Program Information
A Systematic Planning Quality Monitoring Program for VMAT Treatment
G Zeng1*, M Robertson2 , J Murphy3 , M Lamey4 , Y Wang5 , (1) Trillium Health Partners/the Credit Valley Hospita, Mississauga, ON, (2) Trillium Health Partners, Mississauga, Ontario, (3) Trillium Health Partners, Mississauga, Ontario, (4) Trillium Health Partners, Mississauga, Ontario, (5) Trillium Heath Partners, Mississauga, Ontario
Presentations
SU-D-201-2 (Sunday, July 31, 2016) 2:05 PM - 3:00 PM Room: 201
Purpose:To demonstrate a systematic tracking program for planning quality; to advocate that commercial treatment planning systems develop tools to monitor population-based quality in order to justify technology change in respect to clinical outcome.
Methods:The DVH (Dose Volume Histogram) files of VMAT patients since 2011 have been exported from Varian Eclipse treatment planning system. The nomenclature of structures has been standardized and the planning process has been semi-automated for clinical sites where such efforts bring clinical and operational benefits, such as GU. An in-house program was developed in C++ to extract the dose volume points of targets and organs at risk from the exported DVH files. The control points were determined by QUANTEC (Quantitative Analyses of Normal Tissue Effects in the Clinic) organ specific dose volume recommendations for toxicity control. Monitor units were used as the indication of treatment efficiency. Control charts for dose volume points and monitor units were created to monitor planning quality dynamically.
Results:The figures in the supporting document show some examples of prostate 78Gy plans over the most recent 30 months. The contoured CTV, rectum and bladder are statistically stable at 74±27 cm3, 77±28cm3 and 366±165cm3, respectively, reflecting consistence in target delineation, bowel and bladder preparation. Rectum V50, V60, V65, V70 and V75 remain at 24±6 %, 18±5%, 16±5%, 13±4 % and 9±4%, respectively, well below QUANTEC recommendations of 50%, 30%, 25%, 20% and 15%. The stability is also observed in targets and other OARs’ doses. However, monitor units have increased by 11%, from 533±42MU to 594±40MU, after Eclipse version 11 upgrade in which the optimization algorithm was changed.
Conclusion:Monitoring population-wise quality provides an assessment of technology changes and clinical outcomes, which can help guide future development. We therefore recommend these types of tools be incorporated in commercial treatment planning systems.
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