Extended Field of View in Gamma Camera, Using New Approach for Position Calculation

摘要

The common Gamma camera, based on photomultiplier tubes (PMTs), utilizes the Anger algorithm to calculate the event positions. The Anger algorithm enables detection of events in a field of view (FOV) bounded by the center of the external PMTs. Events beyond this FOV cannot be distinguished. In common cameras, where 76mm diameter PMTs are used, a loss of over 76 mm in the FOV in each dimension occurs. In this work we present a new algorithm for event position calculation. This algorithm calculates a cost function based on the estimated PMTs distances from an event. The coordinates that minimize this cost function are chosen as the event position. In the current work we perform simulation and use the proposed algorithm to calculate the event positions. The results demonstrate that the FOV can be extended by 20-40mm in each dimension (depending on the detector design), using the proposed position calculation. Alternatively to increasing the FOV, the current algorithm enables usages of less PMTs while maintaining similar FOV, achieved with the Anger algorithm. The usage of the suggested algorithm results in smaller margins. Thus enabling better proximity to the patient that may improve the image quality.