| 摘要 |
PROBLEM TO BE SOLVED: To improve counting rate characteristic when conducting positron imaging by having gamma cameras face opposite to each other and conducting concurrent counting. SOLUTION: Detection signals from radiation detectors 10, 20 arranged to be opposite to each other are guided to position operation circuits 11, 21 respectively, whereby a position signal and an unblank signal are obtained. A digital output signal of a counter 31 which counts up according to a reference clock signal is sent as a time signal to these position operation circuits 11, 21. The time signal when the detection signal is input is fetched, and added to the position signal or the like as an information CLK1, CLK2 for indicating an input time and is then output. A simultaneous counting circuit 32 decides on the simultaneity from these CLK1, CLK2.
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