Dosimetric comparison of helical tomotherapy and volume-modulated arc therapy for upper thoracic esophageal carcinoma

Abstract

Objective To compare the dosimetric differences between helical tomotherapy (HT) and volume-modulated arc therapy (VMAT) in the treatment of upper thoracic esophageal carcinoma (UTEC). Methods A total of 10 patients with UTEC were randomly selected. HT plan and double-arc VMAT plan were designed and optimized for each patient. The prescription dose was 50 Gy/30 fractions for gross target volume (GTV), 66 Gy/30 fractions for planned target volume (PTV). The dose distribution and conformal index (CI), homogeneity index (HI) of target volume, the D1%, D5%, D95%, D99%, and dose of organ at risk (OAR) were analyzed by using the dose volume histogram (DVH). The monitor units and delivery time were also evaluated. Results For GTV and PTV, the D99% of HT plans were slightly higher than those of VMAT plans (t=4.476, 3.756, P 0.05) were found. The V10, V15, V20 and mean lung dose (MLD) to the total-lung of HT plans were all significantly lower than those of VMAT plans (t=-3.369,-4.824,-4.869,-3.657, P 0.05). The monitor units and delivery time of VMAT plans were significantly lower than those of HT plans (t=13.970, 7.982, P<0.05). Conclusions Both HT and VMAT are appropriate for esophageal cancer radiotherapy. HT significantly reduces the radiation dose of the total-lung, while VMAT has obvious advantages in efficiency. Key words: Esophageal neoplasms; Helical tomotherapy; Volume-modulated arc therapy; Dosimetry