A phantom study on the effects of target motion in non-gated kV-CBCT imaging

Sriram Padmanaban, Raghavendiran Boopathy, Bhuvana Kunjithapatham, Prabakar Sukumar, Vivekanandan Nagarajan

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Abstract Kilo-voltage cone beam computed tomography (kV-CBCT) integrated with a linac can produce online volumetric and anatomical images for patient set-up and dosimetric analysis in adaptive radiotherapy. However CBCT is prone to motion artifacts. This study investigates the impact of target motion in CBCT imaging. To simulate respiratory movement, a dynamic phantom was moved in three-dimensions with a period of 4 s and two different amplitudes (PA1 and PA2). The targets of well defined geometries were made using wax. A reference image of the static target was achieved with fan beam CT. Using CBCT, the targets in static and dynamic modes were imaged under full-fan beam conditions. The length of average HU spread was reduced in range from 19.35 to 44.44% along the cranio-caudal direction of targets. The percentage volume loss of dynamic targets imaged using CBCT (for Hounsfield Units with window width -500 to 0) ranged from 14.35 to 30.95% for PA1 and 21.29 to 43.80% for PA2 in comparison with static targets imaged with fan beam CT. A significant loss of volumetric information may result for non-gated CBCT imaging of moving targets and may result in a systematic error in re-contouring when CBCT images are used for radiotherapy re-planning.

Original languageEnglish (US)
Pages (from-to)59-64
Number of pages6
JournalAustralasian Physical and Engineering Sciences in Medicine
Issue number1
StatePublished - Mar 2010
Externally publishedYes


  • Re-contouring
  • Systematic error
  • Target motion

ASJC Scopus subject areas

  • Biophysics
  • Biomedical Engineering
  • Radiology Nuclear Medicine and imaging
  • Physics and Astronomy(all)


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