Preliminary evaluation of a novel energy-resolved photon-counting gamma ray detector

In this paper, we present the design and preliminary performance 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 × 4.4 cm, pixelated into 128 × 128 square pixels of 350 μm × 350 μm in size. The current detector consists of eight hybrids. Each hybrid has a CdTe crystal of 1.1 cm ×2.2 cm × 1 mm, bump-bonded onto a custom designed application-specific integrated circuitry (ASIC). The ERPC ASIC has 2048 channels arranged in a 32×64 array. Each channel is equipped with pre- and shaping-amplifiers, a discriminator, peak/hold circuitry and an analogue-to-digital convert (ADC) for digitizing the signal amplitude. In order to compensate for the pixel-to-pixel variation, two 8-bit DACs are implemented on each channel to allow fine tuning of the gain and offset. The ERPC detector is designed to offer a very high spatial resolution, a wide dynamic range of 12–200keV and an excellent 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.