JPH0547796B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a whole body counter that determines the presence or absence of a trace amount of radioactive material taken into the body from outside the body using a radiation detector. Regarding.

(Prior Art) FIG. 3 shows a schematic configuration diagram of a conventional whole body counter. In the figure, whole body counter 1
0 is mainly composed of a radiation detector 4, a shielding device (shielding body) 3, a transporting device (transporting bed) 2, and a signal processing device 6. 1 is the subject. The whole body counter 10 is configured to detect an extremely small amount of radioactive material in the body of the subject 1.
A radiation detector 4 is detected by a shield 3 made of iron, lead, etc.
to improve the S/N ratio. That is, since the radiation detector 4 generates a signal (background count) due to external radiation from the subject 1 itself or the surroundings even in the absence of radioactive substances, the shield 3 prevents this background count from occurring. It is designed to be small.

In addition, when determining whether or not radioactive material has been taken into the body, the statistical dispersion of the background count of the radiation detector 4 is taken into account, and the count value that exceeds this statistical dispersion (usually background count ±3σ) is determined. A method was adopted in which the presence or absence of the information was determined when the information was obtained.

(Problem to be solved by the invention) However, although the subject 1 himself releases natural radioactivity such as ⁴⁰ K, which is associated with an increase in the background count, the contribution to this increase is not at all due to the background count. It was not taken into account in the ground count.
That is, in the conventional method, it was not clear to distinguish between natural radioactivity from the subject 1 himself and radioactive substances actually taken in. For this reason, there was a problem in that the accuracy of determining whether or not radiation was taken into the body decreased.

(Means for Solving the Problems) In order to achieve such an object, the present invention has the following features:
A weight scale is provided to measure the weight of the subject, which is proportional to the amount of natural radioactivity held and released as a body component of the subject, and this weight is input to a signal processing device to correct the background count. It is characterized by

(Function) Focusing on the fact that the amount of natural radioactivity ^40K , etc. that a test subject possesses as a body component is proportional to the test subject's weight, we developed a conventional whole body counter component. was equipped with a scale to detect the subject's weight. Based on the measured value, the subject's own natural radioactivity ^40K is calculated using a signal processing device, and the background count is corrected.
Accurately determine whether radioactivity has been taken into the body.

(Example) Next, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows a schematic configuration diagram of an embodiment of the present invention, in which A is a front view thereof and B is a plan view thereof. In the figure, the parts having the same functions as in Figure 3 are as follows:
The same reference numerals are given. The whole body counter 20 mainly includes a radiation detector 4, a shield 3,
It is composed of a transport bed 2, a signal processing device 6, and a weight scale 5 provided on the transport bed 2. The subject 1 lies supine on the weight scale 5 on the transport bed 2, is positioned directly below the radiation detector 4 surrounded by the shield 3, and is measured for a certain period of time. At this time, the measured value of the subject 1 is input to the signal processing device 6 connected to the radiation detector 4, which calculates the subject 1's own natural radioactivity of ⁴⁰ K, etc. This method corrects the amount of radioactivity and accurately determines whether or not radioactivity has been taken into the body.

Next, FIG. 2 shows a schematic diagram of another embodiment of the present invention, in which A is a front view thereof and B is a plan view thereof. In the figure, the whole body counter 30 mainly includes a radiation detector 4, a shield 3, a transport bed 2, a signal processing device 6, and a weight scale 5 provided on an operating post section 7. The subject 1 enters the operation post section 7 in order to enter various conditions for starting measurement, such as name, affiliation, measurement category, etc., and while performing the operation, a message appears on the floor of the post section 7. The weight of the subject 1 is measured by the provided weight scale 5A, and this weight value is input to the signal processing unit 6 and stored.

After this input operation of the post section 7, the subject 1:
The patient lies supine on the transport bed 2, is transported directly under the radiation detector 4 surrounded by the shield 3, and is measured for a certain period of time. Therefore, the content of natural radioactivity ⁴⁰ K, etc. of each subject can be calculated from the weighed value obtained by the weight scale 5A, and the measurement and determination of whether or not radioactive substances have been taken into the body becomes accurate.

(Effects of the Invention) As explained above, according to the present invention, there is provided a weighing scale for measuring the weight of the subject, which is proportional to the amount of natural radioactivity retained and released as a body component of the subject. and this measured value is input to a signal processing device to correct the background count.
The problems of the conventional technology have been effectively solved, the presence or absence of radioactive substances can be determined accurately, and the radiation exposure inside the body of the examinee can be controlled down to ^{a trace} level. This has the effect of improving the reliability of natural radioactivity without misjudging it as an actual radioactive substance taken into the body.

[Brief explanation of the drawing]

FIG. 1 shows a schematic configuration diagram of an embodiment of the present invention, in which figure A is a front view thereof, figure B is a plan view thereof,
FIG. 2 shows a schematic configuration diagram of another embodiment of the present invention, in which figure A is a front view thereof, figure B is a plan view thereof,
FIG. 3 is a schematic diagram of a conventional whole body counter. 2: Transport bed, 3: Shielding body, 4: Radiation detector, 5, 5A: Weight scale, 6: Signal processing device,
7: Operation post, 20, 30: Whole body counter.

Claims (1)

[Claims] 1. A radiation detector that detects radioactive substances that have contaminated the body of a subject; a shielding device that is provided surrounding the radiation detector to shield radiation from the outside and reduce background counts caused by the radiation;
A whole body counter that includes a transport device that transports the patient directly below the radiation detector, and a signal processing device that processes the detection signal from the radiation detector in consideration of the background count. A weight scale is provided for measuring the weight of the subject, which is proportional to the amount of natural radioactivity held and released as a body component of the subject, and this weight value is input to the signal processing device to correct the background count. A whole body counter characterized by: