Development of a small field of view scintimammography camera based on a YAP crystal array and a position sensitive PMT

We have developed a gamma imaging detector based on a 10 cm by 10 cm YAP crystal array made of 3/spl times/3/spl times/10 mm/sup 3/ crystals-pixels and a 5" diameter Hamamatsu R3292 position sensitive photomultiplier tube (PSPMT). After the PSPMT's readout was optimized a resolution of about /spl sim/3 mm@140 keV was obtained using only fourteen (7x,7y) anode wire sections in lieu of the standard 28/spl times/28 individual crossed-wires. Because individual crystals are well-separated and identified, a simple but effective position distortion correction is possible based on a flood measurement. Efficient scatter rejection is expected by placing individual energy windows on scintillation signals coming from each crystal-pixel. Measurements were made with thyroid phantoms and compressed as well as non-compressed breast phantoms with simulated lesions. The phantoms contained appropriate concentrations of /sup 99m/Tc emitting 140 keV gamma radiation. The detector combines good performance with small size and economical makeup. After final phantom tests we are planning to use it in clinical trials as a small field-of-view scintimammography camera.