phenoPET: A dedicated PET Scanner for Plant Research based on digital SiPMs

In the frame of the German Plant Phenotyping Project (DPPN) we developed a novel PET scanner. In contrary to a clinical or preclinical PET scanner the detector rings of the Plant System are oriented in a horizontal plane. The final system will be equipped with three rings covering a Field of View (FOV) of 18 cm diameter and 20 cm axial height. One detector ring is formed by 12 modules. Each module contains four 8×8 pixel digital SiPM devices DPC-3200-22-44 (Philips Digital Photon Counting) connected to a PCB and four scintillator matrices with 16×16 individual LYSO scintillators. Crystal size is 1.85×1.85×10 mm3. The matrices are composed with both reflective and transparent contact faces between the crystals in order to optimize crystal identification. A cooling system keeps the detectors below 5°C and limits the dark count rate. Data are already preprocessed by the Cyclone FPGA (Altera) in the module and transmitted from there at 50MiB/s to the base board. The base board collects the data from all modules and allows coincidence detection performed on a Kintex-7 FPGA (Xilinx). Finally the data link to the computer system for image reconstruction is realized via an USB 3.0 connection. Due to the fast photodetectors the system is dedicated to work with rather high activities. Preliminary measurements showed a coincidence peak of 250 ps FWHM between two detector elements and an energy resolution ΔE/E = 12%. This paper will present first results from a one ring system with a FOV of 18 cm diameter and 6.5 cm axial height

phenoPET – Results from the Plant Scanner

Within the German Plant Phenotyping Network (DPPN), we developed a novel PET scanner based on Philips Digital Photon Counters (DPCs, or dSiPMs = digital Silicon Photomultipliers). The scanner is dedicated for plant research and provides functional information on carbon transport within the plant. To this end the detector ring is oriented horizontally. It provides a Field-of-View of 18 cm dia. and 20 cm in height. The read-out electronics cluster hits from different photodetector pixels when they originate from the same scintillation event. These single events are written via USB 3.0 with up to 300 MB/s to the computer system. Crystal identification, energy discrimination and coincidence detection is realized in software. The spatial resolution in the center Field-of-View (CFOV) could be estimated to approx. 1.6 mm from measurements of a dedicated hot rod phantom. Preliminary sensitivity measurements result in a peak sensitivity of 4.04% (ΔE = 250-750 keV) in the CFOV and a Coincidence Resolving Time of 298 ps could be achieved