Potential for biomedical applications of positron annihilation lifetime spectroscopy (PALS)

Abstract

Positron Annihilation Lifetime Spectroscopy (PALS) allows examining structure of materials in nano and sub-nanometer scale. This technique is based on the lifetime and intensity of ortho-positronium atoms in free volumes of given structures. It is mostly used for studies in material sciences, but it can also be used for in vivo imaging of the cell morphology as proposed in [1], [2]. Cancer cells are characterized by an altered macro structure in comparison to normal cells, thus the main objective of these studies is to compare if these differences can be detected on sub-nanometer level with PALS technique. First studies on standard PAL spectrometers conducted by Jean [3],[4] and J-PET collaboration [5], [6], give promising results showing differences between normal and cancer tissues.This perspective will allow for simultaneous determination of early and advanced stages of carcinogenesis, by observing changes in biomechanical parameters between normal and tumour cells, and standard PET examination, which can be performed with the Jagiellonian Positron Emission Tomograph (J-PET), a multi-purpose detector used for investigations with positronium atoms in life-sciences as well as for development of medical diagnostics. Results of first PALS measurement of cardiac myxoma, with J-PET detector is presented in this paper. Obtained o-Ps lifetime for tumor tissue is equal to 2.03(01)[ns] and its intensity 25.7(1)%.