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 3×3×10 mm³ crystals-pixels and a 5" diameter Hamamatsu R3292 position sensitive photomultiplier tube (PSPMT). After the PSPMT\´s readout was optimized a resolution of about ~3 mm@140 keV was obtained using only fourteen (7x,7y) anode wire sections in lieu of the standard 28×28 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 ^99mTc 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