Adaptive radiotherapy in head and neck cancer: Evaluating volumetric and dosimetric changes for enhanced treatment quality

Abstract

Intensity-Modulated Radiotherapy (IMRT) is a modern type of external beam radiotherapy used to treat squamous cell carcinomas. However, challenges arise when performing initial treatment for head and neck cancer (HNC) To investigate volumetric and dosimetric changes during radiotherapy in patients with HNC and assess the impact of these changes on the quality of treatment. Data collected from 36 patients who performed head and neck radiation therapy at the Sohage Cancer Centre between 2020 and 2022 were analyzed. Volumetric changes in the tumor planning target volume (PTV), parotid gland (PG), and submandibular gland (SM) were measured at fractions 7, 14, and 21, respectively. This research also investigated target coverage with a D98% threshold, dose volume characteristics for organs at risk, and the impact of patient changes, specifically weight loss differences between the initial and replanning phases (WLi-r) and neck diameter (ND). The correlation between patients' weight loss (WL) and volumetric changes in parotid (vdP), submandibular (vdSM), and neck diameter (ND) was analyzed. The volume decreased in the PTV, right and left PG, and SM for all patients. The study revealed a significant increase in the PTV coverage (P = 0.001) and a decrease in the mean dose (Dmean) of the right and left PG. There was a strong correlation between weight loss (WL) and neck diameter (ND), as well as volumetric deformations in PTV (vdPTV), right parotid (vdRP), left parotid (vdLP), right submandibular (vdRSM), and left submandibular (vdLSM). Moreover, the maximum dose (Dmax) to the spinal cord (SC) and the mean dose (Dmean) to the submandibular gland (SM) decreased with p-values lower than 0.05. Based on the findings of this study, the application of adaptive radiotherapy at fractions 7, 14, and 21 contributed to increased target volume coverage and decreased doses to organs at risk in patients with head and neck cancer.