An analytic, moment-based method to estimate orthopositronium lifetimes in positron annihilation lifetime spectroscopy measurements

TL;DR

This paper introduces an analytical, moment-based method to accurately estimate orthopositronium lifetimes in positron annihilation lifetime spectroscopy, improving stability and bias correction especially in low-count scenarios.

Contribution

The paper presents a novel analytical approach using moments of the time-difference histogram for estimating orthopositronium lifetime in PALS, enhancing stability and bias correction.

Findings

Method produces monotonic, stable estimates with sufficient data.

Bias correction and variability solutions improve accuracy in low photon count cases.

Applicable to hypoxia detection in PET scans.

Abstract

The presence of tumor hypoxia is known to correlate with poor patient prognosis. Measurement of tissue oxygen concentration can be challenging, but recent advancements using positron annihilation lifetime spectroscopy (PALS) in three-dimensional positron emission tomography (PET) scans have shown promise for hypoxia detection. In this work, a novel method for estimating the orthopositronium lifetime in PALS is presented. This method is analytical and uses moments of the time-difference histogram from photon arrival times. For sufficient statistical power, the method produces monotonic, stable estimates. For cases with a lower number of photon counts, the method was characterized and solutions are presented to correct for bias and estimation variability.