Related Experiment Video
Updated: May 24, 2026
Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
Published on: June 7, 2015
Technical note: suppression of artifacts arising from simultaneous cone-beam imaging and RF transponder tracking in
Gavin Poludniowski1, Steve Webb, Philip M Evans
1Joint Department of Physics, Royal Marsden NHS Foundation Trust, Surrey, UK. Gavin.Poludniowski@icr.ac.uk
Purpose:
Artifacts in treatment-room cone-beam reconstructions have been observed at the authors' center when cone-beam acquisition is simultaneous with radio frequency (RF) transponder tracking using the Calypso 4D system (Calypso Medical, Seattle, WA). These artifacts manifest as CT-number modulations and increased CT-noise. The authors present a method for the suppression of the artifacts.
Methods:
The authors propose a three-stage postprocessing technique that can be applied to image volumes previously reconstructed by a cone-beam system. The stages are (1) segmentation of voxels into air, soft-tissue, and bone; (2) application of a 2D spatial-filter in the axial plane to the soft-tissue voxels; and (3) normalization to remove streaking along the axial-direction. The algorithm was tested on patient data acquired with Synergy XVI cone-beam CT systems (Elekta, Crawley, United Kingdom).
Results:
The computational demands of the suggested correction are small, taking less than 15 s per cone-beam reconstruction on a desktop PC. For a moderate loss of spatial-resolution, the artifacts are strongly suppressed and low-contrast visibility is improved.
Conclusions:
The correction technique proposed is fast and effective in removing the artifacts caused by simultaneous cone-beam imaging and RF-transponder tracking.
