A design of PET detector using microchannel plate PMT with transmission line readout

A computer simulation study has been conducted to investigate the design of a PET detector module. The detector unit consisted of a 24×24 array of pixelated LSO crystals, each was 4×4×25 mm³ in size, and two 102×102 mm² microchannel plate (MCP) PMTs coupled to both sides of scintillators. The crystal pitch was 4.25 mm and reflective media was inserted between crystals. The signals from MCP were readout using a transmission-line scheme. The optical photon inside scintillator was simulated by using the Geant4 package and the output signals of the MCP was formed by applying the electrical responses measured of the MCP to each individual detected photon. A experimental setup was built using a Photonis planacon MCP(XP85022) and a Transmission line board to measure the characteristics of MCP/TL. The measured single photoelectron response(SER) was fed to the simulation of the electrical signal. The responses to 511 keV gamma of the test setup were compared to the simulation results for the validation. The simulation study results showed an energy resolution of ~11% at 511 keV for the detector module. When using a 400-600 keV energy window, we obtained a coincidence timing resolution of ~323 ps FWHM and a coincidence detection efficiency of ~40% for normally incident 511 keV photons. The position resolution was measured to be ~4.25 mm. The readout at both ends of scintillator made it possible to infer depth of interaction(DOI) based on the energy asymmetry and time differences. The simulation study showed that the design is suitable for Time of Flight(TOF) PET with DOI capability.