First Prototyping of a Total-Body Small Animal PET with a 4-Layer DOI Detector

Recently, a total-body positron emission tomography (PET) scanner, which was developed by UC Davis, enabled the total-body dynamic molecular imaging with a subsecond temporal resolution in a human study. However, when it comes to small animal PET, the long axial field-of-view (FOV) causes a parallax error not only in the radial direction but also in the axial direction. In a previous simulation study, we demonstrated that a total-body small animal PET scanner with a 4-layer depth-of-interaction (DOI) detector can reduce the parallax error substantially. In this study, we present the first imaging results with the prototype total-body small animal PET (TBSAP) scanner. The proposed TBSAP scanner has an inner diameter of 155 mm and an axial length of 325.6 mm which can cover a rat whole-body. The TBSAP consists of 6 rings each of which has 10 DOI detectors Five of 6 rings are used since the detector calibration of the 6th ring has not been finished yet. Each DOI PET detector consists of a 4-layer Zr-doped gadolinium oxyorthosilicate (GSOZ) crystal array and an 8×8 array multi-anode PMT. Each crystal layer has a 16×16 array of GSOZ crystals (2.8×2.8×7.5 mm3) which yields a total crystal thickness of 30 mm. The PMT anode signals are multiplexed using a resistive network, and then digitized by the 8-bit DAQ system (Hamamatsu, Japan). The 2.2 mm rod of the Derenzo-like phantom can be resolved even with the 30 mm radial offset. The peak sensitivity of 16.7% is obtained at the center of the FOV. The parallax error along the radial and axial directions can be reduced by using the 4-layer DOI detector. In the near future, we will perform a real-time dynamic animal imaging study with the prototype PET scanner.2020 Virtual IEEE Nuclear Science Symposium and Medical Imaging Conferenc