Room: AAPM ePoster Library
Purpose: To compare photon and proton therapy radiation-induced inflammation by examining changes in the uptake of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) images of the ascending aorta (AA), descending aorta (DA), and aortic arch (AoA) for non-small cell lung carcinoma (NSCLC) patients.
Methods: Thirty-five (27 proton, 8 photon) consecutively definitively treated locally-advanced NSCLC patients prospectively enrolled on a trial in which they underwent FDG-PET/CT imaging before and 3 months after radiotherapy (RT) (prescription dose 60.0-66.6/1.8-2.0Gy) between 2013 and 2017 were assessed. The AA, DA, and AoA were contoured and a “rim” contour was created that encompassed the region 3mm-beyond and 3mm-inside the outer perimeter of each cardiac structure to represent the structure wall and remove influence of traveling blood. Statistical analysis was performed using student two-tailed t-tests.
Results: The mean dose (proton/photon) to the AA, AoA, and DA was 30.9/49.5Gy, 37.0/30.2Gy, and 17.4/20.6Gy, respectively. There was a numeric increase in mean standardized uptake value (SUV) for the AA, DA, and AoA (1.9%, 0.3%, and 1.3% for proton; 15.8%, 9.5%, and 15.5% for photon, respectively), with the increase being statistically significant (p<0.05) for AA and AOA in photon patients. There was a statistically significant difference between the photon and proton cohorts when comparing the delta (PostRT-PreRT) SUV for the AA and AoA. When examining the rim structures and dose received (portion of structure receiving greater than or less than 10Gy) there was an increase in mean SUV related to dose for the photon patients (average increase across structures 0.13SUV), which was not evident in the proton patients (0.01SUV); however, these results are not statistically significant.
Conclusion: Radiation-induced inflammation has been assessed through the increase of SUV in certain cardiac structures. Knowledge gained from a larger cohort and further analyses could aid in treatment planning to prevent future RT-induced cardiovascular complications.
Funding Support, Disclosures, and Conflict of Interest: Trial was funded, in part, by the McNichol Lung Cancer Research Philanthropy Fund
Not Applicable / None Entered.