Energy resolution of a photon-counting silicon strip detector

TL;DR

This study evaluates and optimizes the energy resolution of a photon-counting silicon strip detector for spectral mammography, identifying key factors affecting performance and potential improvements.

Contribution

It provides a detailed analysis of energy response factors and validates a cascaded detector model for spectral X-ray imaging in mammography.

Findings

Energy resolution ranges from DeltaE/E=0.12 to 0.26 in mammography.

Electronic noise and charge sharing are primary factors affecting resolution.

Anti-coincidence logic reduces charge sharing but impacts energy resolution.

Abstract

A photon-counting silicon strip detector with two energy thresholds was investigated for spectral X-ray imaging in a mammography system. Preliminary studies already indicate clinical benefit of the detector, and the purpose of the present study is optimization with respect to energy resolution. Factors relevant for the energy response were measured, simulated, or gathered from previous studies, and used as input parameters to a cascaded detector model. Threshold scans over several X-ray spectra were used to calibrate threshold levels to energy, and to validate the model. The energy resolution of the detector assembly was assessed to range over DeltaE/E = 0.12-0.26 in the mammography region. Electronic noise dominated the peak broadening, followed by charge sharing between adjacent detector strips, and a channel-to-channel threshold spread. The energy resolution may be improved substantially if these effects are reduced to a minimum. Anti-coincidence logic mitigated double counting from charge sharing, but erased the energy resolution of all detected events, and optimization of the logic is desirable. Pile-up was found to be of minor importance at typical mammography rates.