Evaluation of a EMCCD Detector for Emission-Transmission Computed Tomography

A prototype electron multiplying charged coupled device (EMCCD) based gamma camera is evaluated for emission-transmission computed tomography. The detector has an 8.2times8.2 mm² active sensor area with a 512times512 pixel array, and can be operated with a 3:1 fiber optic taper to expand the effective imaging area to approximately 25times25 mm² 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 ¹²⁵I and ^99mTc 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