| 摘要 |
PURPOSE:To eliminate the influence of scattered gamma rays to improve the quantitativity of position emission nuclide distribution by using crest data of a detector signal to eliminate contributions of scattered gamma rays from the counted value of simultaneous counting. CONSTITUTION:Signals of detectors 11-12 and 13-14 belonging to one detector group are amplified by a preprocessing circuit 2 to generate a timing signal 21 and a crest value signal 22. Signals 21 and 22 are inputted to a detector address encoder 3 to output a timing signal and detector address data to a timing signal output circuit 4, and the timing signal is outputted to a simultaneous counting circuit 7 when the crest value exceeds a set level. The signal 22 is inputted to a pulse height analyzing circuit 6 through an input circuit 5, and when the crest value exceeds the set level, a gate signal is outputted to the output circuit 4, and the signal from the circuit 7 is outputted to a memory circuit 8, and counted value '1' is added to the memory. Contributions of scattered gamma rays are eliminated from the simultaneous counted value.
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