JPS625630B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation therapy apparatus that can simultaneously obtain the dose distribution of radiation irradiated to a patient during radiation therapy.

Conventionally, radiation therapy devices include, for example, linear particle accelerators that accelerate electrons using high-frequency electric fields;
A betatron that accelerates electrons using an alternating magnetic field, a cobalt treatment device that uses a radioisotope such as cobalt-60 as a radiation source, and the like are known.

When performing treatment using the radiation therapy device, first, the specifications such as the shape and location of the lesion are determined using various diagnostic devices such as an X-ray CT device, and then,
The dose of radiation to be irradiated is calculated using a treatment planning device, etc., and the necessary data is obtained. Based on the obtained data, the affected area is treated by irradiating radiation using a radiotherapy device.

Next, regarding the outline of the radiotherapy device, the first
The explanation will be given with reference to the figures and FIG.

As shown in FIG. 1, a fixing frame 1 for fixing the radiation therapy device is installed in the treatment room.
A rotary pedestal 2 is attached to the fixed pedestal 1 so as to be rotatable about a center line A. An irradiation head 3 is attached to the horizontal axis of the rotating pedestal 2, and a treatment bed 5 for holding a patient 4 in a fixed position is installed in front of the irradiation surface of the irradiation head 3. Furthermore, the cassette 7 containing the X-ray film is attached to the rotating mount 2 via the support 8, and the photosensitive surface of the X-ray film stored in the cassette 7 is always in the irradiation head regardless of the rotation of the rotating mount 2. It is arranged so as to face the irradiation surface of No. 3.

On the other hand, irradiation of radiation such as X-rays from the irradiation surface of the irradiation head 3 is carried out as follows. That is, as shown in FIG. 2, electrons generated in the electron generating section 9 are guided to the electron accelerating section 10, and microwaves oscillated by the microwave generating section 11 are applied to the electron accelerating section 10 to generate a microwave electric field. This generation accelerates the electrons guided to the electron acceleration section. The accelerated electrons are then deflected in a desired direction by the deflection unit 12, the deflected electron beam is converted into X-rays, and the diaphragm unit 13 installed in the irradiation head 3 is used to irradiate the affected area 6 according to the target direction. form a field,
The affected area 6 is irradiated with X-rays through the aperture part 13. The X-rays that have passed through the body of the patient 4 are also irradiated onto the film stored in the cassette 7. Then, an electron generation section 9, an electron acceleration section 10, a microwave generation section 1
1. A rotating mount 2 equipped with a deflection section 12, a constriction section 13, and a cassette 7 is placed around a center line A.
It is rotatably driven so that the affected area 6 can be treated by irradiating X-rays from all angles perpendicular to the center line A.

Furthermore, prevention of X-ray exposure to normal tissue and analysis of irradiation dose are performed as follows. That is,
As shown in FIG. 2, the angle detection section 15 detects the rotation angle of the rotating frame 2 driven by the rotation mechanism section 14, and outputs the detected signal to the aperture control section 16. The aperture control unit 16 controls the aperture unit 13 according to the rotation angle of the rotary pedestal 2 from the detection signal and data regarding the affected area 6 obtained in advance,
X-rays are irradiated only to the affected area 6 to minimize the exposure dose to normal tissues. Also, patient 4
When the film in the cassette 7 is irradiated with X-rays passing through the patient's body, the film is exposed to light so that the degree of blackening is proportional to the irradiation dose on the tomographic plane of the affected area 6. By analyzing the degree of blackening of this film, it is possible to know the approximate value of the irradiation dose distribution in the affected area 6 and its surroundings.

However, as mentioned above, what is obtained by analyzing the degree of darkening of the film after irradiation with radiation is a relative dose, moreover, it is an approximate value, and the exact absolute dose irradiated to the affected area is unknown. Therefore,
There is a problem that accurate and optimal radiation therapy cannot be performed.

This invention was made in view of the above-mentioned circumstances, and it measures the amount of radiation that has passed through the patient's body by arranging a dosimeter so as to sandwich the treatment table holding the patient and facing the irradiation head. The purpose is to provide a radiation therapy device that enables accurate and optimal radiation therapy by making it possible to determine the irradiation dose distribution during irradiation and the integrated dose value after irradiation using absolute dose values. be.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a schematic explanatory diagram showing one embodiment of the present invention, FIG. 4 is an explanatory diagram showing the relationship between the aperture part and the dosimeter, and FIG. 6 is a block diagram showing the embodiment.

The mechanical configuration of the radiation therapy device according to the present invention differs from the conventional radiation therapy device shown in FIG. 1 in that a dosimeter 17 is provided in place of the cassette 7, as shown in FIG. It is. That is, the dosimeter 17 is attached to the rotating pedestal 2 via the support 8, and the dosimeter 17 is attached to the top plate of the treatment bed 5 that holds the patient 4 regardless of the rotation of the rotating pedestal 2. Surface and irradiation head 3
The irradiation surface of the irradiation surface is always opposed to the irradiation surface. As shown in FIG. 4, on the entrance surface of the dosimeter 17, a large number of semiconductor detection elements 20 are arranged in a matrix to detect radiation and convert it into a voltage proportional to the radiation dose. On the other hand, dosimeter 1
A diaphragm (not shown) is incorporated in the irradiation head 3 facing away from the irradiation head 7 . As shown in FIG. 4, the diaphragm unit includes a first diaphragm device 19 that moves in the direction B in FIG. It has a second diaphragm device (not shown) that moves in a direction perpendicular to the direction and includes a plurality of sets of diaphragm blades arranged opposite to each other. The diaphragm section is configured to form an opening corresponding to the shape of the affected area 6 by moving opposing diaphragm blades of the first diaphragm device 19 and a second diaphragm device (not shown) toward and away from each other. Moreover, if a large number of semiconductor detection elements 20 are arranged in a matrix on the entrance surface of the dosimeter 17, as shown in FIG. 4, so as to correspond to the aperture blades 19a to 19g, When radiation is irradiated from the irradiation head 3 through the diaphragm, the semiconductor detection elements 20b ₆ to 20b ₈ , 20c ₅ to 20c ₉ , 20 are located in a region similar to the shape of the aperture of the diaphragm.
A voltage signal proportional to the radiation dose is output from d ₄ to 20d ₁₀ , _{20e 4 to} 20e 9 , and 20f ₆ to 20f ₈ .

The circuit configuration of the radiation therapy device according to the present invention differs from that of conventional radiation therapy devices as follows:
As shown in FIG. 5, the dose detection section 21, the converter 2
2. A data collection section 23, a storage section 24, and a reconstruction section 25 are newly provided.

The dose detection unit 21 includes a semiconductor detection element 20 and an amplifier, and is configured such that the semiconductor detection element 20 irradiated with radiation outputs a voltage signal proportional to the radiation dose for each element. The converter 22 inputs the output signal from the dose detection section 21, converts it into a digital signal of a code, for example, a BCD code, and outputs the digital signal. Data collection section 2
3 inputs the angle detection signal output from the angle detection unit 15 that detects the rotation angle of the rotation gantry 2 and the digital signal output from the converter 22, and collects radiation data at the rotation angle of the rotation gantry 2. . The storage unit 24 stores various radiation data collected by the data collection unit 23. Furthermore, the reconstruction unit 25 calculates the irradiation dose distribution and absolute dose value based on the collected radiation data and the like, and outputs the results to a display/recording device (not shown).
Note that the aperture control section 16 controls the aperture opening degree of the aperture section 13, that is, the irradiation field, based on the angle detection signal output from the angle detection section 15 and preset aperture control data. There is.

Since the radiation therapy apparatus is configured as described above, when radiation is irradiated from the irradiation head 3 to the affected area 6 while rotating the rotary pedestal 2 around the center line A, all information on the rotary pedestal 2 is stored in the storage section 24. Regarding the angle, the dose data of the radiation that passed through the body of the patient 4 will be collected and stored, and when reconstructed by the reconstruction unit 25 based on all the dose data obtained by rotating the rotating platform 2 once, the affected area will be The dose distribution of the radiation irradiated to 6 and its surroundings can be determined in absolute values. Furthermore, by storing the radiation dose distribution planned before treatment in the storage unit 24, it is possible to compare the dose distribution planned before treatment with the actual dose distribution after treatment. Furthermore, if the data of the radiation energy irradiated from the irradiation head 3 is stored in the storage unit 24, the reconstruction unit 2
5, radiation absorption data in each tissue of the patient 4 can be obtained. If the relationship between the blank radiation dose that does not pass through the patient 4 and the voltage that is converted by the semiconductor detection element 20 is stored in advance in the storage unit 24, the absolute dose value of the radiation that passes through the patient 4 can be determined. I can do it.

One embodiment of the present invention has been described in detail above,
This invention is not limited to the embodiments described above, and can be implemented with various modifications within the scope of the gist of the invention.

For example, the number of semiconductor detection elements and their arrangement method can be arbitrarily changed as necessary.
In addition, the aperture section may omit the second aperture device and the first aperture device may be omitted.
It may be equipped with only the diaphragm device.

According to this invention, the following effects can be achieved. In other words, in the radiation therapy apparatus according to the present invention, the dosimeter is provided so as to sandwich the treatment bed holding the patient and face the irradiation head, so that the amount of transmitted radiation at the angle at which the rotating pedestal is rotated can be measured. Can be accurately measured in absolute value. Furthermore, by performing reconstruction processing based on all the data obtained after one rotation of the rotating mount, the actual irradiation dose distribution in the affected area can be determined, and the dose distribution at the time of treatment planning and the actual irradiation dose distribution can be compared. can do. Therefore, with the radiation therapy apparatus according to the present invention, more accurate, safer, and highly accurate radiation therapy can be performed.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing a conventional radiotherapy device, Fig. 2 is a block diagram showing the same device, Fig. 3 is a schematic explanatory diagram showing an embodiment of the present invention, and Fig. 4 is an aperture section and dose amount. Explanatory diagram showing the relationship with the meter and the fifth
The figure is a block diagram showing the embodiment. 2... Rotating stand, 3... Irradiation head, 17...
Dosimeter, 23...data collection section, 24...storage section, 25...reconstruction section.

Claims (1)

[Claims] 1. In a radiation therapy device that treats an affected area by irradiating radiation from the irradiation head while rotating a rotary pedestal to which the irradiation head is attached,
A dosimeter that has a large number of detection elements that converts the radiation dose into signal data proportional to the dose, a data collection unit that collects the detection data output from this dosimeter for each rotation angle of the rotating mount, and the collected data. What is claimed is: 1. A radiation therapy apparatus comprising: a storage section that stores the data for each angle; and a reconstruction section that calculates the radiation dose distribution in the affected area based on the data for each angle stored in the storage section.