Evaluation of anatomic and dosimetric changes during simultaneously integrated boost volumetric modulated arc therapy for head and neck cancer

Farah Dirar Yousif, Baghdad radiation oncology and nuclear medicine hospital, Baghdad medical city, Baghdad, Iraq.Follow
Raad Hefdhi Abedtwfeq, Department of radiology, Al-Yarmuk teaching hospital, Baghdad, Iraq.Follow

Article Type

Original Study

Abstract

Background: Volumetric modulated arc therapy (VMAT) is the most commonly used radiotherapy (RT) technique for locally advanced head and neck cancers (HNC), concurrent with chemotherapy. Aim: This study aims to evaluate the anatomical changes that may arise in patients undergoing VMAT treatment. Methods: The study involved 20 patients with locally advanced HNC who received VMAT treatment concurrently with chemotherapy. Prior to the initiation of radiotherapy treatment, computed tomography (CT) simulation was conducted for all patients. The prescribed doses for the primary target (PTVP), high-risk lymph nodes (PTV60), and low-risk lymph nodes (PTV54) were 69.96 Gy, 60 Gy, and 54 Gy, respectively, administered in 33 treatment fractions using the simultaneous integrated boost (SIB) technique. Anatomical comparisons were made between CT1, CT2, and CT3, while dosimetric evaluations were performed between iplan, Rplan1, and Rplan2. Results: The analysis revealed a significant weight decrement in terms of anatomical changes in all patients. The gross tumor volume (GTV) decreased notably at CT2 in comparison to CT1. The GTV volume decreased significantly again at CT3. Additionally, there was a substantial reduction in the volume of the parotid glands. For dosimetric evaluation, most organs at risk experienced a noteworthy increase in the received dose. For target coverage, the D95% of the PTVP in the (iplan) was 97%, which significantly increased in Rplan1. Conclusion: Patients with HNC must undergo a new CT simulation during the RT course owing to significant anatomic changes that impact the plan quality. New plans (adaptive plans) should be implemented for a specific number of fractions to ensure the maintenance of initial plan quality.

Keywords

Adaptive Radiotherapy, Head and neck cancers, IMRT, VMAT, Radiotherapy

Recommended Citation

Dirar Yousif, Farah and Abedtwfeq, Raad Hefdhi (2025) "Evaluation of anatomic and dosimetric changes during simultaneously integrated boost volumetric modulated arc therapy for head and neck cancer," Iraqi National Journal of Medicine: Vol. 7 : Iss. 2 , Article 17.
Available at: https://doi.org/10.37319/