Speaker
Description
During Positron Emission Tomography (PET), as much as 40% of annihilations happen through the formation of positronium inside the patient’s body. Its properties, such as the fraction of positronium annihilations into three photons (3γ/2γ), are highly influenced by the tissue’s submolecular architecture. This has led to the development of a novel PET imaging techniques - 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, capable of multi-photon detection, enables three-gamma imaging necessary for determining 3γ/2γ ratio. The aim of this work is to study the absorption of gamma quanta in simplified models approximating the human body, as well as in the XCAT human phantom. For this purpose, toy Monte Carlo (MC) simulations of positronium decays into 2γ and 3γ and photon absorption in the models were performed and compared with the results obtained with GATE MC simulation tool. 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, required for data correction.
