2022-07-01 16:52


Conference: Bucharest University Faculty of Physics 2019 Meeting

Section: Biophysics; Medical Physics

Offline Adaptive Radiotherapy in Head and Neck cancer patients

Cristian CIOABA (1,2), Mihai Daniel SUDITU (2), Claudia CHILOM (1)

1) University of Bucharest, Faculty of Physics, Bucharest, Romania

2) “Sfântul Nicolae” Medical Center, Pitești, Romania


Head and neck cancer, adaptive radiotherapy

During radiotherapy (RT) significant anatomic changes occur in head and neck cancer patients either due the tumor shrinkage or weight loss caused by feeding problems. Thus, the actual dose distribution can be considerably different from the one calculated in the initial treatment plan. Adaptive radiotherapy (ART) can be defined as changing the treatment plan delivered to a patient based on observed anatomic changes and can occur at different timescales: offline between radiation therapy treatment sessions, online immediately before treatment delivery and in real time during treatment delivery. The purpose of this study was to evaluate the differences between planned and delivered dose and to quantify the benefits of using offline adaptive radiation therapy. For this purpose, ten patients which underwent one mid treatment ART re-planning were selected. First, the dose distribution was calculated on the ART computed tomography (CT) following fusion with the initial CT, using the initial beam geometry and contours, in order to show the actual dose distribution if the ART would have not been done. Second, the treatment plan was optimized on the ART CT using the new contours in order to compare dose distribution with and without ART. In conclusion, the anatomic changes resulted in significant dosimetric differences especially in the parotid glands, and to a lesser degree in the target and other critical structures. Thus, the main benefit of replanning is improved sparing of parotid glands.