Abstract
INTRODUCTION: This study aimed to comprehensively analyze the dosimetric parameters, plan complexity, gamma passing rates (GPRs), and most importantly, the beam-on time (BOT) of stereotactic body radiotherapy (SBRT) for small-volume inoperable early-stage centrally-located non-small-cell lung cancer (NSCLC) at a radiotherapy center. The analysis was based on both single-arc (SA) and dual-arc (DA) VMAT techniques under the deep inspiration breath hold (DIBH) scenario. METHODS: We retrospectively selected 24 cases of small-volume inoperable early-stage centrally-located NSCLC treated with SBRT under the DIBH scenario at our institution between March 2021 and June 2024. The redesigned SA-VMAT plans (SA plans) adopted the same prescription dose of 50 Gy/5 fractions and flattening-filter free (FFF) beam as the original DA-VMAT plans (DA plans). The 2-group plans (i.e., the SA and DA plans) were normalized to cover 95% of the planning target volume (PTV) and 99% of the gross tumor volume (GTV) by the prescription dose. The evaluation factors included PTV parameters (D(98%), D(2%), HI, CI, and R(50%)), organs at risk (OARs), plan complexity (segments and MUs), GPRs, and BOT. RESULTS: The SA technique consistently yielded superior plans. Among the PTV parameters, the SA plans were superior to the DA plans in D(98%), D(2%), and HI (all p < 0.05), whereas the CI and R(50%) of the 2-group plans were comparable (all p > 0.05), and the SA plans had an increase in the ipsilateral PBT D(max) (p < 0.05). Otherwise, the differences between other OARs were insignificant (all p > 0.05). The SA plans had reduced complexity, with mean segments and mean MUs decreasing by 18.82% and 8.15%, respectively (all p < 0.001); the GPRs did not differ significantly under the three acquisition parameters (all p > 0.05). The mean BOT was reduced by 19.70% in SA plans (p < 0.001). DISCUSSION: The SA plans significantly shortened the BOT while maintaining comparable plan quality, thereby improving comfort for patients with small-volume inoperable early-stage centrally located NSCLC under the DIBH scenario. Future studies should accumulate more patient data to evaluate the long-term clinical outcomes of SA plans.