Utilizing the VMAT Technique for Treating Head and Neck Cancer with Fixed Collimator Jaws

Abstract

Radiotherapy is the preferred option for early-stage head and neck cancer (HNC), especially in cases where surgery is not feasible or for patients with other co-morbidities. Head and neck radiation therapy is still improving for better management and control of the cancer. The volumetric modulated arc therapy (VMAT) technique ensures precise and accurate treatment delivery. This study presents a clinical comparison between plans with fixed collimator jaws and free collimator jaws generated head-and-neck VMAT plans made for clinical use. The study involved 10 patients with HNC, each receiving a dose prescription of 54.00 Gy and 63.00 Gy, administered in 30 fractions with daily doses of 1.8 Gy delivered to planning target volume (PTV) and 2.1 Gy delivered to boost target volume (BTV), respectively. All patients underwent treatment using the Electa Infinity linear accelerator, with the treatment plan generated using the Monaco treatment planning system. In our study, all cases were treated using two complete arcs, with one arc following a Gantry heading CW-180.1°-180° and the opposite arc following a Gantry heading CCW-180°-180.1°. Our findings indicate that employing the VMAT technique with one side of the collimator jaws fixed and the other side free, and in the opposite order, leads to a reduction of approximately 8-10 Gy in the maximum dose to the spine for all patients, compared to the collimator method, where both collimator jaws are free.

Keywords

• head and neck cancer
• radiotherapy
• collimator
• spinal cord