| 摘要 |
PROBLEM TO BE SOLVED: To improve uniformity in the distribution of detection sensitivity in the area of a visual field by a method wherein the central point of a light- receiving face of a gammaray detector in the end of a detector array and the central point of the light-receiving face of an adjacent gamma-ray detector are disposed at a specified distance from each other. SOLUTION: In a detector array 210, the positions of the centers of the respective light-receiving faces of gamma-ray detectors 211 and 212 and 21n -1 , and 21n are disposed at a distance L from each other respectively. Besides, the positions of the centers of the respective light-receiving faces of gamma-ray detectors 21k and 21k+1 (k=2, 3...n-2) are disposed at a distance L' from each other. So with a detector array 220. In the detector arrays 210 and 220 wherein the light-receiving faces of the detectors 21k and 22k (k=1, 2, 3...n) in the direction of arrangement have a width W respectively, these detectors are so disposed as to satisfy the relationships of L<=2W and L<L'<=2L. When annihilation of an electron-positron pair occurs in a portion 110 of integration of a radioactive isotope in an object 100 of measurement, a pair of photons (gamma rays) are generated consequently and detected.
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