Marian Smoluchowski
Institute of Physics

Jagiellonian University

Bachelor thesis

Study of high-energy photons polarization in Compton scattering using the J-PET detector system

Supervisor: dr Magdalena Skurzok

download

abstract

Defence year: 2023

The purpose of this work is the study of the high-energy photons polarization in Compton scattering using the Jagiellonian Positron Emission Tomography scanner (J-PET), more specifically finding the distribution of an angle between incoming and scattered photons polarization planes which opens the door for the polarization studies. Although polarization itself is a well studied phenomenon, until now it was only possible to investigate it in a narrow range of energies, using optical methods. J-PET detector, due to its unique construction, allows the registration of high-energetic gamma quanta emitted by the radioactive source and coming from the electron-positron annihilation and also their multiple scatterings. It enables to determine the direction of photons momentum vectors, thus the directions of their polarization. In this work three main types of analysis were performed, differing in the energy and origin of the incoming photons: (i) electron-positron annihilation photons, with the energy of 511 keV, (ii) already scattered photons, found between two interactions in the detector with an unknown energy, (iii) 22Ne de-excitation photons, with the energy of 1275 keV. Future measurements of the polarization will allow deeper understanding of the other phenomena, such as quantum entanglement or testing discrete symmetries in the leptonic sector.

Publications

ARTICLES

1. Development of correction techniques for a J-PET scanner
   M. Das, R. Bayerlein, S. Sharma, S. Parzych, S. Niedźwiecki, R. Badawi, E. Yitayew Beyene, N. Chug, C. Curceanu, E. Czerwiński, K. Valsan Eliyan, B. Głowa, A. Hubalewska-Dydejczyk, K. Kacprzak, T. Kaplanoglu, K. Kasperska, G. Korcyl, A. Khreptak, K. Kubat, D. Kumar, E. Lisowski, F. Lisowski, J. Mędrala-Sowa, S. Moyo, W. Mryka, M. Opalińska, P. Pandey, M. Rädler, M. Skurzok, A. Sowa-Staszczak, B. A. Spencer, P. Tanty, K. Tayefi Ardebili, A. Kunimmal Venadan, E. Stępień, P. Moskal
   download

   abstract

   Bio-Algorithms and Med-Systems 20 (2024)
   Objective: Positron Emission Tomography (PET) is a widely used medical imaging technique that allows for non-invasive imaging of metabolic processes. However, traditional PET scanners rely on costly inorganic scintillators, which limit their accessibility ? especially in light of emerging long axial field-of-view devices. The modular J-PET scanner, an innovative alternative, uses 50-cm long plastic scintillator strips, offering a cost-effective and modular solution. In this study, we develop and assess the PET data correction techniques required for quantitative image reconstruction. Methods: We present methods for attenuation correction, random coincidence correction using the Delayed Time Window (DTW) technique, and scatter correction based on Monte Carlo simulations. Phantom studies using the NEMA IQ phantom were performed to qualitatively evaluate these corrections. Results: The results demonstrate that our implemented corrections for attenuation, randoms, and scattered coincidences successfully improve the uniformity of tracer distribution in homogenous volumes and significantly reduce undesired activity in cold regions. Despite limitations in sensitivity and axial resolution, the applied correction techniques effectively enhance image quality, providing promising results for future applications. Conclusions: These findings highlight the potential of the modular J-PET system to offer affordable PET imaging and to pave the way towards a total-body PET scanner based on plastic scintillators. Future work will focus on quantitative validation and the implementation of these corrections for human subject imaging.