Performance evaluation of dual-ended readout PET detectors based on BGO arrays with different reflector arrangements.

Dual-ended readout depth-encoding detectors based on bismuth germanate (BGO) scintillation crystal arrays are good candidates for high-sensitivity small animal positron emission tomography (PET) used for very-low-dose imaging. In this paper, the performance of three dual-ended readout detectors based on 15 × 15 BGO arrays with three different reflector arrangements and 8 × 8 silicon photomultiplier (SiPM) arrays were evaluated and compared. The three BGO arrays, denoted wo-ILG, wp-ILG, and wf-ILG, share a pitch size of 1.6 mm and thickness of 20 mm. Toray E60 with a thickness of 50 µm was used as inter-crystal reflector. All reflector lengths in the wo-ILG and wf-ILG BGO arrays were 20 and 18 mm, respectively; the reflectors in the wp-ILG BGO array were 18 mm at the central region of the array and 20 mm at the edge. By using 18mm reflectors, part of the crystals in the wp-ILG and wf-ILG BGO arrays worked as internal light guides. The performance of the three detectors were evaluated at a bias voltage of 41.0 V and a temperature of 23.6 oC. The results showed that the detector based on the wo-ILG BGO array provided the best flood histogram. The energy, timing and DOI resolutions of the three detectors were similar. The energy resolutions based on the wo-ILG, wp-ILG and wf-ILG BGO arrays were 27.2 ± 3.9 %, 28.7 ± 4.6 %, and 29.5 ± 4.7 %, respectively. The timing resolutions were 4.7 ± 0.5 ns, 4.9 ± 0.5 ns, and 5.0 ± 0.6 ns, respectively. The DOI resolution were 3.0 ± 0.2 mm, 2.9 ± 0.2 mm, and 3.0 ± 0.2 mm, respectively. Over all, the wo-ILG detector provided the best performance.