Image quality in Cherenkov positron emission tomographyRazdevšek, Gašper (Avtor) Dolenec, Rok (Mentor) TOF PETCherenkov radiationmulti-sided crystal readoutPbF$_2$Geant4/GATE Monte Carlo simulationCASToRNEMA NU 2-2018Positron emission tomography (PET) is an important medical imaging modality, and although the technology is well established, there are still opportunities as well as a demand for better PET systems. The detection of annihilation photons in PET is based on scintillation light detection, but an interesting alternative is detection based on Cherenkov photons. Dense Cherenkov radiators provide an opportunity for high gamma detection efficiency - due to their high stopping power and photofraction - and excellent coincidence time resolution (CTR). However, because only a few tens of Cherenkov photons follow a gamma interaction in the radiator, the detection efficiency and the energy resolution of a pure Cherenkov detector are an issue. This work explores the performance of PET scanners based on Cherenkov detectors through Monte Carlo simulations and aims to determine whether such scanners are clinically feasible. First, single PbF$_2$ crystal based detectors with different surface treatments and photo-detectors covering one or multiple crystal faces were studied. Then, the potential performance of a full-size Cherenkov PET scanner was investigated using the NEMA NU 2-2018 standard and compared with a reference scanner - Siemens Biograph Vision PET scanner. The simulations were performed on a super-computing network using GATE software, and CASToR software was used for (TOF-OSEM) image reconstruction. Cherenkov scanner with single-sided readout performed similarly, while multi-sided readout detector designs performed better than the reference scanner, thanks to their improved coincidence detection efficiency and CTR. This work demonstrates that even though pure Cherenkov scanners have basically no energy resolution, the scatter fraction of around 50\% is not prohibitively large, and images comparable to the state-of-the-art clinical PET scanner can be achieved. Cherenkov detectors are expected to perform even better in low-scatter environments - brain, breast, or preclinical imaging studies - and their potential for low cost could make them very interesting for total-body scanners.20232023-04-26 08:15:02Doktorsko delo/naloga145613sl