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Abstract

<b>101</b> <h3><b>Objectives</b></h3> In this work, we experimentally evaluate a prototype PET imaging setup, based on HPWF CdTe and CZT detectors, for ultrahigh resolution imaging of a mouse brain. The HPWF CdTe or CZT detectors utilize a simplified anode ASIC to readout the anode pixels to provide the X-Y address of gamma interactions, and uses digital waveform sampling circuitry to read the cathode waveform for deriving the energy, timing and (depth-of interaction) DOI. This offers advantages over typical CZT/CdTe pixel detectors for PET, including a) improved timing resolution over anode triggered pixelated detectors, b) improved energy resolution as the cathode signal is immune to charge sharing and loss from small pixels, c) simplified anode pixel readout circuitry for smaller pixels (100-200um), and d) excellent DOI resolution. <h3><b>Methods</b></h3> The PET setup consists of two HPWF CdTe detectors operated in coincidence around a rotary stage on top of a 3-D translation stage. Each HPWF detector has a 2mm x 2.2 cm x 1.1 cm CdTe crystal. The crystal has 2048 anode pixels, arranged in 64 x 32 array and each pixel is 350 µm x 350 µm, read out by a CMOS readout ASIC [1]. The cathode of the detectors is read with commercial waveform sampling circuitry (Gage CSE1242) for determining event energy, triggering, and DOI position. <h3><b>Results</b></h3> We have shown the energy (~5%), timing, and the spatial resolution of our setup. We have reconstructed point-source images that consist of 250 µm spherical sources spaced by 300 µm, and increasing by steps of 50 µm to 450 µm. Reconstructions without DOI, with DOI, and with both DOI and positron range correction are compared. We will further perform PET imaging of a mouse brain phantom and compare the results with images from a Siemens Inveon MicroPET. These results will be presented. <h3><b>Conclusions</b></h3> Our results have shown that HPWF detectors could offer excellent energy, timing and 3-D spatial resolution, which could lead to an ultra-high (potentially sub-300 µm) intrinsic resolution for mouse PET imaging.