Detective quantum efficiency model of single-X-ray-photon counting hybrid pixel detectors

Abstract

A Detective Quantum Efficiency (DQE) model of single-X-ray-Photon Counting Hybrid Pixel Detectors (PC-HPDs) is presented. It applies to PC-HPDs based on semiconductor sensors such as silicon and CdTe pixel sensors. Charge-sharing effects are introduced in the expressions of imaging performance parameters such as large-area gain factor, presampling modulation transfer function and digital noise power spectrum, using the concept of threshold-dependent effective fill-factor. A simple X-ray induced charge distribution approximation is used to derive a practical formula for the threshold-dependent large-area gain factor, i.e. the integral X-ray spectrum which can be indirectly measured with a PC-HPD. This detector model was applied to standard synchrotron X-ray PC-HPDs: MEDIPIX3, PILATUS and XPAD detectors.

Detective quantum efficiency for photon-counting hybrid pixel detectors in the tender X-ray domain: application to Medipix3RX

“…For the low energies we assume a constant charge-sharing probability, which is given by the mean value of Table 1: P = 0.619. A similar result was reported with a different experimental method based on a fit of the threshold scan with an original mathematical model using Medipix3 with a 300 mmthick Si sensor and 17.4 keV X-rays (Marchal & Medjoubi, 2012). In this paper, the probability of charge sharing was estimated to be P = 0.64.…”

“…However, counting detectors can detect individual photon hits within a user-defined energy range, making it possible to achieve virtually noise-free X-ray images. For this reason, the already published methods to evaluate the image quality on counting detectors do not consider the influence of the electronic noise (Marchal & Medjoubi, 2012;Michel et al, 2006;Ponchut, 2006;Wernecke et al, 2014). The study of Wernecke et al (2014) presents similarities with the current work since it focuses on characterization of the in-vacuum Pilatus detector at low energies, down to 1.75 keV.…”

Quantitative evaluation method of the threshold adjustment and the flat field correction performances of hybrid photon counting pixel detectors

“…As detailed in section 2, the FPN decreases with increasing incident energy due to PRNU dependence on the charge sharing slope. For threshold energy set below half of the working energy, the charge sharing acts as a low pass filter on the image and therefore decrease the spatial resolution [11]. As it has been demonstrated in section 2.1, the signal to noise measurements permits an estimation of the threshold dispersion.…”

Analytical model of single-X-ray photon counting pixel-array detectors

“…When the threshold is set at 50% of the X-ray energy (T = E 0 /2) and when the charge is split between two pixels, the detector counts one count only and the fill-factor in x or y is unity (γ x = γ y = 1). The factor γ 0 can therefore be referred to as fill-factor at 50% threshold [13,14].…”