A study on clinical evaluation of generalized equivalent uniform dose (gEUD) photon optimizer based VMAT planning on...

This study investigates the clinical performance and efficacy of generalized Equivalent Uniform Dose (gEUD) objectives in Volumetric Modulated Arc Therapy (VMAT) planning for Head and Neck Cancer (HNC) using the Halcyon LINAC Photon Optimizer (PO) engine.

50 HNC patients previously treated with Dose Volume (DV) based Halcyon VMAT plans were retrospectively selected. gEUD based plans were generated by re-planning the DV plans using gEUD objectives for organs at risk (OARs) and a combination of gEUD and DV objectives for PTVs, while maintaining consistent beam geometry and other optimization parameters. Target coverage (D95%, D98%, Dmean, D2%, V105%, CI, HI), OAR doses (mean and maximum), and treatment delivery parameters (MU, MF, BOT, PD gamma pass rate) were compared between the 2 planning strategies. A 2-tailed paired Student's t-test was used for statistical analysis, and box-and-whisker plots were generated.

The gEUD based planning achieved comparable PTV coverage and homogeneity to DV based planning. Critically, gEUD optimization significantly reduced mean parotid doses (p < 0.05). Substantial reductions in spinal cord and mandible doses were also observed with gEUD planning (p < 0.001). While small increases in brain dose were noted with gEUD, they remained below clinical tolerance limits. No significant differences were found in treatment delivery parameters or PD QA pass rates.

The gEUD based VMAT planning for HNC using the Halcyon LINAC demonstrates significant OAR sparing, particularly for parotids, spinal cord, and mandible, without compromising target coverage or delivery efficiency. These findings support the clinical implementation of gEUD optimization for HNC to potentially reduce treatment-related toxicity and improve the therapeutic window.