A complete 4DCT-ventilation functional avoidance virtual trial: Developing strategies for prospective clinical trials

• Authors: Timothy Waxweiler, University of Colorado; Leah Schubert, University of Colorado; Quentin Diot, University of Colorado; Austin Faught, University of Colorado; Kelly Stuhr, University of Colorado; Richard Castillo, Emory University; Edward Castillo, Beaumont Health System; Thomas Guerrero, Beaumont Health System; Chad Rusthoven, University of Colorado; Laurie Gaspar, University of Colorado; Brian Kavanagh, University of Colorado; Moyed Miften, University of Colorado; Yevgeniy Vinogradskiy, University of Colorado
• Journal Title: Journal of Applied Clinical Medical Physics
• Volume: Volume 18, Number 3
• Publisher: Wiley Open Access | 2017-05-01, Pages 144-152
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1002/acm2.12086
• Subjects: Health Sciences, Oncology; Health Sciences, Radiology
• Keywords: Science & Technology; Life Sciences & Biomedicine; Radiology, Nuclear Medicine & Medical Imaging; CT ventilation; functional imaging; lung cancer; PROTON THERAPY; IMAGE REGISTRATION; MOBILE CT

Abstract

Introduction: 4DCT-ventilation is an exciting new imaging modality that uses 4DCT data to calculate lung-function maps. Because 4DCTs are acquired as standard of care for lung cancer patients undergoing radiotherapy, 4DCT-ventiltation provides functional information at no extra dosimetric or monetary cost to the patient. The development of clinical trials is underway to use 4DCT-ventilation imaging to spare functional lung in patients undergoing radiotherapy. The purpose of this work was to perform a virtual trial using retrospective data to develop the practical aspects of a 4DCT-ventilation functional avoidance clinical trial. Methods: The study included 96 stage III lung cancer patients. A 4DCT-ventilation map was calculated using the patient's 4DCT-imaging, deformable registration, and a density-change-based algorithm. Clinical trial inclusion assessment used quantitative and qualitative metrics based on the patient's spatial ventilation profile. Clinical and functional plans were generated for 25 patients. The functional plan aimed to reduce dose to functional lung while meeting standard target and critical structure constraints. Standard and dose-function metrics were compared between the clinical and functional plans. Results: Our data showed that 69% and 59% of stage III patients have regional variability in function based on qualitative and quantitative metrics, respectively. Functional planning demonstrated an average reduction of 2.8 Gy (maximum 8.2 Gy) in the mean dose to functional lung. Conclusions: Our work demonstrated that 60-70% of stage III patients would be eligible for functional planning and that a typical functional lung mean dose reduction of 2.8 Gy can be expected relative to standard clinical plans. These findings provide salient data for the development of functional clinical trials.