1. A diagnostic imaging system, comprising: a stationary detector that is responsive to radiation emitted by a radiopharmaceutically doped organ tissue mass of a subject to be imaged; and an angular orientation-sensing member that is mounted on the detector and that determines the angular location of the detector relative to a patient bed, wherein the detector is a substantially fixed distance to the patient bed and the system associates each radiation event detected by the detector with the respective angular location of the detector and associates the respective angular location of the detector with a line of response and a circumferential position around the patient bed.