| 摘要 |
PROBLEM TO BE SOLVED: To reduce errors in counted values caused by K-X rays by estimating the dosage of K-X rays mixing into the first energy window after generated by photoelectric effect, which second gamma rays produce in a collimator and reducing it from the first measured value. SOLUTION: At signal outputting of camera heads 11 and 12, a location computing device 15 computes the incident location of gamma rays, and an energy computing device 17 computes an energy Z of the incident gamma rays. When an input signal Z is within the ranges of the energy windows of window circuits 19 and 21, the window circuits 19 and 21 each output one pulse, and counter circuits 23 and 25 continuously count the number of input pulses for every input location and angle. Here, gamma rays emitted from an external radiation source 14 generate K-X rays through photoelectric effect produced in the collimator of the camera head 11. The dosage of the K-X rays mixing into a counted value by the counter circuit 25 is estimated by a processor 29 for correcting K-X rays in accordance with a measured value by the counter circuit 23 and is reduced from the measured value by the counter circuit 25.
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