A Novel Integrated VMAT/IMRT Technique for the Treatment of Non-Small Cell Lung Cancer: Novel Therapies/Experimental Therapies

Abstract

To investigate a novel Integrated VMAT/IMRT technique which combines volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) for non-small cell lung cancer (NSCLC). Two partial arcs VMAT, 5-field IMRT and Integrated VMAT/IMRT plans were created for 17 patients with NSCLC. The Integrated VMAT/IMRT technique consisted of 2 partial VMAT arcs and 5 IMRT fields. The dose distribution of planning target volume (PTV) and organs at risk (OARs) for Integrated VMAT/IMRT was compared with IMRT and VMAT. The monitor units (MUs) and treatment delivery time were also evaluated. For each plan, a dry run was performed to assess the dosimetric accuracy. Integrated VMAT/IMRT significantly improved the target conformity and homogeneity. The V30 of normal lung for Integrated plans was significantly lower than IMRT plans (8.4% vs 9.2%; P<.05). The V5 and mean lung dose (MLD) of normal lung for Integrated plans were 9.8% and 4.6% lower than VMAT plans (P<.05). The maximum dose of spinal cord for Integrated plans was 4.9 Gy lower than IMRT plans (P<.05). The mean delivery time of IMRT, VMAT and Integrated plans was 280 s, 114 s, and 327 s, respectively. The mean MUs needed for IMRT, VMAT, and Integrated plans were 933, 512, and 737, respectively. The gamma pass rates were beyond 90% at the 3%/3 mm criteria when the gantry angles were set to 0° for pretreatment verification. Integrated VMAT/IMRT technique significantly reduced V5, V10, and MLD of normal lung compared with VMAT, and the irradiated volume of the OARs receiving medium to high dose with fewer MUs compared with IMRT. Integrated VMAT/IMRT technique can be a feasible radiation therapy technique with better plan quality and accurately delivered on the linear accelerator.Thoracic Abstract 217; TableDosimetric comparison of PTV and OARs for IMRT, VMAT, and Integrated VMAT/IMRT plansIMRTmean±SDVMATmean±SDIntegratedmean±SDIMRT vs VMATP valueIMRTvs IntegratedP valueVMATvs IntegratedP valuePTV CN0.7±0.10.8±0.10.9±0.1<.05<.05<.05 HI (%)16.1±3.613.9±3.49.9±1.4<.05<.05<.05Normal lung V30 (%)9.2±4.28.9±4.98.4±4.4>.05<.05>.05 V10 (%)21.5±10.324.9±12.323.5±11.8<.05<.05<.05 V5 (%)34.1±15.842.9±19.138.7±18.1<.05<.05<.05 Mean (Gy)8.1±3.38.7±3.78.3±3.5<.05<.05<.05Spinal cord Dmax (Gy)36.4±13.430.6±10.431.5±10.4<.05<.05>.05Esophagus Dmax (Gy)51.2±16.151.8±14.950.6±13.9>.05>.05<.05 Mean (Gy)14.0±10.315.2±9.814.6±9.8<.05>.05<.05 Open table in a new tab