An Investigation of the Feasibility of Using Adaptive Radiotherapy: A Real-World Experience

Objective: Using predetermined relative thresholds as benchmarks, the study aims to quantify the anatomical and dosimetric changes that patients with head and neck cancer undergoing intensity-modulated radiation treatment experience and assess the necessity of adaptive radiotherapy. Methods: 31 consecutive participants participated in this trial. For preliminary treatment planning and a halfway evaluation, two computed tomography (CT) scans were used. In order to apply primary dose calculation to midpoint CT, the study used rigid registration and contour transfer techniques. This resulted in a hybrid plan and an adaptive plan on the midpoint CT. Results: The PTV70, PTV60, and PTV54 volumes showed statistically significant volume reductions, according to the results. In the majority of patients, the parotid glands' volume showed volumetric reductions. Comparisons between hybrid and adaptive plans revealed notable differences in the maximal doses, while hybrid plans showed poorer dose coverage of the tumor regions. Conclusion: Replanning was mostly justified by anatomical variations that required a second CT scan and the use of a new immobilization mask. Before a replan is implemented, indicators such as a breach of 95% dose coverage for 95% of the tumor volume, maximum doses exceeding 50 Gy in the spinal cord and 59 Gy in the brainstem, and lateral neck displacement exceeding 1 cm from the initial position serve as benchmarks.