Author: David L. Barbee, Paulina E. Galavis, Lena Adel Samad, Jose R. Teruel Antolin 👨🔬
Affiliation: NYU, NYU Langone Health 🌍
Purpose: To validate an automated script that converts treatment plans of varying Varian MLC models
Methods: A C# script was developed using the Eclipse Scripting API to convert treatment plans between different MLC models. The script functions in two distinct modes: (1) when the MLC apertures can be fully reproduced, the script recreates the fields and calculates a new plan; (2) when the MLC apertures cannot be fully reproduced, the script sets up and runs optimization and calculation processes, with objectives derived from the existing plan for the new MLC model. The script tested for conversion between the Varian Millennium MLC 120 and the Varian HD-MLC in both directions.
Ten previously treated patients (prostate and partial brain sites) were selected for testing. The converted plans were normalized to achieve the same target coverage as the original plans. Results were evaluated through gamma analysis of the final dose files using the PyDicom package and by delivering patient-specific QA plans with the ArcCheck phantom.
Results: The plan conversion process took an average of 2 minutes for converting Millennium MLC plans to HD-MLC, and 12 minutes for converting HD-MLC plans to Millennium MLC. Gamma comparison between original and converted plans yielded a passing rate over 90% for all cases using a gamma criteria of 5%/3mm (50%threshold). Patient-specific QA results were comparable between converted and original plans, consistently meeting our institution's criteria of >90% for a 3%/2mm (10% threshold) gamma criterion
Conclusion: The developed script provides a quick and clinically equivalent method for generating treatment plans. This makes it a valuable tool to prevent treatment delays or cancellations, ensuring continuity of care and alleviating the workload on dosimetrists.