JPS5822072A - Apparatus for limitting radioactive ray irradiation field - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation field limiting device (hereinafter sometimes simply referred to as a diaphragm) in a radiation therapy apparatus.

Conventionally, radiation therapy equipment K is used. As shown in FIG.
, 24), as shown in FIG. 1(6) and c)K, four blocks 2a m 2! -2a e
Of 2d, two opposing pullsku 2hata, 2&(2
g, 24) By driving each of them to move them toward and away from each other on an arc centered on a central axis that includes the radiation source 1 and is parallel to the radiation irradiation field, as shown in FIG. A radiation irradiation field 4t of an arbitrary size is formed according to the shape of the affected area 6. but,
The aperture described in '#I has the following drawbacks. In other words, while the affected area is generally circular or elliptical, the radiation irradiation field 4 is rectangular. Therefore, if an attempt is made to treat the affected area with - times of radiation irradiation, the radiation will reach the healthy tissue K as shown in the JIs diagram. (by being irradiated), healthy tissue suffers radiation damage. Therefore, in order to eliminate this defect,
Kairan 110 to 1 as follows! The 2 m lower boot stock shown in Fig. 1 (4) was used for the improved aperture).
, 2d is divided into a plurality of cheekbone shapes.
A pair of boots 7 located above and facing each other
As shown in Figure 4 (■), the small blocks 4 m, 4, belonging to the small boot block group 6 facing each other, are moved manually or electrically to move them on a horizontal surface. while approaching and separating from each other independently, the upper pushpiece 7a as shown in the 4th mmK.

By driving each of them and moving them toward and away from each other on an arc centered on the radiation source 1, the shape of the affected area 3 is approximated as shown in the diagram.
It is like forming &.

However, even in the above-mentioned revised JllLWi,
There are the following problems. In other words, as shown in JIF611, the small boot black G, which moves horizontally by 1, and the radiation irradiation field width WiBm and Bk of 6 are straight, so the radiation irradiation W limited 1#8g, 84 enters here. Due to the transmitted radiation, a cow's shadow field (Km) is created, and this is a good idea for the radiation irradiation field 4), which is set as shown in Figure 7. Radiation damage to healthy tissues cannot be avoided. This is a serious problem for radiation therapy equipment, which aims to perform effective radiotherapy while minimizing the occurrence of radiation damage. It is.

This invention was made in view of the above-mentioned circumstances, and was made to match the radiation irradiation field (set irradiation field) in the acid chamber with the radiation irradiation W (actual irradiation field) obtained by actually irradiating radiation. The purpose of the present invention is to provide a radiotherapy device KTh that can minimize the occurrence of radiation damage to health and tissues in actual irradiation fields. Please refer to wJWi for an embodiment of this invention.
[As shown in Figure 8, the diaphragm according to the invention 〇
Two opposing sets of 0 small plots I*1j located at lower lll
, 12 are the main ones, and since they face each other, bootsta 10g, 10 & 10 are made of heavy metal, for example, and formed into a rectangular shape.
In order to determine the radiation irradiation field by driving them closer to each other on an arc centered on the central axis parallel to the fringe irradiation field, and then moving away from each other, this plotter 10g, 10&those can use the o4ho which is known per se, so the details thereof will be omitted.Small boot stocks #11 and 12 can be operated in the summer, respectively, as shown in jlI9g. Small boots 13.-ISL are arranged in a manner similar to that for writing and have different shapes.
13g --15m)
5Em! Placed, each small block 13g, 1! &,I
Sa--11@ is a small block 15g, 134-13g that is driven to move on the circumferential side of an imaginary cylindrical body having the radiation source 1 as its center and a center line that meets the radiation source 1. ...= 1
The 3sO shape is as follows. That is, the large and small boots 13g, as shown in the $110 figure, are a hexagonal figure having planes BHIE, AGJF, GHI and FJII. and,
As shown in @101I(2) and e), radiation source 1
(Sometimes indicated as 0 point.) When imagining a cylindrical body U having a central axis 2 including the center axis 2 and a thickness approximately equal to the inner @v and outer diameter, the small boot stock 13 is the center of the imaginary cylindrical body UO. Any OWi that shares axis 2 Zl and 0@Z
, and because they share the central axis 2 and have an angle wet to
Reference 1 it), then a virtual cone 11 having a central angle of -1 with respect to the central axis 2 and having the radiation source 1 (point 0) as its apex & also a central angle #s (lN-
#s>#*), and it also has the same 〇 shape as O, which is obtained by cutting the temporary cylindrical body U with a temporary O conical surface with the radiation source 1 as the apex. Then, in the small block 13, the bay-painting BHIF: is temporary-〇cylindrical body UO
Similarly to a part of the inner circumferential surface, the central axis 2 is a circular arc], and the bay surface AGJF has a part of the outer periphery Wlo of the circular building body U and j411 from the central axis 2 to 41i. In addition, in the small bootsta 13a, it has a curved surface AGHB, a central angle #, and an apex O.
It has the same 〇 curvature as a part of the conical surface with , i ratio, curvature 1
111FJIK has a central angle θ1 and a vertex O
It has the same curvature as the part of the conical surface that has . Komude,
The cow 11r is determined by the distance from the radiation source 1 to the diaphragm position. It can be determined depending on the material of the small boot stock 13- so that the small boot stock 13#0 side BH (II) or side G (FJ)0111!
h should be determined appropriately depending on the side AP (GJ) 0 and the set trajectory field.

The small block 13 can be formed in the same manner as the small block 156, but the differences are as follows. In other words, it has a central angle #1 with respect to the central axis 2 and has the radiation 11111 as its apex. Source 1t-vertex and value Ruo cone II''
e) Cut the imaginary cylindrical body U), set the central angle #1 with respect to the central axis 2 so that the side BE (Hl) of the small block 1h and the side EL (IM) of the small block 13- are equal. A virtual cylindrical body U with a virtual conical surface having the radiation source 1 as its apex and a central angle #(9) with respect to the central axis 2, and a virtual conical surface having the radiation source 1 as the vertex. It is with cutting jin.

The small plotter 13# and below can be configured to have the same relationship as the small block 13# and the small block 13s.〇Small plotter 15m-15hA5m=-15s O arrangement has a constant center with respect to the central axis ZK. Each block 13a, 136.13g --15s has an angle θ1 and the radiation *wi is the vertex, so that they share a virtual conical surface with each other.
Try to place O-m first.

The drive of each small plotter 13g, 13L13-2-13s- can be carried out appropriately by the O method, for example, by combining a rack provided on a small plotter with a pinion to mesh with the rack. Gade self @ each car bootsta 13g,
131 =-.13s has the structure described in detail above, so for example, the small block 13a has a central angle #1 with respect to the central axis 2, and a virtual conical surface with the radiation source 1 as the apex, the central axis Move the space surrounded by the virtual conical surface and the inner and outer circumferential surfaces of the virtual cylindrical body UO, which have a central angle #2 with respect to 2 and have the radiation source 1 as the apex, in the Y direction in Fig. 10 Q. Moreover, even if the small block is moved in this way, the small block 1kO plane ABEF (definition of the radiation field) forms part of the plane that includes the central axis 2.
The generation of a radiation penumbra can be prevented, and the ΔG small block 13 & below also exhibits the same effect as the small block 13.

Although one embodiment of the present invention has been described above in detail, the present invention is not limited to the above-mentioned embodiment, and may include various modifications without changing the gist of the invention. As a modification, for example, K as shown in Figure 811.

Each small plotter 14M, 146 that constitutes a small block IP
In..., a four-striped groove 15- is formed on the curved surface of - which forms a part of the conical surface, and a four-striped groove 15- is formed on the curved surface of - which forms a part of the conical surface, and the outline of the groove 15g is the same as that of the groove 15g which forms a part of the conical surface. 〇A convex groove 16LIs with a contour is set up, and a small boot stock 144 (D convex groove 16&) of Rin is fitted into a concave groove of the - small block 14m, and a small plotter 14 & the following small blocks 14@, 144.
---, each plotter 14., 1 is arranged along each groove.
By driving 41-- in the same manner as in the above embodiment, 11 can be made into large and small boot starter groups. Concave groove 15・-
-1 and the convex strips 11116@-...-, there is a risk that the small blocks 15., i31--1ns may pass between the iris and the sliding surface of each small block 15, i31--1ns. In addition, as another modification, blocks 10g and 101 located at the top of the small boot block group 11. If the boots located above and below 0 are small block groups, the setting irradiation IIFOjI# shape can be further set arbitrarily.

The present invention has been described in detail above.According to 0**, each plotter in the small plotter group constituting the diaphragm has a radiation field limited to 1iK, where no radiation is incident. This can prevent the formation of a penumbra in the body.In addition, with a radiation therapy device that has this diaphragm, it is possible to suppress the occurrence of radiation damage to healthy tissues. 0

[Brief explanation of drawings]

The first part or opening is a schematic explanatory diagram showing a conventional radiation irradiation limiting device (aperture), the second part is a diagram showing the radiation-irradiation IF obtained by the radiation field limiting device, Figure 4 (2) and (2) are conventional oat*
ytiv radiation field limiting device (aperture))
Figure 1, 5th meter shows the radiation-irradiation field obtained by the JILIIO radiation layer field determination device.
Figures and Figure 7 are schematic diagrams showing that a penumbra is produced in the irradiation field by the improved lid radiation stratification W@electronic device Ij111%
Figure jl18 shows an apparatus for determining the number of shots (aperture) which is an embodiment of this invention.
- one penumbra, 10 g. 10t block, 11.12-Small plotter details, t
5g, 13&, 13g ”-13s-small block,
14g, 14h. 14# - Small block, 15th - Concave groove, 16.
, No. 16 - Convex groove. Agent: Patent Attorney Noriyuki Chikara (1 member) Figure 3 Figure 4 Figure 7 Figure 5P18

Claims (1)

[Claims] A virtual cylinder having a central axis containing radiation 1IiIII,
A small block of the number of bonds having the same shape as cut by 2,000 different planes including the central axis and cut by two different types of conical planes having the radiation source as the apex and having a predetermined central angle of O with respect to the central axis. The two groups of small blocks formed by arranging the plurality of small blocks so that the same curved surfaces are in contact with each other are arranged so that the plane including the central axis formed by each group of small blocks is relative to each other. At least one set of the small bootstock group is placed under the radiation source, and each of the small bootstock in the small bootstock is movable along both outer circumferences of the virtual cylindrical body. A radiation field limiting device characterized in that the actual cage radiation field and the set radiation field are made to coincide with each other.