| 摘要 |
PURPOSE:To make the tone of an image uniform by detecting scintillation light which is generated in a scintillator with a photomultiplier which is divided into a plurality of groups, and computing the incident position of radiation. CONSTITUTION:An electric signal is outputted from the output terminal of a photomultiplier 16 of a detector 12 in correspondence with the incident position of a gumma ray. The signal is converted into a digital signal in an A/D converter 30. The signals are divided in a comparator 31 based on the magnitudes of the signal values. The signals are outputted as the position signals for the specified coordinates for every group comprising an X axis and a Y axis at the final stage in an encoder 32. To which group the output signal belongs is distinguished based on the signal from a group selecting circuit 27. When the distinguished signal and the position signals of specified coordinates are supplied into an absolute-coordinate-position computing circuit 28, the absolute- coordinate-position signals X and Y of the incident gamma ray are outputted from said circuit. Thus, the position coordinates of a plurality of incident radiations which are inputted at the same time can be computed accurately, and the density of an image can be made uniform.
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