(Thursday, 7/18/2019) 7:30 AM - 9:30 AM
Room: Stars at Night Ballroom 2-3
Purpose: To investigate the impact of radiation dose to the lung on pulmonary vasculature anatomy and analyze the response dependence on fractionation method.
Methods: A cohort of 32 patients were recruited as part of an IRB approved clinical trial analyzing pulmonary function following radiation therapy. Jerman vesselness filtration was performed on two sets of two 4DCTs taken before and 3 mo post-RT respectively. The filtration produced a vesselness map indicating the probability of a vessel being located in each voxel of the 4DCT. Using the known voxel size, an integration over the entire lung mask was taken to analyze the predicted volume of vessels in the lung at each timepoint. Additional analysis was done to compare the relationships between predicted vessel volume with the treatment fractionation scheme and PTV volume respectively.
Results: A statistically significant (p=0.017) decrease in vasculature was observed between pre-RT and 3-month follow-up scans for patients treated with standard-fractionation. On average, these patients experienced a 4.7 +/- 0.07 % decrease in vasculature volume. The hypo-fractionation group did not experience significant changes in vasculature 3 mo post-RT. The PTV volume showed weak correlation to the change in predicted vessel volume (R^2<0.04).
Conclusion: This work indicates anatomical reduction in pulmonary vasculature at 3 mo following standard-fractionation RT. Results from 6 and 12-months post RT imaging and correlation with contrast perfusion scans are needed to demonstrate these changes are permeant and correlated with changes in lung perfusion function. Ultimately, the hope is that this work will aid in developing a perfusion/dose response model derived from a 4D non-contrast scan that can be used for functional avoidance radiation therapy.
Funding Support, Disclosures, and Conflict of Interest: R01 CA166703
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