A study on position and energy correction of multi-pixel events in pixelated semiconductor detector for XFCT imaging

Abstract

X-ray fluorescence computed tomography (XFCT) is an emerging imaging modality that enables quantification of the distribution of high-Z elements, including gold, gadolinium, and iodine, in diverse biomedical applications, by specifically detecting the X-ray fluorescence (XRF) emitted from the target element. Pixelated semiconductor detectors such as Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CZT) sensors are particularly suited for XFCT imaging due to their high energy and spatial resolution capabilities. However, their performance degrades because of multi-pixel events, which occur when an incident photon deposits energy across multiple adjacent pixels. In this study, we implement corrections for the energy loss during charge sharing. Furthermore, for bi-pixel events occurring within the gadolinium K α energy and caused by the escape and re-capture of detector elements' x-ray fluorescence, we correct the interaction location. To validate the efficacy of the charge sharing energy loss correction and fluorescence escape events location correction, we utilized a PMMA phantom filled with Gadolinium saline solutions at concentrations ranging from 0 to 1.2mg/ml for XFCT imaging. The implemented corrections enhanced the contrast noise ratio in the gadolinium region. These improvements in XFCT imaging quality are useful for the preclinical investigation of precise tumor diagnosis and treatment using high atomic number element nanoparticles, and for other semiconductor detector-based imaging modalities.