A high resolution and high detection efficiency depth-encoding detector for brain positron emission tomography based on a 0.75 mm pitch scintillator array.

The quantitative accuracy and precision of brain positron emission tomography (PET) studies can be considerably improved using dedicated brain PET scanners with a uniform high resolution and a high sensitivity across the brain volume. One approach to building such a system is to construct the PET scanner using depth-of-interaction (DOI) encoding detectors with finely segmented and thick crystal arrays. In this paper, the performance of a DOI PET detector based on two 16 × 16 arrays of 2 × 2 mm2 SiPMs coupled to both ends of a 44 × 44 array of 0.69 × 0.69 × 30 mm3 polished LYSO crystals was evaluated at different temperatures (-9°C, 0°C, 10°C, and 20°C) for brain PET applications. The pitch size of the LYSO array is 0.75 mm. The flood histograms show that all the crystal elements in the LYSO array can be resolved except some edge crystals, due to the limited light sharing. The average energy resolution, average DOI resolution, and average timing resolution across crystal elements are 21.1 ± 3.0%, 3.47 ± 0.17 mm, and 1.38 ± 0.09 ns, respectively, which were obtained at a bias voltage of 56.5 V and a temperature of 0°C.