Simultaneous Integrated Boost (SIB): RapidArc and Tomotherapy Plan Comparison for Unilateral and Bilateral Neck Irradiation

Abstract

Aim: The aim of the present study was to compare simultaneous integrated boost (SIB) plans using volumetric modulated arc therapy (RapidArc®; RA) or tomotherapy (TT) for bilateral (BL) and unilateral (UL) treatment in head-and-neck cancer (HNC) patients.

Material and methods: Seventeen computed tomography scans (CTs) of 16 patients with SIB were replanned using TT and RA. We defined three groups: All, UL and BL, compared the dose distributions, homogeneity, conformity to planning target volume (PTV), organs at risk (OAR) and healthy tissue (HT) sparing. We evaluated a therapeutic-width index (TWI) based on PTV coverage and parotid gland (PG) sparing.

Results: PTV coverage for RA and TT was equivalent for all groups. UL irradiation resulted in similar doses to the HT for both techniques but TT achieved better sparing of spinal cord, larynx and contralateral PGs. TT provided better homogeneity. RA gave better conformity.

Conclusion: Both methods achieved clinically acceptable results for UL and BL treatment, RA with better dose conformity to elective PTV, TT with better OAR sparing and homogeneity.

Keywords: Head and neck cancer; dosimetric comparison; helical IMRT; unilateral neck; volumetric arc techniques.