The YAP camera: an accurate gamma camera particularly suitable for new radiopharmaceuticals research

The YAP Camera represents a refined research instrument in nuclear medicine and pharmacology because of its overall detection efficiency comparable to an Anger Camera and its submillimeter intrinsic spatial resolution. The YAP Camera consists of a YAP:Ce multicrystal matrix, whose pillars dimensions are 0.6 mm x 0.6 mm x 10 mm, optically coupled with a position sensitive PMT Hamamatsu R2486 and furnished with a parallel hole lead collimator 20 mm thick with holes diameter of 0.5 mm and septa of 0.15 mm. At this stage it is a miniature camera, with a field of view (FOV) of 40 mm x 40 mm and a total spatial resolution of 1.0-1.2 mm, currently used for radiotracers studies on small biological specimens. A detailed analysis of the detector position linearity and energy responses are presented in this work. The intrinsic spatial resolution is studied with three different single hole collimators (1.0, 0.3, and 0.2 mm), and a theoretical equation is presented. Three different parallel hole collimators are tested to evaluate the optimal hole and septa dimensions. Finally, it is demonstrated that two correction procedures are capable of recovering the image spatial homogeneity and of removing the statistical noise. Some phantom images show the importance of the small-field YAP Camera in the radiopharmacological research. Index Terms - Discrete sampling device, image correction procedure, miniature gamma camera, PSPMT, spatial resolution, YAP:Ce.