Feasibility study of the positronium imaging with the J-PET tomograph

Abstract

A detection system of the conventional PET tomograph is set-up to record data from annihilation into two photons with energy of 511 keV, and it gives information on the density distribution of a radiopharmaceutical in the body of the object. In this paper we explore the possibility of performing the three gamma photons imaging based on ortho-positronium annihilation, as well as the possibility of positronium mean lifetime imaging with the J-PET tomograph constructed from plastic scintillators. For this purposes simulations of the ortho-positronium formation and its annihilation into three photons were performed taking into account distributions of photons’ momenta as predicted by the theory of quantum electrodynamics and the response of the J-PET tomograph. In order to test the proposed ortho-positronium lifetime image reconstruction method, we concentrate on the decay of the ortho-positronium into three photons and applications of radiopharmaceuticals labeled with isotopes emitting a prompt gamma. The proposed method of imaging is based on the determination of hit-times and hit-positions of registered photons which enables the reconstruction of the time and position of the annihilation point as well as the lifetime of the ortho-positronium on an event-by-event basis. We have simulated the production of the positronium in point-like sources and in a cylindrical phantom composed of a set of different materials in which the ortho-positronium lifetime varied from 2.0 ns to 3.0 ns, as expected for ortho-positronium created in the human body. The presented reconstruction method for total-body J-PET like detector allows to achieve a mean lifetime resolution of ∼40 ps. Recent positron annihilation lifetime spectroscopy measurements of cancerous and healthy uterine tissues show that this sensitivity may allow to study the morphological changes in cell structures.

Characterisation of Components of a Scintillation-fiber-based Compton Camera

“…Prototype systems for prompt-gamma and PET-gamma range monitoring were tested clinically and obtained satisfying precision of Bragg peak position monitoring on-line in the PBT treatment room [12][13][14]. At the Jagiellonian University in Kraków, a novel solution for diagnostic PET imaging, Jagiellonian-PET (J-PET) is being developed [15][16][17][18].…”

Development of J-PEM for Breast Cancer Detection and Diagnosis Using Positronium Imaging

“…The reconstruction of positronium lifetime requires determination of times of its creation and annihilation. These can be achieved when applying radiopharmaceuticals labeled with isotopes such as Scandium-44 which after emission of the positron changes into a daughter nucleus in an excited state [9]. A technique that combines PALS and PET in clinical use must enable determination of positronium parameters in a position-sensitive manner, and it needs to be scaled to work for living organisms.…”

“…Nonetheless, sensitivity and specificity can vary greatly depending on the spectrum of the disease in the studied group [7]. Section 3 details the concept behind the J-PEM and the possibilities of positronium imaging [8,9]. Section 4 presents preliminary results using Monte carlo simulation, performed using the GATE toolkit.…”

Towards Time Reversal Symmetry Test with o-Ps Decays Using the J-PET Detector

“…This spectroscopy technique has been a foundation in identifying the longlived radiative processes from the short-lived components in the decay of positronium atoms [3]. Recently a method combining PALS and Positron Emission Tomography was proposed and elaborated for the application in medical diagnostics [4,5]. This technique also aids the study of various physics phenomenon such as: quantum entanglement [6,7], search for mirror photons [8,9] and test for discrete symmetries in the charged leptonic sector [11].…”