Calibration of video cameras to the coordinate system of a radiation therapy treatment machine

  • Scott W. Hadley
  • L. Scott Johnson
  • Charles A. Pelizzari
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1496)


There has been recent interest in using video cameras along with computer vision and photogrammetric techniques to aid in the daily positioning of patients for radiation therapy. We describe here a method to calibrate video cameras to the beam coordinate system of a radiation therapy treatment machine. Standard camera calibration relates the three-dimensional coordinate system of a calibration phantom to the two-dimensional image coordinates. Using a calibration phantom designed for simultaneous X-ray and video imaging, both types of images can be calibrated to a single coordinate system. A series of X-ray images of the calibration phantom is taken using the motion of the treatment machine. Camera calibration parameters derived from these images are used to find a transformation from the coordinate system of the calibration phantom to the beam coordinate system of the treatment machine. This transformation is applied to the video camera calibration to provide a camera calibration directly to the beam coordinates of the machine.


Compute Tomography Image Focal Spot Video Image Camera Calibration Treatment Room 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. 1.
    Kenneth G.A. Gilhuijs, Automatic verification of radiation treatment geometry, Ph.D. thesis, University of Amsterdam, 1995.Google Scholar
  2. 2.
    Markus Menke, Frank Hirschfeld, Thomas Mack, Otto Pastyr, Volker Sturm, Wolfgang Schegel, “Photgrammetirc accuracy measurements of a head holder system used for fractionated radiotherapy,” Int. J. Radiat. Oncol. Biol. Phys., vol. 29, no. 5, pp. 1147–1155, 1994.CrossRefPubMedGoogle Scholar
  3. 3.
    B.D. Milliken, S.J. Rubin, R.J. Hamilton, L.S. Johnson, G.T.Y. Chen, “Performance of a video-image-subtraction-based patient positioning system,” Int. J. Radiat. Oncol. Biol. Phys., vol. 38, no. 4, pp. 855–866, 1997.CrossRefPubMedGoogle Scholar
  4. 4.
    Roger Y. Tsai, “A versatile camera calibration technique for high-accuracy 3d machine vision metrology using off-the-shelf TV camera and lenses,” IEEE Journal of Robotics and Automation, vol. RA-3, no. 4, pp. 323–344, 1987.CrossRefGoogle Scholar
  5. 5.
    Paul P. Richard, Robot Manipulators, MIT Press, 1984.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Scott W. Hadley
    • 1
  • L. Scott Johnson
    • 1
  • Charles A. Pelizzari
    • 1
  1. 1.The Department of Radiation and Cellular OncologyUniversity of ChicagoChicago

Personalised recommendations