FTRAC - A robust fluoroscope tracking fiducial

Ameet Kumar Jain, Tabish Mustafa, Yu Zhou, Clif Burdette, Gregory S. Chirikjian, Gabor Fichtinger

Research output: Contribution to journalArticlepeer-review

65 Scopus citations


C-arm fluoroscopy is ubiquitous in contemporary surgery, but it lacks the ability to accurately reconstruct three-dimensional (3D) information. A major obstacle in fluoroscopic reconstruction is discerning the pose of the x-ray image, in 3D space. Optical/magnetic trackers tend to be prohibitively expensive, intrusive and cumbersome in many applications. We present single-image-based fluoroscope tracking (FTRAC) with the use of an external radiographic fiducial consisting of a mathematically optimized set of ellipses, lines, and points. This is an improvement over contemporary fiducials, which use only points. The fiducial encodes six degrees of freedom in a single image by creating a unique view from any direction. A nonlinear optimizer can rapidly compute the pose of the fiducial using this image. The current embodiment has salient attributes: small dimensions (3 × 3 × 5 cm); need not be close to the anatomy of interest; and accurately segmentable. We tested the fiducial and the pose recovery method on synthetic data and also experimentally on a precisely machined mechanical phantom. Pose recovery in phantom experiments had an accuracy of 0.56 mm in translation and 0.33° in orientation. Object reconstruction had a mean error of 0.53 mm with 0.16 mm STD. The method offers accuracies similar to commercial tracking systems, and appears to be sufficiently robust for intraoperative quantitative C-arm fluoroscopy. Simulation experiments indicate that the size can be further reduced to 1 × 1 × 2 cm, with only a marginal drop in accuracy.

Original languageEnglish (US)
Pages (from-to)3185-3198
Number of pages14
JournalMedical Physics
Issue number10
StatePublished - Oct 2005


  • C-arm
  • Fluoroscopy
  • Prostate brachytherapy
  • Reconstruction
  • Registration
  • Tracking

ASJC Scopus subject areas

  • Biophysics


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