Assessing the feasibility of uTPS for volumetric modulated arc therapy treatment plan optimization of dual-layer multileaf collimator linear accelerators

Dual-layer multileaf collimator (MLC) accelerators, such as Halcyon, are increasingly used in clinical settings; however, the ability of treatment planning systems (TPS) to effectively optimize treatment plans for such accelerators remains an important consideration. This study evaluates the feasibility of using uTPS to optimize treatment plans for dual-layer MLC accelerators, with Eclipse as a clinical reference. Standard radiation data from the Halcyon 2.0 accelerator were used to model the beam in the uTPS (Shanghai United Imaging Healthcare Co., Ltd., version R001). Twenty cases were selected, with five each for hypopharyngeal, esophageal, breast, and cervical cancers. Volumetric modulated arc therapy plans were generated using the uTPS stochastic platform optimizer and the Eclipse photon optimizer (PO). All plans were calculated using the Acuros external beam (AXB) algorithm for dosimetric comparison. Key indicators, such as the conformity index (CI), homogeneity index (HI), and organ-at-risk (OAR) doses, were analyzed and compared. The feasibility of delivering uTPS plans on the Halcyon accelerator was validated. The dosimetric accuracy was confirmed using ArcCheck, and Wilcoxon signed-rank tests with Benjamini–Hochberg false discovery rate correction were performed. uTPS and Eclipse plans exhibited similar dosimetric qualities for esophageal and cervical cancer cases, with no significant differences in CI, HI, and OAR doses. However, uTPS demonstrated superior OAR sparing in specific cases: in hypopharyngeal cancer, uTPS significantly reduced the brainstem \(\:{D}0.1cc\) by 34.48%, the left parotid \(\:\:{D}ₘₑₐₙ\) by 11.8%, and the left parotid \(\:{V}30Gy\) by 6.9% (all P < 0.05); in breast cancer, uTPS significantly reduced the spinal cord \(\:{D}0.1cc\:\) by 49.6% ( P < 0.05). No statistically significant differences were observed in other dosimetric parameters. No significant differences in total monitor units were observed between the uTPS and Eclipse plans. All uTPS plans were successfully delivered on the Halcyon accelerator, with gamma passing rates exceeding 97%. The commercially available uTPS supports effective plan optimization for dual-layer MLC Halcyon accelerators, offering plan quality comparable to that of Eclipse.