We report on the development of a new high efficiency detector for small animal PET. The detector is based on a monolithic block of LSO pixelated using laser ablation technique. The laser processing allows pixelation with very narrow, 70 mum wide, inter-pixel gaps resulting in a substantially enhanced sensitivity when the detectors are operated in coincidence mode. This paper presents the first results of a detector module fabricated using this approach. Preliminary imaging data at 511 keV obtained by coupling the pixelated LSO to a position sensitive photomultiplier tube (PSPMT) and a position sensitive avalanche photodiode (PSAPD) are presented.

A prototype electron multiplying charged coupled device (EMCCD) based gamma camera is evaluated for emission-transmission computed tomography. The detector has an 8.2 x 8.2 mm(2) active sensor area with a 512 X 512 pixel array, and can be operated with a 3:1 fiber optic taper to expand the effective imaging area to approximately 25 x 25 mm(2) for small animal studies. We demonstrate the possibility of operating the camera in either charge integrating or single photon counting mode for pinhole SPECT with I-125 and Tc-99m sources. In photon counting mode, we show that energy discrimination can be used to distinguish between these two sources for dual isotope imaging. X-ray CT images of phantoms are taken without a collimator to evaluate the quality of the camera for transmission imaging.