(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: To compare and evaluate the quality of multi criteria optimization plans with Precision plan on comprehensive breast treatment and chest wall with involved lymph nodes.
Methods: Four cases of comprehensive breast plans and five chest wall with supraclavicular and axillary lymph nodes were selected for the study. Same field size and pitch. Pareto optimal plans were generated based on the objectives set. Slider were used to get an optimum plan. Further optimization was done to tweak the DVH. Homogeneity index is calculated as ratio of minimum dose in 5% of Planning Target volume to minimum dose to 95% of the PTV (D5/D95). Conformity index was calculated as the volume receiving 95% of prescription dose to the Planning tumor volume (PTV). The mean dose to the heart in both set of plan were kept equal. The MCO plans were normalized such that 95% of the PTV receives prescription dose. The quality of the plan were evaluated based on the conformity index, homogeneity Index and sparing of the critical structures. OAR were evaluated by V30 to ipsilateral lung, mean dose to lungs and Esophagus.
Results: All MCO plans achieved the required coverage of 95% of PTV receiving prescription dose while Precision plans had an average 98+1% coverage. The Ipsilateral Lung dose V20 is 14% less in MCO but the mean lung dose were the same. The esophagus has a 27% less mean dose in MCO than the Precision plan. Conformity Index was 7% higher in MCO while homogenity index was the same 1.08.
Conclusion: MCO plans are comparable to the Precision plans, although the critical structures received less dose the conformity of dose is better in Precision plans.
Keywords
Not Applicable / None Entered.
Taxonomy
TH- External beam- photons: treatment planning/virtual clinical studies
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