English

Abstract

BACKGROUND The primary objective of this study is a dosimetric comparison for the feasibility of carotid sparing intensity modulated radiation therapy (CS-IMRT) for early glottis cancer. The planning target volume coverage and the spinal cord dose are compared in the 3-dimensional conformal radiotherapy (3DCRT) and IMRT plans. METHODS In this single reconcile study twenty-five patients who had been already treated for early-stage glottis cancer (T1, T2N0M0) from June 2015 to June 2021 with 52.5 Gy/15 fractions were included. All patients were simulated in supine position with an orfit shell and treatment planning computed tomography scans were obtained from the vertex to sternal angle with a 3-mm slice thickness. Treatment was executed with 3-DCRT plan and comparison was made with the newly created IMRT plan. The analysis was made regarding mean dose to the carotid arteries, volume of carotid artery receiving more than 25 Gy (V25), 35 Gy (V35), 50 Gy (V50), planning target coverage and doses to organ at risk. RESULTS The dose to carotids was significantly higher in the 3-DCRT plan compared with the IMRT plan (p=0.004). For target coverage the volume receiving 95% of the dose was significantly higher in IMRT plan (p=.001). The dose to the spinal cord was higher-in the IMRT plan (p=.001) compared to 3-DCRT plan. CONCLUSIONS IMRT maintains target volume coverage with significant reduction in carotid artery dose. This reduces the incidence of cerebrovascular accidents by decreasing the radiation induced carotid artery stenosis, thereby improving the quality of life of patients. KEY WORDS CS-IMRT, 3D-CRT, Mean Carotid Dose