Establishing Systemwide SRT Transferability between Heterogeneous Mlc and Rtp Systems.
Abstract
Purpose
To develop and validate a methodology for assessing SRT patient transferability from an HD MLC LINAC with the BrianLab treatment planning system (TPS) to a standard Millenium MLC (SM MLC) LINAC planned with Eclipse TPS, with the goal of enabling systemwide implementation within a multi-site institution.
Methods
MLC output factors (OF) of the SM MLC were measured for field sizes, 1x1, 2x2, 3x3, 4x4, and 10x10 cm2, and compared with Eclipse TPS calculations. Dynamic conformal arc (DCA) plans for the evaluated field sizes were generated in Eclipse for both HD MLC and SM MLC configurations, and resulting dose distributions were compared using gamma analyses. A similar analysis was performed for spherical targets of diameters: 1-5 cm. Additionally, five clinical SRT cases (PTV volumes: 0.6 – 17 cc) were planned using Brainlab for HD MLC delivery and replanned in Eclipse for the SM MLC machine, with corresponding dose distributions compared using Gamma analysis. For patient-specific QA of the SM MLC system, the portal dosimetry (PD) results were compared against those of an SRS MapCHECK (PTV volumes: 0.3-19 cc).
Results
Eclipse-calculated OFs for SM MLC agreed with measurement within 0.75% for field sizes ≥3x3 cm2. Gamma passing rates for DCA plans comparing HD MLC and SM MLC exceeded 97% for field sizes ≥3x3 cm2, and exceeded 93% for PTV diameters ≥3cm. Dose distributions from Brainlab for the HD MLC and Eclipse for SM MLC demonstrated Gamma > 99% across all evaluated PTV sizes. PD results showed strong agreement with SRS MapCHECK measurements.
Conclusion
A robust methodology for transferring SRT patients between Brainlab-planned HD MLC and Eclipse-planned SM MLC platforms were developed and validated. This framework establishes a foundation for standardizing SRT planning and delivery across heterogeneous LINAC and RTP environments and will be expanded to enterprise-level implementation within a multi-site network.