A Geant4 Simulation Study Of A Xenon-Doped Liquid Argon, Full-Body, Time-of-Flight Positron Emission Tomography Scanner To Understand Its Performance And Noise Profile
Positron Emission Tomography (PET) is used to observe metabolic processes within living tissue. It works by reconstructing the annihilation origin of incident gamma rays produced by a positron emitting radiotracer. This field of nuclear imaging has seen a steady improvement of PET imaging largely due to the application of newer detection technologies and image reconstruction algorithms. However, current PET scanners possess a small field of view which limits the overall sensitivity. Increasing the sensitivity and using Time of Flight (TOF) information can help to improve the quality of PET scans. This thesis will outline a novel PET scanner design poised to expand the capabilities of PET imaging. 3Dπ is a Total-Body, TOF - PET scanner that uses Silicon Photomultipliers (SiPM) coupled with a Xenon-doped Liquid Argon (LAr+Xe) scintillator. This design was simulated using the Geant4 particle-matter monte carlo simulation tool-kit while following the National Electrical Manufacturers Association’s evaluation tests (2018) for performance assessment. The results presented here highlight a 20-fold increase in sensitivity compared to traditional scanners produces sub-centimeter spatial resolutions and can produce PET images from 15-30 second scans, faster than traditional non-full-body 30-35-minute scans. In addition to an evaluation of the performance, this thesis will cover the major sources of noise a detector such as this one experiences. Next, the noisy signals will be quantified by discriminating the energies of the incident gamma ray recorded by the scanner. Lastly, the datasets generated from the monte carlo simulation will be used to compare two image reconstruction algorithms in order to gauge the difference between an analytical algorithm and a noise driven iterative algorithm. With a LAr+Xe scintillator and solid-state photosensors, 3Dπ can use the precise TOF info of gamma rays to improve the localization of individual positron annihilations, and as one example benefit, provide low-dose PET scans for patients who may be at high risk for exposure to radiation such as expectant mothers and adolescent children.
PET, LAr, SiPM, Monte-Carlo, Simulation, Xenon, Argon, Gean4
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