Towards real-time 2D/3D registration for organ motion monitoring in image-guided radiation therapy

C. Gendrin, J. Spoerk, C. Bloch, S. A. Pawiro, C. Weber, M. Figl, P. Markelj, F. Pernus, D. Georg, H. Bergmann, W. Birkfellner

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

3 Citations (Scopus)


Nowadays, radiation therapy systems incorporate kV imaging units which allow for the real-time acquisition of intra-fractional X-ray images of the patient with high details and contrast. An application of this technology is tumor motion monitoring during irradiation. For tumor tracking, implanted markers or position sensors are used which requires an intervention. 2D/3D intensity based registration is an alternative, non-invasive method but the procedure must be accelerate to the update rate of the device, which lies in the range of 5 Hz. In this paper we investigate fast CT to a single kV X-ray 2D/3D image registration using a new porcine reference phantom with seven implanted fiducial markers. Several parameters influencing the speed and accuracy of the registrations are investigated. First, four intensity based merit functions, namely Cross-Correlation, Rank Correlation, Mutual Information and Correlation Ratio, are compared. Secondly, wobbled splatting and ray casting rendering techniques are implemented on the GPU and the influence of each algorithm on the performance of 2D/3D registration is evaluated. Rendering times for a single DRR of 20 ms were achieved. Different thresholds of the CT volume were also examined for rendering to find the setting that achieves the best possible correspondence with the X-ray images. Fast registrations below 4 s became possible with an inplane accuracy down to 0.8 mm.

Original languageEnglish
Title of host publicationMedical Imaging 2010
Subtitle of host publicationVisualization, Image-Guided Procedures, and Modeling
EditorsKenneth H. Wong, Michael I. Miga
ISBN (Electronic)9780819480262
Publication statusPublished - 1 Jan 2010
EventMedical Imaging 2010: Visualization, Image-Guided Procedures, and Modeling - San Diego, United States
Duration: 14 Feb 201016 Feb 2010

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


ConferenceMedical Imaging 2010: Visualization, Image-Guided Procedures, and Modeling
Country/TerritoryUnited States
CitySan Diego


  • 2D/3D registration
  • General purpose computations on graphics hardware
  • Image guided radiation therapy


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