Assessment of a photon-counting detector for a dual-energy C-arm angiographic system:

Moiz Ahmad, Rebecca Fahrig, Leland Pung, Martin Spahn, Niko S. Köster, Silke Reitz, Teri Moore, Jang Hwan Choi, Waldo Hinshaw, Yan Xia, Kerstin Müller

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Purpose: This article presents the implementation and assessment of photon-counting dual-energy x-ray detector technology for angiographic C-arm systems in interventional radiology. Methods: A photon-counting detector was successfully integrated into a clinical C-arm CT system. Detector performance was assessed using image uniformity metrics in both 2D projections and 3D cone-beam computed tomography (CBCT) images. Uniform exposure fields were acquired to analyze projection images and scans of a homogeneous cylinder phantom were taken to analyze 3D reconstructions. Image uniformity was assessed over a broad range of imaging parameters. Results: Detector calibration greatly improved image uniformity, reducing image variation from 8.8% to 0.5% in an ideal scenario, but image uniformity degraded when imaging parameters varied strongly from values set at calibration: the tube voltage, low-high energy threshhold, and tube current had the greatest impact. Material discrimination and dynamic angiography capabilities were successfully demonstrated in separate phantom and in vivo experiments. Conclusion: The uniformity results identified major factors degrading image quality. The quantitative results will guide selection of calibration points to mitigate the loss of uniformity. The unique combination of dual-energy and fluoroscopy imaging capabilities with a flat-panel photon-counting detector may enable new applications in interventional radiology.

Original languageEnglish
Pages (from-to)5938-5948
Number of pages11
JournalMedical Physics
Issue number11
StatePublished - Nov 2017


  • C-arm
  • computed tomography
  • dual-energy
  • photon-counting
  • x-ray detectors


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