Patent ID: 7633057

Claim:
A diagnostic imaging apparatus comprising: an array of scintillating elements, each scintillating element emitting light scintillations in response to incident radiation, the scintillating elements exhibiting inherent radioactivity by emitting radiation of at least one characteristic energy; an array of photomultiplier tubes in optical communication with the array of scintillating elements, the photomultiplier tubes each generating a response to the light scintillations emitted from the scintillating elements in response to the radiation of the characteristic energy which photomultiplier tube response varies with time and among the photomultiplier tubes a gain memory that contains gain settings for each photomultiplier; a photomultiplier tube self-calibration processor that recalibrates gain settings for each of the photomultiplier tubes using the inherent radioactivity of the at least one scintillating element, the self-calibration processor determining a characteristic peak in the response detected by one of the photomultiplier tubes in a singles mode, and linearly adjusting the gain setting for the corresponding photomultiplier tube to correct positioning of the characteristic peak in the response signal, the self-calibration processor including a center filter that limits the detected scintillations to scintillations under a center of each photomultiplier tube.