Redefining plan quality in head-and-neck VMAT via RayStation MCO versus standard optimization: A dual analysis of dosimetry and delivery accuracy.

To determine whether multicriteria optimization (MCO) improves volumetric-modulated arc therapy (VMAT) plans for head-and-neck cancer compared with standard optimization in terms of dosimetry, treatment efficiency, and patient-specific quality assurance (QA). Ten clinically treated patients with oropharyngeal carcinoma each received 2 dual-arc 6-MV VMAT plans in RayStation v8A: one standard optimization plan and one MCO plan. Dose-volume endpoints included D98%, D50%, D2%, homogeneity index, and conformity index for each planning target volume, as well as mean or maximum doses to 23 organs at risk. Efficiency was assessed by total monitor units and delivery time. Pretreatment QA was performed using the OCTAVIUS-4D system, with global and local gamma passing rates (3%/3 mm and 3%/2 mm, 10% threshold) recorded. Computed tomography was used only for routine setup verification and repositioning. Paired data were analyzed using the Wilcoxon signed-rank test (α = 0.05). MCO significantly enhanced target coverage and uniformity (e.g., planning target volume-70: D98% + 1.3 Gy; homogeneity index 0.04 ± 0.01 vs 0.09 ± 0.02; conformity index 0.98 ± 0.02 vs 0.85 ± 0.04; all p ≤ 0.005). Mean parotid dose fell by 2.5 Gy and spinal cord D0.01cc by 1.4 Gy (p ≤ 0.005). MCO lowered monitor units by 19% (579 ± 127 vs 714 ± 170; p = 0.017) and reduced delivery time. All plans exceeded a 95% gamma passing rate, MCO showed marginally higher agreement under both global and local normalization (p < 0.01). MCO in RayStation yields more homogeneous and conformal VMAT plans, better spares critical structures, and increases delivery efficiency while maintaining excellent QA metrics. These advantages support its routine clinical adoption for complex head-and-neck radiotherapy cases.