PMID- 28341061 OWN - NLM STAT- MEDLINE DCOM- 20171003 LR - 20181202 IS - 1879-0887 (Electronic) IS - 0167-8140 (Linking) VI - 123 IP - 1 DP - 2017 Apr TI - VMAT plus a few computer-optimized non-coplanar IMRT beams (VMAT+) tested for liver SBRT. PG - 49-56 LID - S0167-8140(17)30095-6 [pii] LID - 10.1016/j.radonc.2017.02.018 [doi] AB - PURPOSE: To propose a novel treatment approach, designated VMAT+, involving addition of <5 IMRT beams with computer-optimized non-coplanar orientations to VMAT, and evaluate it for liver Stereotactic Body Radiation Therapy (SBRT). VMAT+ is investigated as an alternative for (1) coplanar VMAT and (2) multi-beam non-coplanar treatment. METHODS/MATERIALS: For fifteen patients with liver metastases, VMAT+ plans were compared with (1) dual-arc VMAT and (2) 25-beam, non-coplanar treatment with computer-optimized beam orientations (25-NCP). All plans were generated fully automatically for delivery of the highest feasible tumor Biologically Effective Dose (BED). OAR doses, intermediate-dose-spillage, dose-compactness, and measured delivery times were evaluated. RESULTS: With VMAT+ the maximum achievable tumor BED was equal to that of 25-NCP. Conversely, VMAT resulted in a lower tumor BED in 5 patients. Compared to VMAT, VMAT+ yielded significant dose reductions in OARs. Intermediate-dose-spillage and dose-compactness were significantly improved by 9.8% and 17.3% (p