Count Rate Corrections for the Plant Dedicated PET System phenoPET

PET imaging is widely used to perform clinical and preclinical studies. A rather new area is the field of plant research. PET allows the dynamic imaging of 3D carbon transport and allocation within plants shoot and root systems of plants. Here, a new system called phenoPET has been developed within the German Plant Phenotyping Network (DPPN) using Digital Photon Counters (DPC) by Philips (digital silicon photo multipliers). Those are organized in horizontal rings forming a Field of View (FOV) of 180mm diameter and 200mm height.The detected hits are arranged in time frames, which are written to disc via USB 3:0 with a maximum transfer rate of 375MBs−1. Preprocessing and coincidence sorting are done offline. To enable high dynamic range phenoPET can drop frames which are not saved on disc when the transfer rate comes to a limit.To compare carbon transport of different plants quantitative images are required. A preliminary normalization and random correction are implemented. In this context, count rate correction and dead time correction are mandatory to avoid quantitative bias. In a decay experiment the dead time of the DPCs reduces the rate of singles by up to 10% at an radioactivity of about 100MBq placed close to the center of the FOV. At this activity about 70% of the frames are dropped leaving a maximum single rate of about 2:5 • 105 cps on each module. Further count rate correction factors for coincidences due to missing frames are presented.