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Advantages of Multi-Criteria Optimisation in Volumetric Modulated Arc Radiotherapy Treatment Planning for Pancreatic Cancer

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A Johnston

A Johnston*, R Valentine, NHS Greater Glasgow and Clyde


SU-I-GPD-T-329 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To investigate whether multi-criteria optimisation (MCO) can produce superior treatment plans, in terms of reduction in dose to organs at risk and/or improved planning target volume coverage, for VMAT radiotherapy treatment of pancreatic cancers.

Methods: A retrospective planning study was carried out for ten pancreas patients, previously treated with VMAT radiotherapy. Each patient treatment was re-planned using a pre clinical release of an MCO tool within the Eclipse Treatment Planning System [Varian Medical Systems]. The resulting plan was compared to a plan optimised by the departmental lead in pancreatic planning. Differences in dose volume histogram parameters were reviewed for assessment of plan quality. Significance was assessed by two-tailed t-test (p<0.01). A visual assessment of the dose distribution was conducted and the number of MU was recorded for each plan.

Results: In comparing the MCO plans to the clinical plans, significant reductions were observed in the ipsilateral kidney V20Gy (mean: 14.6 percentage points; range: 3.5 - 24.0 percentage points), and in the spinal cord D0.1cc (mean: 8.4 Gy; range: 3.6 Gy - 11.9 Gy). The difference in contralateral kidney V5Gy and in liver V30Gy was not significant between the two plan sets. The difference in Dmin, D99% and D95% to PTV was not found to be significant as a result of implementing MCO. However the Dmean, Dmax and D2% to the PTV were all found to increase with significance. It was noted that the D2% did not breach the optimal clinical constraint in any of the ten cases and the highest recorded Dmax was 107.3% of prescription dose. On average, the number of MU increased for plans optimised using MCO. This difference was not significant.

Conclusion: Planning by way of MCO was shown to significantly decrease the dose to organs at risk without adverse affect on PTV coverage.

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