Room: AAPM ePoster Library
Purpose: Recently RayStation became the first third-party treatment planning system (TPS) to support the TomoTherapy treatment delivery system (TDS). At present, little guidance exists in the field for clinical use of this TPS and TDS pairing. This work describes an approach used to commission and validate the RayStation TPS for patient treatments using the TomoTherapy TDS.
Methods: A TomoTherapy beam model was created, focusing on achieving agreement between calculated and measured doses for simplified treatment plans spanning all delivery modes as delivered to a cylindrical phantom. The finalized model was then applied to create a set of nineteen validation treatment plans representative of the typical clinical utilization of the TDS. These plans were measured using ion chambers, film, and a calibrated Delta4+ to evaluate model accuracy. End-to-end testing and independent verification were performed using the IROC TomoTherapy phantom. Following clinical release, ongoing patient-specific QA results were monitored to evaluate model and machine performance.
Results: For the simplified commissioning plans, measured¬-to-calculated point dose ratios in the initial beam model averaged 1.019 (range 0.998-1.034) and improved to an average of 0.996 (range 0.984-1.011) in the final beam model. For validation plans, the average difference between ion chamber absolute point dose measurements and calculated values was 1%, sampled at various points within the treatment volumes. All film and Delta4+ measurements passed gamma analysis using institutional IMRT QA standards, and often with stricter criteria. IROC phantom end-to-end testing reported a ratio of measured-to-expected dose of 0.99. Of 162 patient plans measured and evaluated since clinical release, all have passed IMRT QA metrics with an average median dose deviation of -0.3% (range -2.3% to +2.6%).
Conclusion: The RayStation TPS can accurately model a TomoTherapy TDS and is suitable for clinical use in creating and delivering TomoTherapy treatment plans.