Dosimetric effects of intrafractional isocenter variation during deep inspiration breath-hold for breast cancer patients using surface-guided radiotherapy

Research output: Contribution to journalArticle

Abstract

The aim of this study was to investigate potential dose reductions to the heart, left anterior descending coronary artery (LAD), and ipsilateral lung for left-sided breast cancer using visually guided deep inspiration breath-hold (DIBH) with the optical surface scanning system Catalyst™, and how these potential dosimetric benefits are affected by intrafractional motion in between breath holds. For both DIBH and free breathing (FB), treatment plans were created for 20 tangential and 20 locoregional left-sided breast cancer patients. During DIBH treatment, beam-on was triggered by a region of interest on the xiphoid process using a 3 mm gating window. Using a novel nonrigid algorithm, the Catalyst™ system allows for simultaneous real-time tracking of the isocenter position, which was used to calculate the intrafractional DIBH isocenter reproducibility. The 50% and 90% cumulative probabilities and maximum values of the intrafractional DIBH isocenter reproducibility were calculated and to obtain the dosimetric effect isocenter shifts corresponding to these values were performed in the treatment planning system. For both tangential and locoregional treatment, the dose to the heart, LAD and ipsilateral lung was significantly reduced for DIBH compared to FB. The intrafractional DIBH isocenter reproducibility was very good for the majority of the treatment sessions, with median values of approximately 1 mm in all three translational directions. However, for a few treatment sessions, intrafractional DIBH isocenter reproducibility of up to 5 mm was observed, which resulted in large dosimetric effects on the target volume and organs at risk. Hence, it is of importance to set tolerance levels on the intrafractional isocenter motion and not only perform DIBH based on the xiphoid process.

Details

Authors
Organisations
External organisations
  • Skåne University Hospital
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Radiology, Nuclear Medicine and Medical Imaging

Keywords

  • Breath hold, Intrafractional isocenter variation, Optical surface scanning, Treatment planning
Original languageEnglish
Pages (from-to)25-38
JournalJournal of Applied Clinical Medical Physics
Volume19
Issue number1
Early online date2017 Nov 15
Publication statusPublished - 2018 Jan
Publication categoryResearch
Peer-reviewedYes

Related research output

Anneli Edvardsson, 2018 Sep, Lund: Lund University, Faculty of Science, Department of Medical Radiation Physics. 170 p.

Research output: ThesisDoctoral Thesis (compilation)

View all (1)