Positron Annihilation Spectroscopy of Oxygen Content Tissue-Equivalent Samples

M. Zarea, O. Kakueeb, B. Ghasemia, A. Biganehb aNuclear engineering school, Shahid Beheshti University, Daneshjoo Blvd, Velenjak St., P.O. Box 1983969411, Tehran, Iran bPhysics & Accelerators Research School, Nuclear Science and Technology Research Institute, North Karegar st., P.O. Box 14395-836, Tehran, Iran

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In this paper, the potential biomedical application of the positron annihilation spectroscopy for tumor imaging systems is investigated. The positron annihilation lifetime spectroscopy and coincidence Doppler broadening spectroscopy are performed for oxygen-content tissue-equivalent polymers to determine the oxygen sensing ability of positronium atoms for the detection of tissue hypoxia. The results of the coincidence Doppler broadening spectroscopy experiment confirmed that the measured momentum of the annihilated electrons varies in the presence of oxygen. The results of the positron annihilation lifetime spectroscopy showed that due to the quenching role of the oxygen in the positronium formation, the τ3 and I3 parameters are sensitive to the concentration of oxygen in the content. However, when the oxygen concentrations differ by less than 4%, factors such as chemical environments, nano-structures of the matter, free volumes, and areas around the molecule are the other main factors influencing the lifetime of the probes. So, using positronium as a biomarker for tissue hypoxia needs more data to support the technique.

DOI:10.12693/APhysPolA.142.367 topics: positron annihilation lifetime spectroscopy (PALS), positronium, tumor imaging, hypoxia