Exploiting tumor position differences between deep inspiration and expiration in lung stereotactic body radiation therapy planning

Christina Huang, Kevin Shiue, Greg Bartlett, Namita Agrawal, Mona Arbab, Peter Maxim, Colleen DesRosiers, Todd Mereniuk, Susannah Ellsworth, Ryan Rhome, Jordan Holmes, Mark Langer, Richard Zellars, Tim Lautenschlaeger

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: We demonstrate proof of principle that normal tissue doses can be greatly reduced in lung stereotactic body radiation therapy (SBRT) for mobile tumors, if the delivered dose is split between opposite respiratory states. Methods: Patients that underwent 5 fraction lung SBRT at our institution and had deep inspiration breath hold (DIBH) and free breathing 4D computed tomography scans were included. Volumetric modulated arc therapy plans were generated on both respiratory phases and a third composite plan was generated delivering half the dose using the DIBH plan and the other half using the expiratory phase plan for each fraction. Computed tomography scans for the composite plan were fused based on ribs adjacent to the tumor to evaluate the dose volume histogram of critical structures. Results: Four patients with 4 total tumors had requisite planning scans available. Tumor size was between 0.7 to 2.9 cm and tumor movement 1.4 to 2.9 cm. Median reduction in the chest wall (CW) V30Gy for the composite plan was 74.6% (range 33.7 to 100%), 76.9% (range 32.9 to 100%), and 89.3% (range 69.5 to 100%) compared to the DIBH, expiration phase, and free breathing plans, respectively. Median reduction in CW maximum dose for the composite plan was 23.3% (range 0.27% to 46.4%), 23.5% (range 3.2 to 48.2%), and 23.4% (range 0.27% to 48.4%) compared to the DIBH, expiration phase, and free breathing plans, respectively. Greater reduction in CW maximum dose was observed when patients had no overlap in planning target volumes between DIBH and expiration phases (median reduction 43.9% for no overlap vs 2.7% with overlap). Between all plans, lung V20Gy absolute differences were within 1.3%. For 2 of 4 patients, the composite plan met constraints for 3 fraction SBRT, while standard plans did not. Conclusions: We conclude that composite DIBH-expiration SBRT planning has the potential to improve organ at risk sparing.

Original languageEnglish (US)
Pages (from-to)293-297
Number of pages5
JournalMedical Dosimetry
Volume45
Issue number3
DOIs
StatePublished - Sep 1 2020

Keywords

  • Motion management
  • Nonsmall cell lung cancer
  • Organ-at-risk sparing
  • Stereotactic body radiation therapy
  • Thoracic tumors

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Oncology
  • Radiology Nuclear Medicine and imaging

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