First ex-vivo positronium imaging of tissues with modular J-PET scanner using ⁴⁴Sc radionuclide

This study presents the first ex-vivo positronium imaging of human tissues using the modular J-PET scanner with the ⁴⁴Sc radionuclide. The ⁴⁴Sc isotope was produced via the ⁴⁴Ca(p, n)⁴⁴Sc nuclear reaction and used to perform positronium imaging of phantom composed of human adipose tissue, cardiac myxoma tissue, thrombi blood clot, and also porous polymer XAD4, and a certified reference material (CRM) made from fused silica. The experiment demonstrates the suitability of ⁴⁴Sc as a positron source for positronium imaging. The performance of J-PET for positronium imaging with ⁴⁴Sc was validated by proper reconstruction of the mean ortho-positronium lifetime for CRM material and XAD-4 polymer. The mean ortho-positronium (o-Ps) lifetimes determined for adipose tissue, cardiac myxoma tissues and thrombi were consistent with results of previous experiments. The study highlights the potential ⁴⁴Sc radionuclide for positronium lifetime imaging (PLI).