Functionality test of a readout circuit for a 1mm3 resolution clinical PET system

We are developing a 1mm³ resolution Positron Emission Tomography (PET) camera dedicated to breast imaging, which collects high energy photons emitted from radioactively labeled agents injected in the patients to detect molecular signatures of breast cancer. The camera consists of 8 × 8 arrays of 1 × 1 × 1mm³ lutetium yttrium oxyorthosilicate (LYSO) crystals coupled to position sensitive avalanche photo-diodes (PSAPDs). The camera is built out of 2 panels each having 9 cartridges. A cartridge houses 8 layers of 16 dual LYSO-PSAPD modules and features 1024 readout channels. Amplification, shaping and triggering is done using the 36 channel RENA-3™ chip. 32 of these chips are needed per cartridge, or 576 for the entire camera. The RENA-3™ needs functionality and performance validation before assembly in the camera. A Chip Tester board was built to ensure RENA functionality and quality, featuring a 20,000-cycle chip holder and the ability to charge inject each channel individually. Lab View software was written to collect data on all RENA-3™ channels automatically. Charge was injected using an arbitrary waveform generator. Software was written to validate gain, linearity, cross talk, and timing noise characteristics. Gain is tested using a linear fit, typical values of gain are 13 and -16 for positive and negative injected charges respectively. Timing analysis was based on analyzing the phase shift between U and V timing channels. A phase shift of 90 ± 5° and timing noise of 2ns were considered acceptable.