Program Information
Clinical Application of a Lung Function Planning Technique Designed to Improve Toxicity
J Bayouth1*, T Patton1 , S Gerard2 , G Christensen2 , A Baschnagel1 , J Reinhardt2 , (1) University of Wisconsin, Madison, WI, (2) University of Iowa, Iowa City, IA
Presentations
SU-E-605-2 (Sunday, July 30, 2017) 1:00 PM - 1:55 PM Room: 605
Purpose: Clinical implementation of a treatment planning methodology to achieve reduction of lung tissue damage following radiation therapy for non-small cell lung cancer.
Methods: Thirteen subjects were accrued to an IRB approved randomized prospective clinical trial. 4D computed tomography (4DCT) datasets were acquired and deformable image registration was used to create ventilation maps. Our previously reported predictive dose-response model was used to identify dose limits within each region of the lung for each subject. Functional-based ROIs were created for each lung region predicted to experience a > 10% reduction in tissue elasticity at dose levels of 10, 20, 30, 40, 50, and 60 Gy. Dose volume constraints were implemented for each subject and two plans were generated, conventional planning and optimization based on functional avoidance. Dose objectives were established for each ROI at each dose level. Patient treatment was randomized to either the conventional or experimental arm.
Results: Lung regions of dose-induced toxicity were predicted at each dose level: 10Gy (154 cc), 20 Gy (206 cc), 30 Gy (394 cc), 40 Gy (1570 cc), 50 Gy (1587 cc), and 60 Gy (1633 cc). Treatment plans designed to avoid these regions reduced the ROI volume receiving these doses by 28%, 31%, 46%, 28%, 27%, and 28%, respectively. Planning target volume (PTV) coverage remained above D95>95%, and organ-at-risk(OAR) constraints were maintained for all subjects.
Conclusion: Large regions of the lung demonstrate sensitivity to radiation, increasing in volume with increasing radiation dose. Using dose objectives based on predicted toxicity thresholds enabled substantial dose reduction in high functioning regions without compromise to dose coverage to the PTV or violation of OAR constraints.
Funding Support, Disclosures, and Conflict of Interest: NIH Grant number R01 CA166703
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