JPH05237198A - Multisplitting wedge filter of radiation treating device - Google Patents

Abstract

PURPOSE:To enable the impartation of the radiation dose of the wedge isodose distribution optimum for lesion in the case of irradiation of the lesion in the irregular irradiation field formed by multisplitting collimators by utilizing the conventional integrated wedge filter. CONSTITUTION:The number of divisions of the multisplitting wedge filters 7 is the same as the number of divisions of the multisplitting collimators 5 and the width 10 thereof is aligned on the irradiation field 11. Position marks 16 are attached to respective central axes 15 and these axes are slid and moved. The sliding plane thereof is formed as a linear conical parallel plane. Such multisplitting wedge filters 7 are installed in the upper part or lower part of the multisplitting collimator 5. As a result, the multisplitting wedge filters are respectively so slid and moved as to be aligned to the irregular irradiation fields formed by the multisplitting collimators, by which the radiation dose of the wedge isodose distribution 14 optimum to the lesion is applied to the lesion 8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a radiation treatment apparatus,
Especially, it relates to the wedge filter which is the accessory.

[0002]

2. Description of the Related Art Conventionally, a wedge filter of this type of radiotherapy apparatus is integrated regardless of the type of a diaphragm device for a radiation irradiation field, and the wedge isodose angle is generally 15 degrees.
Four types, °, 30 °, 45 ° and 60 °, were specified as standard products. A general radiation irradiation field diaphragm device is composed of four pairs of block bodies each made of, for example, a heavy metal, which are arranged in two rows in a grid pattern, and these four block bodies form various rectangular irradiation fields. Was.

In general, a wedge filter is used when it is desired to give a wedge isodose distribution of a prescribed angle to a lesion by external irradiation, and a wedge filter or an upper part of a diaphragm mechanism section capable of forming various rectangular irradiation fields. It was installed at the bottom.

However, recently, as a special type of diaphragm device, the number of radiotherapy devices in which a multi-division collimator is introduced in the lower stage of the diaphragm mechanism section arranged in two stages is increasing, and this multi-division collimator is used. The number of radiotherapy methods for irregularly shaped irradiation fields that are closer to the shape of the lesion has also gradually increased. Furthermore, even in the external irradiation of this irregular irradiation field, if it is desired to give a tilted wedge isodose distribution again in the lesion, radiotherapy is performed using the conventional integrated wedge filter. ..

[0005]

Utilizing the above-mentioned conventional wedge filter having an equal dose distribution of wedges having a certain defined angle, the diaphragm device of the radiation irradiating section is stepwise at each leaf of the multi-division collimator. When externally irradiating a lesion having a formed irregular irradiation field, the irregular shape is formed stepwise by the central axis of the wedge contour distribution of the integrated wedge filter and each leaf of the multi-division collimator. Since the variable center positions of the rectangular irradiation fields formed by the leaves facing each other in the irradiation field do not match, there is a drawback that the optimal dose of wedge isodose distribution cannot be given to the entire lesion.

[0006]

The multi-segment wedge filter of the radiotherapy apparatus of the present invention has the same number of wedge filters as the number of logarithms of the multi-segment collimator of the radiation irradiation section,
The leaf width of the multi-division collimator and the division width of each wedge filter were matched on the irradiation field. In addition, a position mark is attached to the center axis of the wedge equal dose distribution of each wedge filter of the multi-divided wedge filter so that it can slide, and the slide surface between adjacent wedge filters is parallel to the radiation source in the pyramid. Formed and configured.

In the radiotherapy apparatus of the present invention, the multi-segment wedge filter as described above is installed above or below the diaphragm mechanism unit having the multi-segment collimator of the radiation irradiating section so that each leaf of the multi-segment collimator has a staircase. It is configured by matching the central axes of the wedge isodose distributions of the wedge filters with the variable center positions of the rectangular irradiation fields formed by the leaves facing each other in the irregularly shaped irradiation field formed above.

[0008]

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

FIG. 1A is a longitudinal section of a diaphragm mechanism section having a multi-segment collimator in the radiation irradiating section of the radiation treatment apparatus of one embodiment of the present invention and a multi-segment wedge filter installed at the lower end of the radiation irradiating section. It is a side view, and the division drawing (B) of FIG.
Shows a wedge isodose distribution of a wedge angle θ near a lesion formed by a pair of opposed leaves of a multi-divided collimator and a wedge filter of a multi-divided wedge filter. It is a longitudinal cross-sectional view rotated in a direction.

FIG. 2 is a plan view showing a state where the central axes of the wedge isodose distributions of the wedge filters of the multi-division wedge filter are aligned on a straight line, which is the same state as a conventional integrated wedge filter. Yes, FIG. 3 is a side view of FIG. FIG. 4 is a plan view showing a state where the central axis of the wedge isodose distribution of each multi-division wedge filter of FIG. 2 is slid and moved, and FIG. 5 is a side view of FIG.

FIG. 6 shows the upper diaphragm mechanism in the radiation irradiation unit of FIG. 3, the irregular irradiation field formed on the stairs of each leaf of the multi-division collimator, and the respective leaves of the multi-division collimator facing each other. FIG. 2 is a plan view showing a variable center position of the formed rectangular irradiation field as viewed from the radiation source side of the distribution (A) of FIG. 1.

In the diagram (A) of FIG. 1, the radiation flux 3 radiated from the radiation source 2 of the radiation irradiating section passes through the diaphragm mechanism section 4 in the upper stage and the multi-division collimator 5 of the pyramid parallel type in the lower stage.
Irradiation is performed on the pyramidal parallel type multi-division wedge filter 7 installed on the lower base plate 6 of the radiation irradiation unit 1. Also,
The leaf width 9 of the multi-segment collimator 5 and the wedge filter width 10 of the multi-segment wedge filter 7 are the irradiation field 11
Match above.

As shown in the diagram (B) of FIG. 1, the radiant flux 3 that has passed through the multi-division wedge filter 7 is placed on the body surface of the patient 12, and a pair of opposing leaves 5a, 5b of the multi-division collimator 5 are provided. 1 passes through the rectangular irradiation field 13 formed by
A wedge isodose distribution 14 having a wedge angle θ is formed in a lesion 8 within 2. Further, a position mark 16 indicating the central axis 15 of the wedge isodose distribution 14 of the wedge filter 7a, which is one piece of the multi-division wedge filter 7 shown in FIG.
By sliding and moving, the rectangular irradiation formed by the pair of opposed leaves 5a and 5b in the irregular irradiation field 17 formed on the stairs at each leaf of the multi-division collimator 5 shown in FIG. The variable center position 18 of the field 13 can be easily matched. The variable center position 18 is the center of a rectangular irradiation field formed by a pair of opposed leaves of the multi-division collimator 5, and the number of rectangular irradiation fields is the same as the number of pairs of the multi-division collimator 5.

Therefore, it can be seen that a stepwise irregular irradiation field 17 is formed depending on the size of the rectangular irradiation field. The shape of the lesion 8 is generally said to be irregular. Irregular irradiation field 1 formed by multi-segment collimator 5
When a conventional integrated wedge filter 19 as shown in FIG. 2 is used at the lower end of 7, the lesion 8 of the patient 12
Since each variable center position 18 of the irregular irradiation field 17 in is not in a straight line, the wedge isodose distribution 14 aligned in a straight line with the integrated wedge filter 19 does not match,
It can be seen that the wedge isodose distribution 14 in the entire lesion 8 is non-uniform.

The mounting structure of the multi-divided wedge filter 7 installed on the base plate 6 shown in FIGS. 1 to 5 is easily conceivable, and therefore its description is omitted. Therefore, the sliding mechanism of the multi-divided wedge filter 7 and the structure for preventing the multi-divided wedge filter 7 shown in FIG. Although the method for the position mark 16 of the central axis 15 of the wedge equal dose distribution 14 of each wedge filter of the multi-divided wedge filter 7 is also omitted, generally, it is filled in with thin lines or marking lines on the surface of the wedge filter. The method is also good. Further, depending on the mounting structure of the multi-divided wedge filter 7, a method of measuring the slide movement amount of the multi-divided wedge filter 7 by substituting it at another position without writing on the surface of the wedge filter may be used.

As described above, the multi-division collimator 5
By slidably moving the pyramidal parallel type multi-division wedge filter 7 matching the irregular irradiation field 17 formed by the above, it is possible to give the optimum dose of the wedge isodose distribution 14 to the entire lesion 8 of the patient 12. it can.

[0017]

As described above, the present invention has the same number of wedge filters as the number of pairs of multi-division collimators in the radiation irradiating section, and determines the width of each leaf of the multi-division collimator and the division width of each wedge filter. To match
Also, multi-divided wedge filters are attached to the center axis of the wedge isodose distribution of each wedge filter, and a slide mark is made to slide, and the slide surface between adjacent wedge filters is formed parallel to the radiation source in the pyramid. Optimal wedge isodose distribution even in irregular lesions by installing a multi-division wedge filter on the upper part (source side) or lower part (irradiation field side) of the diaphragm mechanism that has the multi-division collimator of the radiation irradiation part. Has the effect of being able to give.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a radiation irradiation unit and a multi-divided wedge filter according to an embodiment of the present invention (division A), and a side view showing a wedge isodose distribution near a lesion of the wedge filter (division B).

FIG. 2 is a plan view of a multi-divided wedge filter.

FIG. 3 is a side view of a multi-divided wedge filter.

FIG. 4 is a plan view of a multi-divided wedge filter.

FIG. 5 is a side view of a multi-divided wedge filter.

FIG. 6 is a side view showing an irregular irradiation field formed by an upper diaphragm mechanism and a multi-division collimator.

[Explanation of symbols]

 1 Radiation irradiation part 2 Radiation source 3 Radiation flux 4, 4a, 4b Upper diaphragm mechanism part 5 Multi-division collimator 5a, 5b Leaf 6 Base plate 7 Multi-division wedge filter 7a Each wedge filter 8 Lesion 9 Leaf width 10 Wedge filter width 11 Irradiation field 12 Patient 13 Rectangular irradiation field 14 Wedge isodose distribution 15 Central axis 16 Position mark 17 Irregular irradiation field 18 Variable center position 19 Integrated wedge filter

Claims (4)

[Claims] 1. A radiation therapy apparatus comprising a multi-segment collimator having a plurality of leaves and a wedge filter having the same number as the number of pairs of the multi-segment collimator, wherein each leaf width of the multi-segment collimator and each of the wedge filters. A multi-divided wedge filter characterized in that the division width is matched on the irradiation field. 2. The multi-divided wedge filter according to claim 1, wherein the wedge-dose distribution of each wedge filter of the multi-divided wedge filter is marked with a position mark on the central axis and slidably moved. 3. A multi-divided wedge filter, wherein slide surfaces between adjacent wedge filters of the multi-divided wedge filter are formed parallel to a line source in a pyramid shape. 4. The multi-division wedge filter according to any one of claims 1, 2 and 3, above (a radiation source side) or below (a radiation side) a diaphragm mechanism having each collimator of a radiation irradiation section.
A radiotherapy device characterized by being installed in a.