Individual radiation exposure dosimeter

The present invention relates to a dosimeter used for radiation measurement, and more particularly to a dosimeter used for personal exposure control of workers engaged in radiation work at a nuclear power plant, a research institution, etc., and environmental radiation measurement of a radiation control facility.

Thermal fluorescent dosimeters, film badges, and glass dosimeters are used as dosimeters used for personal exposure control of workers engaged in radiation work such as nuclear power plants and research institutes. In particular, since thermofluorescence dosimeters and OSL crystals can be used repeatedly, they are superior to film badges in terms of operating costs and are used by many users.

Personal exposure management using a thermofluorescence dosimeter will be described. Figure 5 shows a configuration example of an individual exposure dosimeter used for individual exposure management using a thermofluorescence dosimeter with four detectors.

The conventional personal exposure dosimeter 6 includes a detector 101 (three detectors are shown) that uses a thermal phosphor such as calcium sulfate as a radiation detection material, and an element plate 102 that holds the detector 101. It has a tubular structure and has a structure in which four parts of a holder 103 that inserts and holds the element plate 102 inside and a hanger 104 that is provided with a clip so that it can be easily attached to the clothes of an operator are integrated.

In this specification, the four parts of the detector 101, the element plate 102, the holder 103, and the hanger 104 are integrated as an individual exposure dosimeter 106, and the detector 101, the element plate 102, and the holder 103 are referred to as an individual exposure dosimeter 106. The dosimeter 116 is a combination of these three parts.

Next, the measurement method of the thermal fluorescence dosimeter will be described. As shown in Equation 1, the radiation amount is obtained by the product of the electric signal amount, the conversion constant, the sensitivity correction coefficient, and the device correction coefficient.

<maths num="1"><img file="JP2006266880A_D0001.tif" /></maths>

The electric signal amount expresses the light emitted when the detector receives the excitation energy as the electric signal amount, and is expressed by using the number of pulses, the integrated value of the current value, and the like.

The conversion constant is a constant for converting the amount of electric signal into the amount of radiation, and is determined by the component and amount of the detector.

The sensitivity correction coefficient is a correction coefficient for correcting variations in the detector, and is expressed as a ratio of the amount of light emitted by the reference detector to the amount of light emitted by the detector.

The device correction coefficient is a correction coefficient for correcting variations in the measuring device, and measures the light receiving unit that receives the light emitted when the detector receives the excitation energy and outputs an electric signal, and the electric signal output by the light receiving means. It is determined by the performance of the measuring unit that outputs the amount of electrical signal.

The device correction coefficient is expressed as a ratio of the radiation amount when the reference detector is measured by the reference measuring device and the radiation amount when the reference detector is measured by the measuring device.

Next, the code system in personal exposure management will be described. The personal exposure dosimeter 106 is provided on the hanger 104 with a user management barcode (not shown) printed with an ID number that uniquely identifies the user. Further, the dosimeter 116 includes a dosimeter management bar code 105 printed on the dosimeter identification code that uniquely identifies the dosimeter in the holder 103.

FIG. 6 is a diagram showing the definition of the dosimeter identification code of the dosimeter with four detectors.

The dosimeter identification code is composed of a dosimeter type code indicating the type of the dosimeter, a unique serial number, and a sensitivity rank code in which the sensitivity correction coefficient for each detector is coded. Furthermore, the dosimeter type code and the conversion constant have a one-to-one correspondence, and once the dosimeter identification code is determined, the conversion constant can be uniquely determined. The sensitivity rank code divides the sensitivity correction coefficient of the detector into, for example, five ranks (0.76 to 0.85, 0.86 to 0.95, 0.96 to 1.05, 1.06 to 1.15, 1.16 to 1.25), and each of them is 0, 1, 2, and 3. -Code by defining the code of 4. By this coding method, sensitivity correction is performed at a control level of 0.10 units within the limited amount of data of the dosimeter identification code.

The measuring device stores a correspondence table between the dosimeter type code and the conversion constant and a correspondence table between the sensitivity rank code and the sensitivity correction coefficient in the storage unit.

As a method of assigning an optical information recording carrier in personal exposure management, the user's name, dosimeter control number and body positioning mark are given to the dosimeter, and the dosimeter is attached to the position of the body indicated by the body positioning mark to manage personal exposure. The method for doing this is open to the public (for example, Patent Document 1).

Next, the OSL crystal will be described. OSL crystals were developed as next-generation radiation detection materials. OSL crystal components, laser irradiation methods, and light reception measurement methods have been published as measurement methods when OSL crystals are used as dosimeters (for example, Patent Documents 2 and 3).

Furthermore, the fiber for irradiation optical path and the fiber for light reception are bundled as one fiber, a dosimeter composed of OSL crystals is attached to the tip of the fiber, and the fiber for irradiation optical path is irradiated with laser light and emitted from the OSL crystal. A method of receiving and measuring OSL light with an optical light receiving fiber has been published (for example, Patent Document 4).<patcit num="1"><text>Special Table 2001-508875</text></patcit><patcit num="2"><text>Special Table 2000-503396</text></patcit><patcit num="3"><text>Special Table 2000-503759</text></patcit><patcit num="4"><text>Japanese Unexamined Patent Publication No. 11-237479</text></patcit>

<p> However, in a personal exposure dosimeter composed of one detector and an annular element plate, it is difficult to secure a surface on which the dosimeter identification code is printed, and it is necessary to print the control code on the element plate. It was necessary to secure a separate space, and it was difficult to achieve miniaturization.</p><p> The present invention is for solving the above-mentioned problems, and is provided with a dosimeter identification code on the element plate of an annular personal exposure dosimeter using OSL crystals or a thermal phosphor.</p>

<p> In order to achieve the above object, the personal exposure dosimeter of the present invention is composed of a detector that uses OSL crystals or a thermofluorescent substance as a radiation detection material, and an annular element plate that holds the detector, and is formed on the element plate. Provide a dosimeter identification code for managing the dosimeter.</p><p> The reading is performed by irradiating the dosimeter identification code with laser light and exchanging the absorbed energy for heat to recognize it as a character or a symbol.</p><p> With the above configuration, the personal exposure dosimeter can attach a dosimeter identification code for managing the dosimeter to the element plate.</p><p> The personal exposure dosimeter of the present invention is characterized in that information for operating and managing the dosimeter is provided on both sides of the element plate. For example, one side is a dosimeter identification code / conversion as information for managing the dosimeter. A constant / sensitivity correction coefficient is assigned, and an ID number that uniquely identifies the user as information for operating the dosimeter is assigned to the other back surface. In addition, in the case of environmental radiation measurement, a place ID number that uniquely identifies the place is assigned to the back side.</p><p> With the above configuration, the personal exposure dosimeter can directly record information for operating and managing the dosimeter on the element plate. In the conventional product, it is not possible to directly know the type of the element plate, and there is only a method of tracing from the information of the dosimeter identification code, but in the personal exposure dosimeter provided by the present invention, the information of the element plate is read. You can know it directly at.</p><p> In the personal exposure dosimeter of the present invention, the dosimeter identification code is directly printed on the radiation detection material by laser light or silk printing.</p><p> With the above configuration, the personal exposure dosimeter can give a larger amount of information, so that it is possible to give information such as the production lot number and the expiration date of the detector.</p><p> The personal exposure dosimeter of the present invention is characterized in that the dosimeter identification code is provided by a bar code, and is arranged radially on a surface parallel to the radiation detection material of the annular element plate holding the radiation detection material. The element plate control number is assigned by arranging the bar code.</p><p> With the above configuration, it is possible to add a large amount of information even in a space where characters cannot be printed.</p><p> In the personal exposure dosimeter of the present invention, the dosimeter identification code is provided by a bar code on one side of the element plate and alphanumeric characters on the opposite side.</p><p> With the above configuration, the personal exposure dosimeter can visually read the element plate control number even when the barcode cannot be recognized.</p><p> In the personal exposure dosimeter of the present invention, the dosimeter identification code is provided in the radiation detection material by the high-density optical information recording technique.</p><p> With the above configuration, the personal exposure dosimeter of the present invention can record a dosimeter identification code in a limited area of a radiation detection material by high-density optical information recording represented by a two-dimensional code. Further, the size of the element plate can be further reduced.</p>

<p> As described in detail above, according to the present invention, it is possible to provide an individual exposure dosimeter capable of assigning a dose meter identification code even to an individual exposure dosimeter having an annular element plate. It has a great effect.</p>

(Embodiment 1) An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of the personal exposure dosimeter of the present invention.

The personal exposure dosimeter 6 is composed of a detector 1 that uses OSL crystals or a thermofluorescent substance as a radiation detection material, an annular element plate 2 that holds the detector 1, and a holder 3 that holds the element plate 2.

The dosimeter identification code is recorded on the element plate 2 by the bar code 5. The dosimeter identification code is a dosimeter type code indicating the type of the dosimeter, a unique serial number (corresponding to the manufacturing lot number), a sensitivity correction coefficient of the detector 1, an ID number uniquely identifying the user, and the like.

The configuration of the dosimeter identification code can be freely changed depending on the purpose of measurement, and is not limited to the above configuration.

Further, as a recording method, in addition to a printing means such as a barcode, a non-contact readable medium such as an RFID chip and an antenna may be provided on the element plate 2 to store the dosimeter identification code.

(Embodiment 2) An example of an embodiment of an individual exposure dosimeter will be described.

FIG. 2 shows a dosimeter identification code printing example 1 of the personal exposure dosimeter of the present invention.

FIG. 3 shows a cross-sectional view of the dosimeter identification code printing example 1 of the personal exposure dosimeter of the present invention in AA'.

In FIGS. 2 and 3, a detector 1 that uses an OSL crystal or a thermofluorescent substance as a radiation detection material, an annular element plate 2 that holds the detector 1, and a holder 3 that holds the element plate 2 (with the first embodiment). (Not shown for the same reason), it is composed of a cover film 9 that covers the detector 1. For the cover film 9, for example, a pet resin is formed into a film and attached to the element plate 2 with an adhesive.

The dosimeter identification code is used by recording as a high-density optical information recording 7 such as a two-dimensional code by irradiating a detector 1 which is a radiation detection material with a laser beam, and attaching a cover film 9.

Further, after the cover film 9 covering the detector 1 is attached, the cover film 9 may be recorded as a high-density optical information recording 7 such as a two-dimensional code by irradiating the cover film 9 with a laser beam.

By recording with a high-density optical information recording 7 such as a two-dimensional code, it is possible to add a lot of information.

Further, by providing the information recording position on the upper surface of the detector 1, the width of the edge portion of the element plate 2 can be reduced, so that the size can be further reduced as compared with the first embodiment.

(Embodiment 3) An example of an embodiment of an individual exposure dosimeter will be described.

FIG. 4 shows a dosimeter identification code printing example 2 of the personal exposure dosimeter of the present invention.

The dosimeter identification code is characterized by having a barcode 5 on one side of the element plate 2 and an alphanumeric character 8 on the opposite side, so that a lot of information can be given.

The dosimeter identification code is assigned by arranging the bar codes arranged radially on the surface parallel to the detector 1 of the element plate 2, and the character information is printed on the opposite surface. As a result, even if the barcode 5 cannot be recognized, the character information as a part of the dosimeter identification code can be visually read.

Although the personal exposure dosimeter of the present invention is small, it can be provided with its operation management information, and even if the barcode, two-dimensional code, etc. cannot be read, the alphanumeric element plate control number is visually recognized. It is useful for dosimeters, etc.

<figref num="1">Configuration diagram of the personal exposure dosimeter of the present invention</figref><figref num="2">The figure which shows the same dosimeter identification code printing example 1.</figref><figref num="3">Cross-sectional view of the same dosimeter identification code printing example 1</figref><figref num="4">The figure which shows the same dosimeter identification code printing example 2</figref><figref num="5">Diagram showing a configuration example of a conventional personal exposure dosimeter</figref><figref num="6">Diagram showing the definition of the dosimeter identification code of four dosimeters with detectors</figref>

Code description

1 Detector 2 Element plate 3 Holder 4 Hanger 5 Barcode 6 Personal exposure dosimeter 7 High-density optical information recording 8 Alphanumeric characters 9 Cover film 16 Dosimeter