C-arm calibration - Is it really necessary?

Ameet Kumar Jain, Michael An, Nicha Chitphakdithai, Gouthami Chintalapani, Gabor Fichtinger

Research output: Chapter in Book/Report/Conference proceedingConference contribution


C-arm fluoroscopy is modelled as a perspective projection, the parameters of which are estimated through a calibration procedure. It has been universally accepted that precise intra-procedural calibration is a prerequisite for accurate quantitative C-arm fluoroscopy guidance. Calibration, however, significantly adds to system complexity, which is a major impediment to clinical practice. We challenge the status quo by questioning the assumption that precise intra-procedural C-arm calibration is really necessary. Using our theoretical framework, we derive upper bounds on the effect of mis-calibration on various algorithms like C-arm tracking, 3D reconstruction and surgical guidance in virtual fluoroscopy - some of the most common techniques in intra-operative fluoroscopic guidance. To derive bounds as a function of mis-calibration, we model the error using an affine transform. This is fairly intuitive, since small amounts of mis-calibration result in predictably linear transformation of the reconstruction space. Experiments indicate the validity of this approximation even for 50 mm mis-calibrations. The problem is twofold: (a) C-arm intrinsic calibration; and (b) C-arm distortion correction. Using our theoretical and experimental analysis on mis-calibrated C-arms, we propose a hypothesis that indicates that intrinsic calibration might not be required for a family for surgical procedures. The framework also makes suggestions to the current work flow so as to further minimize the effect of any inherent mis-calibration. To address the problem of pose dependant distortion correction, we propose the use of a framework that can statistically study the maximum variation in distortion near a certain pose and then intra-operatively use an average correction. These theoretical derivations and experimental results make a strong case for the use of miscalibrated C-arms, obviating the cumbersome intra-operative calibration process, potentially boosting clinical applicability of quantitative fluoroscopy in many procedures. We also prove this hypothesis experimentally.

Original languageEnglish (US)
Title of host publicationProgress in Biomedical Optics and Imaging - Proceedings of SPIE
EditionPART 2
StatePublished - 2007
EventMedical Imaging 2007: Visualization and Image-Guided Procedures - San Diego, CA, United States
Duration: Feb 18 2007Feb 20 2007


OtherMedical Imaging 2007: Visualization and Image-Guided Procedures
Country/TerritoryUnited States
CitySan Diego, CA


  • 3D fluoroscopic guidance
  • C-arm calibration

ASJC Scopus subject areas

  • Engineering(all)


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