JP2007040945A - Device for calibration device for measuring dose such as radiation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a calibration device capable of optionally and quickly performing works, without having to exchange calibration radiation source by reducing the distance between the calibration radiation source and a device for measuring dose to be calibrated, in the device for calibrating the device for measuring dose, such as radiation. <P>SOLUTION: In place of a system performing attenuation of radiation from the calibration radiation source by the atmosphere, one among a plurality of mobile filters having different thicknesses or a materials, formed of radiation shielding metals, is used selectively for a single calibration radiation source. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a calibration apparatus for a dose measuring apparatus for radiation such as gamma rays.

  Conventional calibration equipment is equipped with multiple calibration radiation sources, and depending on the required dose rate, the intensity of the radiation source, the distance between the radiation measurement device placed on the carriage and the radiation source requiring calibration, and further integration Regarding the dosimetry device of the type, the dosimetry device was calibrated by changing the irradiation time.

  Therefore, in the actual calibration work, the radiation source is exchanged according to the type of dose measuring device to be calibrated, and the distance between the calibration carriage on which the dose measuring device is placed and the calibration radiation source is adjusted. By doing so, it was compatible with various dosimetry devices.

Such past techniques are described in detail in the following documents.
Japanese Patent Laid-Open No. 62-182687

  Changing the intensity of the calibration source and adjusting the distance between the calibration source and the calibrated dosimetry device have been recognized as necessary procedures in the past. In view of the current situation occupied by the present inventors, the present inventors have reached the conclusion that this is the biggest problem that requires a reduction in the working time of this part.

  In the conventional system, radiation is irradiated from the calibration radiation source to the outside of the irradiation shielding container through the collimator, and calibration is performed by using the attenuation of the radiation in the air calculated in advance. Therefore, the distance adjustment between the calibration radiation source and the calibrated dosimetry device for obtaining an appropriate numerical value has an important meaning, and it has been considered that it takes time for the adjustment.

  By creating several types of moving filters using radiation shielding metal that can calculate the radiation attenuation rate in advance and replacing the moving filter for a single calibration source, A result equivalent to the conventional type in which the distance of the calibration dosimeter is changed is obtained. In that case, it is desirable to use a plurality of moving filters having a thickness that is a multiple of the half value layer or 1/10 value layer of the radiation shielding metal used.

  An opening closing body made of the same radiation shielding metal as the moving filter or a separate substance is installed as a filter base in the external opening of the collimator of the irradiation shielding container in which the calibration radiation source used in the past is housed. A desired moving filter is matched with the filter substrate from among the moving filters, and a dose irradiated from the calibration source is selected.

  The structure required for such an apparatus is that a plurality of moving filters can be arbitrarily moved to a position facing the filter base, and the amount of radiation attenuation is stabilized by bringing the facing moving filters into close contact with the filter base. is there. Therefore, concentrically with the irradiation shielding container containing the calibration radiation source, the moving filter can move around it, and the moving filter facing the filter substrate is in close contact with the irradiation axis of the calibration source. Means to move are required.

  According to the present invention, since there is no need to use a cart on which a calibration dosimeter that has been used in the past is mounted, the travel time of the cart required for the calibration work becomes unnecessary, and in the air Since the radiation attenuation from the calibration radiation source is not used, the conventionally required space for air, that is, the distance between the calibration radiation source and the calibration dosimeter is not required. Furthermore, since the dose rate can be changed by the moving filter, it is not necessary to prepare a plurality of calibration radiation sources, and the great labor of exchanging the calibration radiation sources can be omitted. In addition, the outer surface of the structure constituted by the filter base and the moving filter has a curved surface that coincides with a part of a circle virtually drawn around the calibration radiation source as shown in FIG. The radiation dose can be made more uniform than the conventional collimator, thereby reducing the components that become scattered radiation.

  The structure of the embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 and 2, the collimator 10a is placed on the irradiation shielding container 10 in which the calibration source 8 and the collimator unit 10a corresponding thereto are accommodated. A guide rail 5 is installed in parallel with the axis. A seat plate 3 that can move on the guide rail 5 is placed. A ring 2 is placed on the seat plate 3, and the ring 2 places the calibration source 8 in FIG. It is attached so that the circular movement around the center is possible. A filter base 9 is fixed to the external opening of the collimator 10 a, and a plurality of moving filters 1 are installed on the ring 2. Reference numeral 4 denotes a driving device for circular movement of the ring 2, and 7 denotes a retracting device for linear movement of the seat plate 3.

  In the illustrated example, four types of moving filters 1, 1 a, 1 b, and 1 c are shown, all of which are supported by the ring 2. The surface of the structure constituted by the moving filter 1 and the filter base 9 has a curved surface that coincides with a part of a circle virtually drawn around the calibration source 8. When not in use, the filter base 9 and the moving filter 1 are separated from each other, and the moving filter 1 can move to any position as the ring 2 turns.

  When the moving filter 1 is selected and used now, the ring 2 is turned by the driving device 4 so that the moving filter 1 faces the filter base 9, and then the retracting device 7 and the seat plate 3 are moved. The entire ring 2 is moved along the guide rail 5 to bring the moving filter 1 into close contact with the filter base 9. With this operation, the calibration of the calibration dosimeter is installed at an appropriate position facing the collimator 10a by using the attenuation rate of the structure formed by the moving filter 1 and the filter base 9 calculated in advance. It becomes possible.

  If it is necessary to perform a configuration with another radiation dose, the retracting device 7 is moved backward to separate the moving filter 1 and the filter base 10a, and then the ring 2 is swung by the driving device 4, for example, a moving filter. If the la is faced to the filter base 9 and the moving filter 1a and the filter base 9 are brought into close contact with the pull-in device 7 again, the next calibration work can be performed.

  For these series of operations, various limit switches are used to assist the operation of the pull-in device 7 and the drive device 4, and the entire control and calibration operations are operated by a computer. However, the description is complicated in this application. I will omit it.

  According to the present invention, in the calibration work of radiation dosimetry apparatus widely used at present, the working space can be reduced, the working time can be shortened, the safety of workers can be ensured, the working cost can be reduced, etc. The path is expected to be diverse.

1 is a conceptual plan view of an embodiment of the present invention. It is a principal part cross-sectional view of FIG. It is an expanded sectional view of a filter base and a moving filter part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Moving filter 2 Ring 3 Seat plate 4 Drive apparatus 5 Guide rail 7 Pull-in apparatus 8 Calibration source 9 Filter base 10 Irradiation shielding container 10a Collimator

Claims (2)

  A plurality of moving filters made of radiation shielding materials each having a different thickness, a means for moving the moving filters to a position facing the collimator opening of the irradiation shielding container containing the calibration radiation source, and the above movement position. A device for calibrating a dose measuring apparatus for radiation or the like, characterized in that it comprises means for closely attaching the transferred filter to the opening of the collimator. 2. The calibration apparatus for a dose measuring apparatus for radiation or the like according to claim 1, wherein the surface of the moving filter has a curved surface that coincides with a part of a circle virtually drawn around the calibration radiation source. .

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