Development of a novel energy-resolved photon-counting detector for gamma ray imaging applications

In this paper, we present the design and preliminary performance evaluation of a novel energy-resolved photon-counting (ERPC) detector for gamma ray imaging applications. The prototype ERPC detector has an active area of 4.4 cm x 4.4 cm, which is pixelated into 128 x 128 square pixels with a pitch size of 350 μm 350 μm. The current detector consists of multiple detector hybrids, each with a CdTe crystal of 1.1 cm x 2.2 cm x 1 mm, bump-bonded onto a customdesigned application-specific integrated circuit (ASIC). The ERPC ASIC has 2048 readout channels arranged in a 3264 array. Each channel is equipped with pre- and shaping-amplifiers, a discriminator, peak/hold circuitry, and an analog-todigital converter (ADC) for digitizing the signal amplitude. In order to compensate for the pixel-to-pixel variation, two 8-bit DACs are implemented into each channel for tuning the gain and offset. The ERPC detector is designed to offer a high spatial resolution, a wide dynamic range of 12-200 keV and a good energy resolution of 3-4 keV. The hybrid detector configuration provides a flexible detection area that can be easily tailored for different imaging applications. The intrinsic performance of a prototype ERPC detector was evaluated with various gamma ray sources, and the results are presented.