Evaluation of a photon counting Medipix3RX cadmium zinc telluride spectral x-ray detector

Abstract

We assess the performance of a cadmium zinc telluride (CZT)-based Medipix3RX energy-resolving and photon-counting x-ray detector as a candidate for spectral microcomputed tomography (micro-CT) imaging. It features an array of 128 × 128, 110-μm 2 pixels, each with four simultaneous threshold counters that utilize realtime charge summing. Each pixel's response is assessed by imaging with a range of incident x-ray intensities and detector integration times. Energy-related assessments are made by exposing the detector to the emission from an I-125 radioisotope brachytherapy seed. Long-term stability is assessed by repeating identical exposures over the course of 1 h. The high yield of properly functioning pixels (98.8%), long-term stability (linear regression of whole-chip response over 1 h of acquisitions: y ¼ −0.0038x þ 2284; standard deviation: 3.7 counts), and energy resolution [2.5 keV full-width half-maximum (FWHM) (single pixel), 3.7 keV FWHM (across the full image)] make this device suitable for spectral micro-CT.

Novel Detector Configurations in Cone-Beam CT Systems: A Simulation Study

“…According to Table 3, and under the simulation assumptions, semiconductors tend to have more satisfactory CNRs in the bone sphere than CsI:Tl. The above findings are indicative of the increased scientific interest in the CZT detector's evaluation for CT systems, especially in the area of photon counting CT [44,45]. In this context, a previous study, evaluating two CBCT system configurations (one with a CsI:Tl flat panel detector, while the other was based on a CZT semiconductor) resulted in a CNR increase of 1.48 for microcalcifications and 1.85 for iodine contrast enhancement, when CZT-based configuration was used, instead of the common CsI:Tl scintillator [46].…”

“…As far as noise artifacts [45,48] are concerned, in Figure 9, the beam hardening effect as a product of FBP reconstruction is clearly visible, hindering the visibility of low-contrast objects in the vicinity of high-Z objects (aluminum and glass). This can be avoided by using iterative reconstruction algorithms, as can be inferred from Figure 9b.…”

A Novel and Reliable Pixel Response Correction Method (DAC-Shifting) for Spectral Photon Counting CT Imaging

“…One example of a PCD chip is the Medipix3RX, which consists of 256 × 256 pixels with a pixel pitch of 55 µm and two threshold counters per pixel ( [4]). In spectroscopic configuration, 2 × 2 pixels are combined, resulting in a 110 µm pixel pitch and eight counters per pixel ( [5]). The chips can be tiled together to create a large field of view (FOV).…”