O B A V I J E S T
ANA MARIJA KOŽULJEVIĆ
održat će znanstveni kolokvij (doktorski seminar) iz Medicinske fizike pod naslovom
Development of the detector system for measuring polarization correlations of annihilation gamma
photons and investigation of its application in Positron Emission Tomography
Positron emission tomography (PET) is a functional imaging technique which is of great importance in medical diagnostics. The method is based on the measurements of the positron annihilation products – the two entangled gamma photons with energies of 511 keV and opposite momenta. These photons also have orthogonal polarizations, a property which has not yet been exploited by commercial PET systems. According to simulations studies, this property offers a possibility of improving the image quality through the reduction of the background, which lacks the correlation in the polarization. To explore this possibility experimentally, a novel PET demonstrator, with the possibility to measure gamma-ray polarizations, has been developed and commissioned. This device consists of four detector modules mounted on an aluminum ring, with an attached wooden platform. Each module consists of four detector matrices of 8 x 8 pixels of GaGG:Ce and/or LYSO:Ce with a detector pitch of either 2.2 mm or 3.2 mm. The modules thus formed consist of 16 x 16 pixels each, hence, the PET demonstrator has a total of 1024 pixels, which through rotation virtually form 16 trans-axial rings. The detectors were tested in the laboratory and evaluated for their sensitivity to measure the polarization correlations of the annihilation gamma-rays, as well as through in-silico experiments in Geant4 simulation environment. The device’s performance was investigated at the University Hospital Centre Zagreb, using clinically relevant sources. In this seminar, I will present an overview of the results of the measurements conducted at the UHC Zagreb, with a focus on line sources and the NEMA phantom. This includes the data quality assurance and data selection processes, particularly relating to the photoelectric interactions and Compton scatterings of the correlated photons in the detectors. The images reconstructed from the selected data will be shown, as well as the key characteristics determined from the images, such as spatial resolution for different interaction types and signal-to-noise ratios for various event selections.
Seminar će se održati u ponedjeljak 18. prosinca 2023. godine u 12:00 sati u predavaonici F-201 Fizičkog odsjeka Prirodoslovno-matematičkog fakulteta Sveučilišta u Zagrebu.
Pozivaju se studenti doktorskog studija Fizike, smjer Medicinska fizika, da prisustvuju seminaru, ako nisu spriječeni.
Voditelj smjera:
Doc. dr. sc. Tomislav Bokulić, v. r.
Pristupačnost
