Patent ID: 8222608

Claim:
A PET scanner in which detector rings are arrayed in a multilayered manner so as to oppose each other in the body axis direction, wherein a predetermined number of detector units, each of which is made up of a predetermined number of detector rings, are arranged so as to give each other a clearance, a first ring set in which the clearance is less than or equal to a mean value of widths of two detector units forming each clearance and a second ring set constituted with a predetermined number of detector units, are arrayed apart so as to give a clearance which is less than or equal to a mean value of the width of the first ring set and that of the second ring set and is more than any clearance between the detector units constituting the first ring set, and a gantry is at least partially opened in accordance with at least some of the clearances between the detector units or between the ring sets, thereby imaging a field-of-view including the clearance and continuing in the body axis direction to an entire length of the first ring set and that of the second ring set.