Marian Smoluchowski
Institute of Physics

Jagiellonian University

Diploma thesis

Study of gamma quanta attenuation from positronium decays in phantoms

Supervisor: dr hab. Magdalena Skurzok

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abstract

Defence year: 2025

During Positron Emission Tomography (PET), as much as 40% of annihilations occur through the formation of positronium inside the patient?s body. Its properties, such as lifetime or the fraction of positronium annihilations into three photons (3?/2?), are highly influenced by the tissue?s submolecular architecture. This has led to the development of a novel PET imaging technique - positronium imaging - which provide additional insights into the imaged tissue. Conventional PET devices record only two annihilation photons and cannot assess the properties of positronium. However, the Jagiellonian PET (J-PET) scanner is capable of multi-photon detection, which allows for the measurement of the positronium lifetime as well as the detection of three-gamma decay, the latter being crucial for determining the 3?/2? ratio. The aim of this work is to study the absorption of gamma quanta emitted in the positronium decays in simplified models approximating the human body, as well as in the XCAT human phantom. For this purpose, toy Monte Carlo (MC) simulations of the p-Ps ? 2? and o-Ps ? 3? decays, and photon absorption in the models were performed. To validate the toy MC simulations, analogous simulations were also carried out using the GATE simulation toolkit. Additionally, the GATE simulations were extended to include more complex phantom models. Based on the simulations, the dependence of absorption probability of photons in the phantoms on the location of the decay point is determined. As a result of this research, we present absorption maps of para- and ortho-positronium decays, which form the foundation for developing attenuation maps required for tomographic image correction.

Bachelor thesis

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

Supervisor: dr Magdalena Skurzok

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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 POSTERS

1. First Positronium Imaging Using 44Sc With the J-PET Scanner: a Case Study on the NEMA-Image Quality Phantom
   Manish Das, Sushil Sharma, Ermias Yitayew Beyene, Aleksander Bilewicz, Jarosław Choiński, Neha Chug, Catalina Curceanu, Eryk Czerwiński, Kavya Valsan Eliyan, Jakub Hajduga, Sharareh Jalali, Krzysztof Kacprzak, Tevfik Kaplanoglu, Łukasz Kapłon, Kamila Kasperska, Aleksander Khreptak, Grzegorz Korcyl, Tomasz Kozik, Karol Kubat, Deepak Kumar, Anoop Kunimmal Venadan, Edward Lisowski, Filip Lisowski, Justyna Medrala Sowa, Simbarashe Moyo, Wiktor Mryka, Szymon Niedźwiecki, Piyush Pandey, Szymon Parzych, Alessio Porcelli, Bartłomiej Rachwał, Elena Perez del Rio, Martin Rädler, Axel Rominger, Kuangyu Shi, Magdalena Skurzok, Anna Stolarz, Tomasz Szumlak, Pooja Tanty, Keyvan Tayefi Ardebili, Satyam Tiwari, Rafał Walczak, Ewa Ł. Stępień, Paweł Moskal
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   abstract

   IEEE TRPMS 2025

   HEP: arXiv:2506.07230
   Positronium Lifetime Imaging (PLI), an emerging extension of conventional positron emission tomography (PET) imaging, offers a novel window for probing the submolecular properties of biological tissues by imaging the mean lifetime of the positronium atom. Currently, the method is under rapid development in terms of reconstruction and detection systems. Recently, the first in vivo PLI of the human brain was performed using the J-PET scanner utilizing the 68Ga isotope. However, this isotope has limitations due to its comparatively low prompt gamma yields, which is crucial for positronium lifetime measurement. Among alternative radionuclides, 44Sc stands out as a promising isotope for PLI, characterized by a clinically suitable half-life (4.04 hours) emitting 1157 keV prompt gamma in 100% cases after the emission of the positron. This study reports the first experimental demonstration of PLI with 44Sc, carried out on a NEMA-Image Quality (IQ) phantom using the Modular J-PET tomograph?the first plastic scintillators-based PET scanner.
2. muPPET: Investigating the Muon Puzzle with J-PET Detectors
   A. Porcelli, K. Valsan Eliyan, G. Moskal, N. Nasrin Protiti, D. L. Sirghi, E. Yitayew Beyene, N. Chug, C. Curceanu, E. Czerwiński, M. Das, M. Gorgol, J. Hajduga, S. Jalali, B. Jasińska, K. Kacprzak, T. Kaplanoglu, Ł. Kapłon, K. Kasperska, A. Khreptak, G. Korcyl, T. Kozik, D. Kumar, K. Kubat, E. Lisowski, F. Lisowski, J. Mędrala-Sowa, W. Mryka, S. Moyo, S. Niedźwiecki, S. Parzych, P. Pandey, E. Perez del Rio, B. Rachwał, M. Rädler, S. Sharma, M. Skurzok, E. Ł. Stępień, T. Szumlak, P. Tanty, K. Tayefi Ardebili, S. Tiwari, and P. Moskal
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   abstract

   Universe 11 (2025) 180
   The muPPET [muon Probe with J-PET] project aims to investigate the Muon Puzzle seen in cosmic ray air showers. This puzzle arises from the observation of a significantly larger number of muons on Earth's surface than that predicted by the current theoretical models. The investigated hypothesis is based on recently observed asymmetries in the parameters for the strong interaction cross-section and trajectory of an outgoing particle due to projectile-target polarization. The measurements require detailed information about muons at the ground level, including their track and charge distributions. To achieve this, the two PET scanners developed at the Jagiellonian University in Krakow (Poland), the J-PET detectors, will be employed, taking advantage of their well-known resolution and convenient location for detecting muons that reach long depths in the atmosphere. One station will be used as a muon tracker, while the second will reconstruct the core of the air shower. In parallel, the existing hadronic interaction models will be modified and fine-tuned based on the experimental results. In this work, we present the conceptualization and preliminary designs of muPPET.
3. 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
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   abstract

   Bio-Algorithms and Med-Systems vol. 20 (2024) 101
   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.

1. Studies of the absorption parameter 3gamma/2gamma in positronium decays
   K. Kasperska, M. Skurzok
   2nd Symposium on new trends in nuclear and medical physics

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2. Studies of the absorption parameter 3?/2? in positronium decays
   K. Kasperska,