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

Jeffrey F. Marsh, Steven M. Jorgensen, David S. Rundle, Andrew J. Vercnocke, Shuai Leng, Philip H. Butler, Cynthia H. McCollough, Erik L. Ritman

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


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-μm2 pixels, each with four simultaneous threshold counters that utilize real-time 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 = - 0.0038x + 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.

Original languageEnglish (US)
Article number043503
JournalJournal of Medical Imaging
Issue number4
StatePublished - Oct 1 2018


  • Medipix
  • cadmium zinc telluride-based spectral microcomputed tomography
  • charge sharing
  • photon counting
  • x-ray microtomography

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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