodiment 5 FIG. 13 (d) is replaced with FIG.
The calculation for decomposing into four sub-segments in (d) is shown in FIG.
Is carried out according to the flowchart of FIG.

Step 160: The leaf operation direction of the multi-leaf collimator 4 is set to the direction of each row (the horizontal direction in FIG. 14).
And place the matrix. From the left end, in the rectangular area including all the rows, the rectangular area is set to have the maximum area in a range where the maximum value of the number of islands in each row is 1 or less. The area is defined as a first sub-segment. In actual irradiation, the tips of the leaf pairs are arranged from the left and right of the sub-segment.

Step 162: If the first sub-segment does not cover the entire irradiation cell of the two-dimensional radiation distribution, the second sub-segment is shifted rightward from the right of the j-1 (j ≧ 2) sub-segment. Until reaching the right end of the irradiation cell of the three-dimensional radiation distribution, the rectangular area is set so that the maximum area of the number of islands in each row becomes the maximum area within the rectangular area including all the rows is 1 or less. j, and arranging the tips of the leaf pairs from left to right in the subsegment.

The flowchart according to the fifth embodiment (FIG. 1)
By employing the second stage calculation method of the present invention shown in 6), as will be described later, the dose error peculiar to the multi-leaf collimator 4 can be reduced as a result.

Embodiment 6 FIG. Although FIG. 14 is calculated from the left end in FIG. 13D and decomposed into sub-segments, it can be calculated from the right end and decomposed into sub-segments as shown in the flowchart of FIG. Figure 1 shows the result of the decomposition.
It is shown in FIG.

The second stage calculation method of the present invention shown in the flow charts of FIGS. 16 and 17 has the effect of reducing the dose error peculiar to the multi-leaf collimator 4 as a result. This is because, of the white irradiation cells given in FIG. 13D, the irradiation elements vertically adjacent to each other are always irradiated simultaneously. This is because in FIG. 13D, when two vertically adjacent irradiation elements belong to different sub-segments and are separately irradiated twice, the distance between the leaves 41 (42) of the multi-leaf collimator 4 is reduced. This is because it is known that the irradiation of the area below the boundary line becomes too small due to the step shape. FIG. 19A is a cross-sectional view of a part of the multi-leaf collimator 4 taken along a plane perpendicular to the leaf operating direction. As shown in the drawing, the portions where the leaves 41 (42) are adjacent to each other are meshed in a step shape. This is to prevent radiation leakage from a portion where the leaves 41 (42) are adjacent to each other. In the irradiation method of the present invention, a rectangular area including all rows is selected as an irradiation unit, so that two vertically adjacent irradiation elements always belong to the same irradiation sub-segment.

Embodiment 7 FIG. Further, since the irradiation unit (sub-segment) is a rectangular area, the block collimators 59 and 61 located upstream of the multi-leaf collimator 4 in the radiation source direction are driven, as shown in FIG. By controlling the movement by a mechanism (not shown), the unnecessary irradiation dose to the patient can be reduced. As shown in FIG. 20A, the multi-leaf collimator 4
By controlling the drive of the block collimators 59 and 61 located upstream of the beam in accordance with the angle at which the opening is opened, it is possible to suppress the leakage dose.

It should be noted that there is a limit to the position at which the left block collimator 59 can horizontally move to the right beyond the center line (axis). The same applies to the right block collimator 61. Therefore, it may be difficult to make the opening positions of the block collimators 59 and 61 and the multi-leaf collimator 4 always the same. FIG. 20 (2) shows such a situation. FIG.
At 0 (2), it is desirable for the blocking effect that the right block collimator 61 moves to the line B, but remains at the position shown in the figure due to hardware restrictions. Even in this case, the opening position follows the limit, so that a practically sufficient shielding effect can be obtained.

Embodiment 8 FIG. Note that any of the second-stage calculation methods of the present invention shown in the flowcharts of FIGS. 16 and 17 may be used, but two consecutive irradiation matrix elements (cells) adjacent to the left and right are assigned to different sub-segments. It is desirable to calculate the number of times of execution and to adopt the second-stage calculation method with the smaller number of times (FIG. 18).
This is because, when continuous irradiation areas (cells) are allocated to different sub-segments, the optimum position at which the irradiation intensity for the two consecutive cells is uniform is measured by fine-tuning the leaf tip position of the multi-leaf collimator 4 in advance. It is necessary to keep it. For such measurement, it is sufficient to perform test measurement with water or the like as an object in advance and acquire data, but in actual measurement, occurrence of an error due to body movement of the patient cannot be avoided. Therefore, it is reasonable to choose the one that can reduce this possibility.

In any of the above embodiments, the type of radiation is not limited. For example, X-rays or particle beams may be used.

[0067]

According to the first aspect of the present invention, there is provided a radiation irradiation apparatus comprising:
The two-dimensional radiation intensity distribution quantized into two levels is further divided into two-dimensional radiation distributions having relative intensities of 3, 2, and 1. In each of the two-dimensional radiation distributions generated by the decomposition, only the cutoff target cell and the irradiation target cell exist, and the irradiation intensity to the irradiation target cell is uniform. Therefore, after that, only the arrangement of the multi-leaf collimator is considered in accordance with the generated two-dimensional radiation distribution, and radiation irradiation according to a given two-dimensional radiation intensity distribution can be easily realized.

The radiation irradiating apparatus according to the second invention has the first
Similarly to the radiation irradiation apparatus according to the invention, the radiation irradiation according to a given two-dimensional radiation intensity distribution can be easily realized. Furthermore, the radiation irradiation becomes closer to a given two-dimensional radiation intensity distribution than the radiation irradiation apparatus according to the first invention.

The radiation irradiation apparatus according to the third invention has a first
Similarly to the radiation irradiation apparatus according to the invention, the radiation irradiation according to a given two-dimensional radiation intensity distribution can be easily realized. Further, the amount of calculation is smaller than that of the radiation irradiation apparatus according to the first invention.

The method of irradiating radiation in the radiation irradiating apparatus according to the fourth invention is a method of irradiating a two-dimensional radiation intensity distribution quantized to six levels, and further calculating relative intensities 3, 2, 1
Is divided into two-dimensional radiation distributions. In each of the two-dimensional radiation distributions generated by the decomposition, only the cutoff target cell and the irradiation target cell exist, and the irradiation intensity to the irradiation target cell is uniform. Therefore, the generated 2
It is only necessary to consider the arrangement of the multi-leaf collimator according to the two-dimensional radiation distribution, and radiation irradiation according to a given two-dimensional radiation intensity distribution can be easily realized.

According to the method of irradiating radiation in the radiation irradiating apparatus according to the fifth invention, radiation irradiation according to a given two-dimensional radiation intensity distribution can be easily realized, similarly to the radiation irradiating method according to the fourth invention. . Further, the radiation irradiation becomes closer to the given two-dimensional radiation intensity distribution than the radiation irradiation method according to the fourth invention.

According to the method of irradiating radiation in the radiation irradiating apparatus according to the sixth aspect of the present invention, similarly to the radiation irradiating method of the fourth aspect, it is possible to easily realize radiation irradiating according to a given two-dimensional radiation intensity distribution. . Further, the calculation amount is smaller than that of the radiation irradiation method according to the fourth aspect.

The radiation irradiating apparatus according to the seventh aspect of the present invention provides a multi-leaf collimator based on a two-dimensional radiation distribution in which only the target cell to be cut off and the target cell are present and the irradiation intensity to the target cell is uniform. The arrangement can be determined easily.

The radiation irradiating apparatus according to the eighth aspect of the present invention provides a multi-leaf collimator based on a two-dimensional radiation distribution in which only an interruption target cell and an irradiation target cell are present and the irradiation intensity to the irradiation target cell is uniform. The arrangement can be determined easily.

The radiation irradiation apparatus according to the ninth aspect of the present invention provides a multi-leaf collimator based on a two-dimensional radiation distribution in which only the target cell to be cut off and the target cell are present and the irradiation intensity to the target cell is uniform. The arrangement can be determined easily.

According to a tenth aspect of the present invention, there is provided a radiation irradiating apparatus for a multi-leaf collimator based on a two-dimensional radiation distribution in which only an interruption target cell and an irradiation target cell are present and the irradiation intensity to the irradiation target cell is uniform. The arrangement can be determined easily. In addition, the possibility of occurrence of an error due to the patient's body movement or the like can be reduced.

The method of arranging a multi-leaf collimator in a radiation irradiation apparatus according to the eleventh invention has a simple content and requires a small amount of calculation.

The method of arranging a multi-leaf collimator in a radiation irradiation apparatus according to the twelfth invention has a simple content and requires a small amount of calculation.

The method of arranging the multi-leaf collimator in the radiation irradiation apparatus according to the thirteenth invention has a simple content and requires a small amount of calculation.

The method for arranging the multi-leaf collimator in the radiation irradiation apparatus according to the fourteenth invention has a simple content and requires a small amount of calculation. Moreover, at the time of actual radiation irradiation, the possibility of occurrence of an error due to a patient's body movement or the like can be reduced.

The radiation irradiation apparatus according to the fifteenth aspect can reduce the unnecessary irradiation dose to the irradiation target (eg, patient) by suppressing the leakage dose.

The radiation irradiating apparatus according to the sixteenth aspect is characterized in that X
When irradiating a beam or a particle beam, the effects of the first to fifteenth aspects can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a radiation irradiation apparatus according to the present invention.

FIG. 2 is a block diagram of a part of a radiation irradiation apparatus and a processing unit.

FIG. 3 shows a basic segment indicating the position of radiation irradiation,
It is a top view of the example of arrangement of a multi-leaf collimator.

FIG. 4 is one of the flowcharts (Embodiment 1) for performing the first step of the present invention.

FIG. 5 is a calculation example (1) according to the flowchart in FIG. 4 which is the first embodiment.

FIG. 6 is a graph for comparison between a calculation result according to the flowchart of FIG. 4 and a given two-dimensional radiation intensity distribution.

FIG. 7 is a flowchart (Embodiment 4) for performing the second step of the present invention.

FIG. 8 is a plan view of an arrangement example of a multi-leaf collimator.

FIG. 9 is a calculation example according to the flowchart of FIG. 7 which is the fourth embodiment.

FIG. 10 is one flowchart (Embodiment 2) for performing the first step of the present invention.

FIG. 11 is one (third embodiment) of a flowchart for performing the first step of the present invention.

FIG. 12 is a three-way irradiation model for radiation therapy.

13 is a calculation example (2) according to the flowchart in FIG. 4 which is the first embodiment.

FIG. 14 is a calculation example according to the flowchart of FIG. 16 which is the fifth embodiment.

FIG. 15 is a calculation example according to the flowchart of FIG. 17 which is the sixth embodiment.

FIG. 16 is one flowchart (Embodiment 5) for performing the second step of the present invention.

FIG. 17 is a flowchart (Embodiment 6) for performing the second step of the present invention.

FIG. 18 is a flowchart (Embodiment 8) for performing the second step of the present invention.

FIG. 19 is a configuration diagram of a block collimator and a multi-leaf collimator.

FIG. 20 is a side sectional view showing a configuration of a block collimator and a multi-leaf collimator.

[Explanation of symbols]

2 Irradiation (treatment) device, 4 multi-leaf collimator, 6 gantry, 18 computer, 41 leaf, 4
2 leaves, 59 block collimator, 61 block collimator, 80 basic segments, 100 processing units

Claims (16)

[Claims] A means for irradiating the entire irradiation field with the minimum value Amin of each element Aij of a given two-dimensional radiation intensity distribution matrix when the minimum value Amin is not approximately 0; = Aij-Amin is set, and the relative intensity of the maximum value (Bijmax) of Bij is set to 6 or 6
Of each Bij from the ratio of Bijmax to each Bij
Means for determining the relative intensity Bnorm ij provided by: where α is 2.5 or an approximate value of 2.5, and Cij = Bnorm
means for setting a matrix Cij to be ij-α, irradiating elements 0 or more with an approximate value of relative intensity 3 or 3 and setting the residual matrix after irradiation to C * ij, 1.5, Dij = C * ij
Means for setting a matrix Dij that becomes -β, irradiating elements with 0 or more with an approximate value of relative intensity 2 or 2 and setting the residual matrix after irradiation to D * ij, and γ being 0.5 or 0 .5, Eij = D * ij
Means for setting a matrix Eij to be −γ and irradiating 0 or more elements with a relative intensity of 1 or an approximate value of 1. 2. For each element Aij of a given two-dimensional radiation intensity distribution matrix, when the minimum value Amin of Aij is not approximately zero, irradiating the entire irradiation field with this minimum value Amin; = Aij-Amin is set, the relative intensity of the maximum value of Bij (Bijmax) is set to 10 or an approximate value of 10, and the relative intensity Bnorm ij of each Bij is determined from the ratio of Bijmax to each Bij. And α is 3.5 or an approximate value of 3.5, and Cij = Bnorm
means for setting a matrix Cij to be ij-α, irradiating elements with 0 or more with an approximate value of relative intensity 4 or 4 and setting the residual matrix after irradiation to C * ij, 2.5, where Dij = C * ij
Means for setting a matrix Dij that becomes -β, irradiating elements 0 or more with an approximate value of relative intensity 3 or 3 and setting the residual matrix after irradiation to D * ij, and γ being 1.5 or 1 .5, Eij = D * ij
Means for setting a matrix Eij to be −γ, irradiating elements with 0 or more with an approximate value of relative intensity 2 or 2, and setting the residual matrix after irradiation to E * ij, .5, where Fij = E * ij
Means for setting a matrix Fij that becomes −δ and irradiating elements with zero or more with relative intensity of 1 or an approximate value of 1. 3. A means for irradiating the entire irradiation field with a minimum value Amin of each element Aij of a given two-dimensional radiation intensity distribution matrix when the minimum value Amin of the matrix is not approximately 0; = Aij-Amin is set, and the relative intensity of the maximum value (Bijmax) of Bij is set to 3 or 3
Of each Bij from the ratio of Bijmax to each Bij
Means for obtaining the relative intensity Bnorm ij provided by: α is 1.5 or an approximate value of 1.5, and Cij = Bnorm
means for setting a matrix Cij to be ij-α, irradiating elements 0 or more with an approximate value of relative intensity 2 or 2 and setting the residual matrix after irradiation to C * ij, β being 0.5 or 0.5, where Dij = C * ij
Means for setting a matrix Dij to be −β and irradiating 0 or more elements with a relative intensity of 1 or an approximate value of 1. 4. For each element Aij of a given two-dimensional radiation intensity distribution matrix, irradiating the entire irradiation field with the minimum value Amin of Aij if the minimum value Amin is not approximately 0; = Aij-Amin is set, and the relative intensity of the maximum value (Bijmax) of Bij is set to 6 or 6
Of each Bij from the ratio of Bijmax to each Bij
Obtaining a relative intensity Bnorm ij provided by: α is 2.5 or an approximate value of 2.5, and Cij = Bnorm
setting a matrix Cij to be ij-α, irradiating elements with 0 or more with an approximate value of relative intensity 3 or 3 and setting the residual matrix after irradiation to C * ij, β is 1.5 or 1.5, where Dij = C * ij
-Setting a matrix Dij to be -β, irradiating elements with 0 or more with an approximate value of relative intensity 2 or 2 and setting the residual matrix after irradiation to D * ij, and γ being 0.5 or 0 .5, Eij = D * ij
Setting a matrix Eij that becomes -γ, and irradiating the elements with 0 or more with an approximate value of relative intensity 1 or 1 to irradiate the radiation with the radiation irradiating apparatus. 5. For each element Aij of a given two-dimensional radiation intensity distribution matrix, irradiating the entire irradiation field with the minimum value Amin of Aij if the minimum value Amin is not approximately 0; = Aij-Amin is set, the relative intensity of the maximum value of Bij (Bijmax) is set to 10 or an approximate value of 10, and the relative intensity Bnorm ij of each Bij is determined from the ratio of Bijmax to each Bij. And α is 3.5 or an approximate value of 3.5, and Cij = Bnorm
setting a matrix Cij to be ij-α, irradiating the elements 0 or more with an approximate value of relative intensity 4 or 4 and setting the residual matrix after irradiation to C * ij, β is 2.5 or 2.5, where Dij = C * ij
-Setting a matrix Dij that becomes -β, irradiating elements with 0 or more with an approximate value of relative intensity 3 or 3 and setting the residual matrix after irradiation to D * ij, and γ being 1.5 or 1 .5, Eij = D * ij
-Setting a matrix Eij that becomes -γ, irradiating elements with 0 or more with an approximate value of relative intensity 2 or 2 and setting the residual matrix after irradiation to E * ij, and δ being 0.5 or 0 .5, where Fij = E * ij
Setting a matrix Fij that satisfies −δ and irradiating zero or more elements with a relative intensity of 1 or an approximate value of 1 in a radiation irradiation apparatus. 6. For each element Aij of a given two-dimensional radiation intensity distribution matrix, if the minimum value Amin of Aij is not approximately zero, irradiating the entire irradiation field with this minimum value Amin; = Aij-Amin is set, and the relative intensity of the maximum value (Bijmax) of Bij is set to 3 or 3
Of each Bij from the ratio of Bijmax to each Bij
Calculating the relative intensity Bnorm ij provided by: α is 1.5 or an approximate value of 1.5, and Cij = Bnorm
setting a matrix Cij that becomes ij-α, irradiating elements with 0 or more with an approximate value of relative intensity 2 or 2 and setting the residual matrix after irradiation to C * ij, β is 0.5 or 0.5, where Dij = C * ij
Setting a matrix Dij to be -β and irradiating zero or more elements with a relative intensity of 1 or an approximate value of 1 to irradiate the radiation with the radiation irradiating apparatus. 7. With respect to the two-dimensional radiation distribution irradiated at a predetermined relative intensity obtained in any one of claims 1 to 6, the irradiation elements in each row are continuously gathered to form a cut-off area or end. A means for counting the number of islands to be bounded for each row, calculating the maximum value from the number of islands in each row, and searching for the above island from the left end for each row, as long as the island continues in any row, Means for setting the first segment as the first segment, and from the two-dimensional radiation distribution, from the first segment area to the i-th segment (the maximum value ≧ i ≧ 2) until the calculated maximum value is reached. After sequentially deleting the segment areas up to), the above island is searched from the left end for each row, and as long as the island continues in any row, it is included in its own area and this is set as the i-th segment. Means for performing; and the ith segment (above Means for arranging the multi-leaf collimator corresponding to the maximum value ≧ i ≧ 1). 8. With respect to the two-dimensional radiation distribution irradiated at a predetermined relative intensity obtained in any one of claims 1 to 6, in a rectangular area including all rows from the left end of each row, The rectangular area is set so as to have a maximum area in a range where the irradiation elements of each row are continuously gathered and the maximum value of the number of islands bounded by the cutoff area or the end is 1 or less, and the area is defined as a first area. Means for sub-segmenting, if the first sub-segment does not cover the whole of the two-dimensional radiation distribution, the right-hand side of the j-1 (j ≧ 2) sub-segment, the right-hand side of the two-dimensional radiation distribution The rectangular area is set so that the maximum area of the number of islands in each row is equal to or less than 1 in the rectangular area including all the rows until the right end of the irradiation cell is reached. To do Means for Fukusuru, radiation irradiation apparatus and a means for positioning the multi-leaf collimator in response to the sub-segment of the j (j ≧ 1). 9. With respect to the two-dimensional radiation distribution irradiated at a predetermined relative intensity obtained in any one of claims 1 to 6, in a rectangular region including all the rows from the right end of each row, The rectangular area is set so as to have a maximum area in a range where the irradiation elements of each row are continuously gathered and the maximum value of the number of islands bounded by the cutoff area or the end is 1 or less, and the area is defined as a first area. When the first sub-segment does not cover the whole of the two-dimensional radiation distribution, the two-dimensional radiation is moved leftward from the left of the j-1 (j ≧ 2) sub-segment. Until the left end of the irradiation cell of the distribution is reached, the rectangular area is set such that the maximum area of the number of islands in each row is 1 or less within the rectangular area including all the rows, and the j-th sub-area is set. To be a segment Means for repeating, and means for placing a multi-leaf collimator in response to the sub-segment of the j (j ≧ 1), a radiation irradiation apparatus equipped with. 10. The calculation result of the two sub-segments obtained in claim 8 and claim 9, wherein two left and right adjacent sub-segments are calculated.
A radiation irradiation apparatus further comprising: means for calculating the number of times that two consecutive irradiation matrix elements are assigned to different sub-segments, and employing a calculation result of the smaller number. 11. With respect to the two-dimensional radiation distribution irradiated at a predetermined relative intensity obtained in any one of claims 1 to 6, the irradiation elements in each row are continuously gathered to form a cut-off area or an end. Counting the number of islands to be bound for each row, calculating the maximum value from the number of islands in each row, searching for the above island from the left end for each row, and as long as the island continues in any row, The first segment region from the two-dimensional radiation distribution until the calculated maximum value is reached, from the first segment region to the i-1th (the maximum value ≧ i ≧ 2). After sequentially deleting the segment areas up to), search for the above island from the left end for each row, include it in your territory as long as the island continues in any row, and perform an iterative calculation to make this the i-th segment The steps to be performed and the ith segment (above Arranging the multi-leaf collimator corresponding to the maximum value ≧ i ≧ 1) in the radiation irradiation apparatus. 12. With respect to the two-dimensional radiation distribution irradiated at a predetermined relative intensity obtained in any one of claims 1 to 6, in a rectangular area including all rows from the left end of each row, The rectangular area is set so as to have a maximum area in a range where the irradiation elements of each row are continuously gathered and the maximum value of the number of islands bounded by the cutoff area or the end is 1 or less, and the area is defined as a first area. Sub-segmenting; and if the first sub-segment does not cover the entire two-dimensional radiation distribution, rightward from the j-1 (j ≧ 2) sub-segment, rightward from the two-dimensional radiation distribution. The rectangular area is set so that the maximum area of the number of islands in each row is equal to or less than 1 in the rectangular area including all the rows until the right end of the irradiation cell is reached. To do A step of repeating the steps of placing the multi-leaf collimator in response to the sub-segment of the j (j ≧ 1), made of a method of placing the multi-leaf collimator in the irradiation apparatus. 13. With respect to the two-dimensional radiation distribution irradiated at a predetermined relative intensity obtained in any one of claims 1 to 6, in a rectangular region including all the rows from the right end of each row, The rectangular area is set so as to have a maximum area in a range where the irradiation elements of each row are continuously gathered and the maximum value of the number of islands bounded by the cutoff area or the end is 1 or less, and the area is defined as a first area. Sub-segment; and if the first sub-segment does not cover the entire two-dimensional radiation distribution, the two-dimensional radiation is directed leftward from the left of the j-1 (j ≧ 2) sub-segment. Until the left end of the irradiation cell of the distribution is reached, the rectangular area is set such that the maximum area of the number of islands in each row is 1 or less within the rectangular area including all the rows, and the j-th sub-area is set. Segment A step of repeating the bets, placing a multi-leaf collimator in response to the sub-segment of the j (j ≧ 1), made of a method of placing the multi-leaf collimator in the irradiation apparatus. 14. The method according to claim 12, wherein
Calculating the number of times two consecutive irradiation matrix elements adjacent to the left and right are assigned to different sub-segments in the calculation result of one sub-segment, and adopting the calculation result of the smaller number of irradiations. A method of arranging a multi-leaf collimator in an apparatus. 15. The position of the tip of a rectangular block collimator built in a radiation irradiation apparatus, and the position of the block collimator.
A radiation irradiating apparatus that controls the movement of the block collimator so that the tip positions of the multi-leaf collimators arranged corresponding to any one of the sub-segments overlap as much as possible on the irradiation beam axis. 16. The method according to claim 1, wherein X-rays or particle beams are used as radiation.
Alternatively, the radiation irradiation device according to claim 15.