Bachelor thesis
Simulations of absorption in the brain of gamma quanta from positronium atoms
Supervisor: prof. Paweł Moskal
abstractPositronium imaging is a new method that can be used for PET scanning. This method allows not only to determine the location of the tumor, but also to analyze the structure of the tissue. What is important is how many gamma quanta from a positronium atom reach the detector. The main goal of this work is to study the absorption in the brain of gamma quanta from a positronium atom. The brain in this study is approximated by a sphere with water. The 3 gamma / 2 gamma ratio, a parameter that reflects the tissue structure, is determined. For this purpose, Monte Carlo simulations of positron decays into 2 gamma and 3 gamma and photon absorption in the brain and skull were performed. The simulation results were compared with theoretical calculations. The results of the percent events for which none of photons scattered in the head are as follows: 26.10 +/- 0.05% for para-positronium and 8.40 +/- 0.03% for ortho-positronium (absorption in the brain), 20.84 +/- 0.05% for para-positronium, 5.46 +/- 0,02% for ortho-positronium (absorption in the brain and in skull). The values of the 3 gamma / 2 gamma ratio from the simulation are: 0.322 +/- 0.002 for absorption in the brain and 0.262 +/- 0.002 for absorption in the brain and skull. The dependence of absorption probability of photons in the head on the location of positronium atom decay in the brain is determined.
CONFERENCE PROCEEDINGS POSTERS
- Feasibility study of positronium imaging with Biograph Vision Quadra and Modular J-PETS. Parzych, J. Baran, E. Yitayew Beyene, M. Conti, A. Coussat, N. Chug, C. Curceanu, E. Czerwiński, M. Dadgar, K. Dulski, K. Valsan Eliyan, A. Gajos, B. Hiesmayr, A. Jędruszczak, K. Kacprzak, M. Kajetanowicz, T. Kaplanoglu, Ł. Kapłon, K. Klimaszewski, G. Korcyl, T. Kozik, W. Krzemień, D. Kumar, G. Łapkiewicz, L. Mercolli, W. Migdał, S. Moyo, W. Mryka, S. Niedźwiecki, E. Pérez Del Río, L. Raczyński, A. Rominger, H. Sari, S. Sharma, K. Shi, S. Shivani, R. Shopa, M. Skurzok, W.M. Steinberger, E. Stępień, P. Tanty, F. Tayefi, K. Tayefi Ardebili, W. Wiślicki, P. Moskalpublished in: 2023 IEEE Nuclear Science Symposium, Medical Imaging Conference and International Symposium on Room-Temperature Semiconductor DetectorsPositronium Imaging is gaining interest as a new promising method that may improve the diagnostic specificity of Positron Emission Tomography. Recently, the first ex-vivo and in-vivo positronium lifetime images were demonstrated by means of the dedicated multi-photon J-PET system. The latest upgrades of the Biograph Vision Quadra (Siemens Healthineers) to the singles mode acquisition open the possibility of multi-photon imaging. In this simulation-based work, sensitivity of both systems has been assessed as a function of the energy window applied for registration of the prompt photon. The research was conducted using four radioisotopes: 124 I, 68 Ga, 44 Sc, 22 Na, which were chosen due to their medical or laboratory utilization. Simulations were performed with the GATE software. The result indicates that Biograph Vision Quadra provides about 400 times higher sensitivity with respect to the modular J-PET prototype used to demonstrate the first positronium images, assuming full energy acquisition of the prompt photon.
- Performance of NEMA characteristics of Modular J-PETF. Tayefi Ardebili, S. Niedźwiecki, J. Baran, E. Beyene, D. Borys, K. Brzezinski, N. Chug, A. Coussat, C. Curceanu, E. Czerwiński, M. Dadgar, K. Dulski, K. Eliyan, J. Gajewski, A. Gajos, B. Hiesmayr, A. Jędruszczak, K. Kacprzak, M. Kajetanowicz, T. Kaplanoglu, Ł. Kapłon, K. Klimaszewski, G. Korcyl, T. Kozik, W. Krzemień, D. Kumar, G. Łapkiewicz, W. Migdał, S. Moyo, W. Mryka, S. Parzych, E. Pérez del Río, L. Raczyński, S. Sharma, S. Shivani, R. Shopa, M. Skurzok, P. Tanty, K. Tayefi Ardebili, W. Wislicki, E. Stępień, P. Moskalpublished in: 2023 IEEE Nuclear Science Symposium, Medical Imaging Conference and International Symposium on Room-Temperature Semiconductor DetectorsThe Modular J-PET scanner, developed by the J-PET collaboration, is a new prototype PET scanner developed based on axially arranged plastic scintillators as a large axial field of view (50cm) affordable tomograph. In this study, the performance characteristics of the scanner were evaluated according to NEMA NU2-2018 standards using Monte Carlo simulation. In order to ensure the selection of true coincidence events, certain criteria were established. Specifically, each photon emitting from a single annihilation must deposit at least 200 keV within 4 ns of a coincidence time window. The preliminary results showed that the sensitivity profile peak was 4 cps/kBq at the center of the detector, While the scatter fraction was estimated to be 39% using the single slice rebinning algorithm. Spatial resolution was estimated around 4.5 mm in the radial and tangential direction and 18 mm in the axial direction.
- Normalization and scatter corrections for the J-PET scannerA. Coussat, W. Krzemień, J. Baran, S. Parzych, L. Raczyński, N. Chug, C. Curceanu, E. Czerwiński, M. Dadgar, K. Dulski, J. Gajewski, B. Hiesmayr, K. Valsan Eliyan, A. Jędruszczak, K. Kacprzak, A. Gajos, T. Kaplanoglu, Ł. Kapłon, K. Klimaszewski, T. Kozik, G. Łapkiewicz, G. Korcyl, S. Moyo, D. Kumar, W. Mryka, S. Niedźwiecki, S. Sharma, E. Pérez Del Río, S. Shivani, R. Shopa, P. Tanty, M. Skurzok, K. Tayefi, F. Tayefi, E. Stępień, W. Wiślicki, P. Moskalpublished in: 2023 IEEE Nuclear Science Symposium, Medical Imaging Conference and International Symposium on Room-Temperature Semiconductor DetectorsThe Jagiellonian PET scanner is a cost-effective large axial FOV Positron Emission Tomography technology that enables multi-photon imaging and is currently under development at the Jagiellonian University. The current 50 cm prototype, named Modular J-PET, is being investigated for various applications. It is well known that PET data can be affected by several effects during acquisition, such as scattered gamma photons or variations in detection efficiency. Consequently, achieving the reconstruction of images of satisfactory quality requires a set of corrections to be applied to each line-of-response. This summary discusses the implementation and performance of scatter and normalization corrections for the Modular J-PET, and their extension prior to the assembly of a total-body Jagiellonian PET scanner. Normalization correction is achieved using component-based normalization, a method particularly suitable for large scanners with a high number of lines-of-response. Scatter correction is achieved using an extension of the single scatter simulation technique that incorporates time-of-flight information. Reconstruction of reference phantoms based on Monte Carlo simulations highlight improvements in image quality. The application of normalization reduces the non-uniformity in the reconstructed image by a factor of 10 in the axial direction and 2 in the radial direction.
- Feasibility study of positronium imaging with Biograph Vision Quadra and Modular J-PETS. Parzych, J. Baran, E. Y. Beyene, M. Conti, A. Coussat, N. Chug, C. Curceanu, E. Czerwiński, M. Dadgar, K. Dulski, K. Valsan Eliyan, A. Gajos, B. Hiesmayr, A. Jedruszczak, K. Kacprzak, M. Kajetanowicz, T. Kaplanoglu, Ł. Kapłon, K. Klimaszewski, G. Korcyl, T. Kozik, W. Krzemień, D. Kumar, G. Łapkiewicz, L. Mercolli, W. Migdał, S. Moyo, W. Mryka, S. Niedźwiecki, E. Perez del Rio, L. Raczyński, A. Rominger, H. Sari, S. Sharma, K. Shi, Shivani, R. Y. Shopa, M. Skurzok, W. M. Steinberger, E. Ł. Stępień, P. Tanty, F. Tayefi, K. Tayefi, W. Wiślicki, P. Moskal2023 IEEE Nuclear Science Symposium and Medical Imaging Conference
- Simulations of absorption in the brain of gamma quanta from positronium atomsA. Jędruszczak1st Symposium on Theranostics, Cracow, Poland, October 2021
