The effects of tumor motion on planning and delivery of respiratory-gated IMRT

Geoffrey D. Hugo, Nzhde Agazaryan, Timothy D. Solberg

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

The purpose of this study is to investigate the effects of object motion on the planning and delivery of IMRT. Two phantoms containing objects were imaged using CT under a variety of motion conditions. The effects of object motion on axial CT acquisition with and without gating were assessed qualitatively and quantitatively. Measurements of effective slice width and position for the CT scans were made. Mutual information image fusion was adapted for use as a quantitative measure of object deformation in CT images. IMRT plans were generated on the CT scans of the moving and gated object images. These plans were delivered with motion, with and without gating, and the delivery error between the moving deliveries and a nonmoving delivery was assessed using a scalable vector-based index. Motion during CT acquisition produces motion artifact, object deformation, and object mispositioning, which can be substantially reduced with gating. Objects that vary in cross section in the direction of motion exhibit the most deformation in CT images. Mutual information provides a useful quantitative estimate of object deformation. The delivery of IMRT in the presence of target motion significantly alters the delivered dose distribution in relation to the planned distribution. The utilization of gating for IMRT treatment, including imaging, planning, and delivery, significantly reduces the errors introduced by object motion.

Original languageEnglish (US)
Pages (from-to)1052-1066
Number of pages15
JournalMedical Physics
Volume30
Issue number6
DOIs
Publication statusPublished - Jun 1 2003

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Keywords

  • IMRT
  • Intensity modulated radiotherapy
  • Radiotherapy
  • Respiratory gating

ASJC Scopus subject areas

  • Biophysics

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