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.
Bibliographical noteFunding Information:
The authors gratefully acknowledge funding support from the NIH Shared Instrument Grant S10 RR026714 supporting the zeego@StanfordLab, and Siemens Healthcare GmbH Advanced Therapies. The authors thank Mike Moseley for providing gadolinium contrast agent. Special thanks go to Yamil Saenz for his help with the in vivo pig imaging study.
© 2017 American Association of Physicists in Medicine.
- computed tomography
- x-ray detectors