A graphical method for determining the in-plane rotation angle in geometric calibration of circular cone-beam CT systems

Research output: Contribution to journalArticle

Abstract

It is well known that seven parameters completely describe a circular cone-beam geometry in either flat-panel X-ray computed tomography (CT) or single pinhole SPECT imaging. This paper considers the problem of determining one of the seven parameters only, the detector in-plane rotation or twist angle η. We describe a graphical procedure that can determine η independently of all other six parameters from a geometric calibration scan of point objects. Our method is exact in the ideal noise-free case and is general in that the other two out-of-plane detector rotation angles θ and φ can be nonzero. The calibration scan typically needs at least two point objects and an even number of projection views over a full 360° data acquisition. Under certain conditions, projection data truncation or a short scan acquisition of 180°+ fan angle can be accommodated without affecting the accuracy of the calibration result. The graphical method is equally applicable to rotational multipinhole SPECT geometry. In this case, the final result is averaged from the individual estimates considering each pinhole separately. We use computer simulations and a multipinhole SPECT experiment to demonstrate the accuracy and precision of the proposed method.

Original languageEnglish (US)
Article number6123208
Pages (from-to)825-833
Number of pages9
JournalIEEE transactions on medical imaging
Volume31
Issue number3
DOIs
StatePublished - Mar 1 2012

Keywords

  • Ellipse fitting
  • flat-panel X-ray computed tomography (CT)
  • geometric calibration
  • multipinhole
  • perspective geometry
  • pinhole single-photon emission computed tomography (SPECT)
  • vanishing point

ASJC Scopus subject areas

  • Software
  • Radiological and Ultrasound Technology
  • Computer Science Applications
  • Electrical and Electronic Engineering

Fingerprint Dive into the research topics of 'A graphical method for determining the in-plane rotation angle in geometric calibration of circular cone-beam CT systems'. Together they form a unique fingerprint.

  • Cite this