Effects of respiration-induced density variations on dose distributions in radiotherapy of lung cancer.

Research output: Contribution to journalArticle

  • External authors:
  • Vanessa Mexner
  • Jochem W H Wolthaus
  • Marcel van Herk
  • Eugène M F Damen
  • Jan-Jakob Sonke


PURPOSE: To determine the effect of respiration-induced density variations on the estimated dose delivered to moving structures and, consequently, to evaluate the necessity of using full four-dimensional (4D) treatment plan optimization. METHODS AND MATERIALS: In 10 patients with large tumor motion (median, 1.9 cm; range, 1.1-3.6 cm), the clinical treatment plan, designed using the mid-ventilation ([MidV]; i.e., the 4D-CT frame closest to the time-averaged mean position) CT scan, was recalculated on all 4D-CT frames. The cumulative dose was determined by transforming the doses in all breathing phases to the MidV geometry using deformable registration and then averaging the results. To determine the effect of density variations, this cumulative dose was compared with the accumulated dose after similarly deforming the planned (3D) MidV-dose in each respiratory phase using the same transformation (i.e., "blurring the dose"). RESULTS: The accumulated tumor doses, including and excluding density variations, were almost identical. Relative differences in the minimum gross tumor volume (GTV) dose were less than 2% for all patients. The relative differences were even smaller in the mean lung dose and the V20 (

Bibliographical metadata

Original languageEnglish
JournalInternational journal of radiation oncology, biology, physics
Issue number4
Publication statusPublished - 15 Jul 2009