JPH0111266Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to a radiation therapy device that performs treatment by irradiating radiation to the affected area of a patient.

(B) Prior Art Conventionally, so-called cobaltography has been carried out in which a radiographic image is photographed on a film using a radiation source of a radiation therapy apparatus, such as cobalt-60.
However, since the main purpose of the radiation source in this case is radiotherapy, a large capacity of 1,500 to 4,000 cuys is required, so it is enclosed in a capsule with a diameter of about 10 to 15 mm, which means that the focal point during cobaltography imaging is large. There was a problem with the images taken being very blurry.

(c) Purpose The purpose of this invention is to provide an improved radiation therapy device that can perform cobaltography without image blur caused by a large focal point.

(d) Configuration The radiation therapy device according to this invention is equipped with a small-capacity radiation source for cobaltography, in addition to a large-capacity radiation source for treatment, and this small-capacity radiation source is used during cobaltography imaging. It is characterized by

(e) Example In FIG. 1, a radiation source container 1 is made of a radiation-shielding material (for example, lead).
A radiation source holder 2 is movably arranged inside.
This radiation source holder 2 holds a large-capacity radiation source 3 for treatment and a small-sized small-capacity radiation source 4 for cobaltography. In this embodiment, the holder 2 is linearly reciprocatable and advances the radiation sources 3, 4 from the illustrated storage position to the position of the radiation port 5;
It is driven by the motor 6 via the crank mechanism 7 so as to retreat from that position to the storage position. Near the storage position of the container 1, a tungsten alloy 8 or the like having a higher radiation shielding ability is arranged.

When the radiation source holder 2 moves forward and the radiation source 3 or 4 is positioned at the radiation port 5, the patient 10 on the bed top 11 is irradiated with radiation through the movable aperture 9, and the film 1 is
A cassette 13 containing a patient 10 is placed under the top plate 11, and a radiographic image of the patient 10 is taken on a film 12. In order to confirm the irradiation field, a mirror 14 is provided at the tip of the holder 2 so that the light from the lamp 15 can be reflected and irradiated toward the patient 10.

The radiation sources 3 and 4 are as shown in FIG. 2A and B,
It is housed in cylindrical capsules 31 and 41.
The lids 32 and 42 are sealed by welding, and the radiation sources 3 and 4 are sealed together by welding.
are sealed in the capsules 31, 41.
Radiation source 3 is for treatment and requires a large capacity of about 1500 to 4000 cuyuri, so capsule 3
For example, 10 to 15 mm in diameter and height when stored in 1
It is large in size, approximately 29mm. On the other hand, since the radiation source 4 is used for cobaltography, a small capacity of a few cuys is sufficient, and when housed in the capsule 41, it has a diameter of 1 mm and a height of 1 mm.
Cobalt 60 with a small size of about mm can be considered. In this case, the higher the specific radioactivity of cobalt-60, the higher the Kuuri number even with the same dimensions.

As shown in Fig. 3, the control panel includes a changeover switch 21 for switching between treatment (T) and cobaltography (CG), and a switch 22 for turning on the radiation source.
A radiation source OFF switch 23 and a timer 24 are provided. When the selector switch 21 is pressed to select the cobalt graph side, the relay 60 is energized in the control circuit shown in FIG. 4, and its contacts 61, 6
2 turns on. After setting the timer 24 to the desired imaging time, press the radiation source ON switch 22. Then, the relay 70 is energized and its contacts 71 are turned on.
The motor 6 turns on and the holder 2 moves forward. When the radiation source 4 reaches the radiation port 5, the limit switch 92 is operated and its contact is switched from the upper side to the lower side in FIG. 4. Therefore, the power supply to the relay 70 is stopped and the contact 71 is turned off, thereby stopping the motor 6 and stopping the radiation source 4 at the position of the radiation port 5. At this time, the timer 24 is energized by switching the contacts of the limit switch 92, and the timer operation is started. When the time is up, the contact of the timer 24 is switched from the upper side to the lower side in FIG. 4, and the motor 6 is energized to the reverse direction. As a result, the holder 2 begins to move backward, and when it reaches the retracted position, the limit switch 93 is turned off, the motor 6 stops, and the holder 2 stops at the retracted position. Radiation is irradiated from the radiation source 4 only while the radiation source 4 is at the position of the radiation port 5, that is, for the time set by the timer 24, and a transmitted image is photographed on the film 12. When the radiation source OFF switch 23 is pressed before time-up, the motor 6 is immediately energized to the reverse side, the radiation source 4 is immediately retreated from the position of the radiation port 5, and radiation irradiation is immediately turned OFF.

When performing normal radiotherapy, the changeover switch 21 is selected to the treatment side, and the timer 24 is set to the desired treatment time. Then, the relay 50 is energized, its contacts 51 and 52 are turned on, and the relay 60 is turned on.
Since the energization to is stopped, the contacts 61 and 62 are
It turns off. Next, when the switch 22 is pressed, the relay 80 is energized, its contact 81 is turned on, the motor 6 rotates forward, and the holder 2 moves forward. When the radiation source 3 reaches the position of the radiation port 5, the limit switch 91 is activated.
is switched, the relay 80 is de-energized, the motor 6 is stopped, and at the same time, the timer 24 starts operating, and the treatment by irradiating the affected area of the patient 10 with radiation is started. Thereafter, the same operations as in the case of cobalt graphing described above are performed.

In the case of cobalt photography, the amount of blur ΔV of the image captured on the film 12 is proportional to the size of the focal point as shown by the following equation.

ΔV=(M・N)・S However, M: Distance between the subject and the film N: Distance between the focal point and the subject S: Size of the focal point Therefore, as mentioned above, when using a radiation source 4 with a small capacity and small dimensions, By using this, it is possible to reduce blurring and obtain an image with high sharpness and excellent contrast.

In addition, in the above, the radiation sources 3 and 4 were moved forward and backward by linearly reciprocating the holder 2, but as shown in FIG. Mechanically, various configurations can be made, such as a configuration in which a certain radiation source 3, 4 is advanced to the position of the radiation port 5 and returned from that position to its original storage position.

(F) Effects The radiation therapy device of this invention is equipped with a small radiation source with small capacity and dimensions separately from the therapeutic radiation source, and cobaltography is performed using this small radiation source, so the focal point is small. As a result, it is possible to photograph a transmitted image with less blur, high sharpness, and excellent contrast. Furthermore, the cobaltography radiation source is placed at the same position as the radiation source during treatment, and photographs can be taken under the same geometric conditions with the same magnification as during treatment, making it easy to distinguish between before and after treatment. It is possible. Furthermore, it has a simple structure, does not require special protective equipment or mechanisms, and is therefore inexpensive.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of the overall structure of an embodiment of this invention, Fig. 2 A and B are schematic sectional views of the radiation source capsule, Fig. 3 is a front view of the control panel, and Fig. 4 is a control circuit diagram. , FIG. 5 is a schematic sectional view of a modified example. 1...Radiation source container, 2...Radiation source holder, 3...Therapeutic radiation source, 4...Radiation source for imaging, 5...Radiation port, 6
...Motor, 7...Crank mechanism, 10...Patient, 11...Bed top plate, 12...Film, 2
4...Timer, 31, 41...Capsule.

Claims (1)

[Scope of utility model registration request] A radiation shielding radiation source container, a radiation source holder that is movable within the radiation source container, and a radiation source that is held by the radiation source holder and that travels from a storage position in the radiation source container to a radiation port and is stored from the radiation port. A radiotherapy apparatus having a large-capacity radiation source for treatment that returns to a position, a small-capacity radiation source with a small size for radiographic imaging that is separate from the treatment radiation source and held in the radiation source holder; and a control device that controls one of the large-capacity radiation source and the small-capacity radiation source to advance from the storage position to the radiation port and return from the radiation port to the storage position in response to switching between treatment and imaging. A radiation therapy device featuring: