| 摘要 |
PURPOSE:To output a digital value of the number of bit necessary for obtaining a specified spatial resolution irrelevant to energy by using a voltage corresponding to energy of radiation as reference voltage in the A/D conversion of a photoelectric conversion output. CONSTITUTION:A scintillation light detection signal through a photoelectric converter forming a photomultiplier is inputted into a corresponding sequential comparison type A/D converter 71. In the sequential comparision processing with the converter 71, a digital output of a sequential bit from MSB of a register 19 and a voltage proportional to radiation energy based on the output of the photomultiplier as reference voltage are inputted into a D/A converter 18 and converted into analog from digital with a comparison reference voltage applied to a comparator 17 varying according to the radiation energy. The number of bit of the digital data thus processed lessens as the radiation energy becomes larger and thus, a digital value of the number of bit required to obtain a specified spacial resolution is outputted. This simplifies the construction of the A/D converter/position computing circuit of a scintillation camera. |
