Dosimetric Comparison between Intensity Modulated Radiation Therapy and Volumetric Modulated Arc Therapy in Head and Neck Cancer

Abstract

Background: Head and neck cancer remains a major global oncological burden and often requires highly conformal radiotherapy because target volumes are complex and lie close to critical organs. Intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) are both widely used for treatment planning in HNC. Target coverage, treatment delivery parameters, and organ-at-risk sparing were examined and compared between IMRT and VMAT programs in this study. Methods: This single-center paired dosimetric planning study included 46 patients identified as having head and neck cancer (HNC), underwent CT-based radiotherapy planning at the International Medical Center between June 2023 and June 2024. For each patient, both VMAT and IMRT plans were developed for a prescription dose of 70 Gy in 35 fractions over 7 weeks, and dosimetric parameters were analyzed and compared between the two techniques. Results: VMAT demonstrated significantly higher PTV coverage metrics than IMRT for D95%, D50% and D2% . D98%, the conformance index, and the homogeneity index showed no significant differences. VMAT significantly reduced treatment delivery time and monitor units. Dosimetric parameters for the evaluated OARs which stands for organ-at-risk, including the brainstem, spinal cord, optic structures, parotid glands, and cochleae, were comparable between the two techniques. Conclusion: Within the limits of this planning study, VMAT appears to offer at least comparable organ-at-risk sparing with improved target coverage and more efficient treatment delivery than IMRT in treatment of HNC patients .