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Development of a Multi Criteria Optimization Framework for Dynamic Trajectory Radiotherapy

M K Fix*, F Daniel, W Volken, D Terribilini, D M Aebersold, P Manser, Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Switzerland


(Sunday, 7/29/2018) 3:00 PM - 6:00 PM

Room: Exhibit Hall

Purpose: Recently volumetric modulated arc therapy (VMAT) was extended by dynamic couch and collimator rotations resulting in dynamic trajectory radiotherapy (DTRT) improving treatment plan quality. In this work a multi criteria optimization (MCO) framework was developed for DTRT.

Methods: The approximation of the Pareto surface is based on individual DTRT optimizations leading to a set of database treatment plans. These plans are determined for given structures (target and organs at risk) by varying the values of their objective weights. Each DTRT optimization is performed using a research VMAT optimizer and the Eclipse Scripting Research Application Programming Interface (ESRAPI). The dose calculations resulting in deliverable dose distributions and dose volume histograms (DVHs) for the database treatment plans are used as input for navigation. For this purpose a dedicated navigation tool was developed, which displays dose distributions and DVHs and allows continuous navigation by interpolation. The MCO framework was applied for different clinically motivated cases. In order to validate the MCO framework the objective weights for navigated points were used to generate additional DTRT treatment plans. The deliverable dose distributions of these DTRT plans were compared with the interpolated dose distributions of the corresponding navigated points.

Results: The usage of the ESRAPI allows the automatic generation of the database treatment plans, which are then directly loaded by the navigation tool. For the cases studied the navigation showed the trade-off between tumor coverage and healthy tissue sparing. The interpolated dose distributions of navigated points showed good agreement with the deliverable dose distributions of the additional DTRT plans and thus validate the developed MCO framework.

Conclusion: An MCO framework was successfully developed for DTRT. The results demonstrate that navigation on the approximated Pareto surface allows determining a treatment plan considering patient specific situations. This work was supported by Varian Medical Systems.

Funding Support, Disclosures, and Conflict of Interest: This work was supported by Varian Medical Systems


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