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A Dosimetric Comparison of Two Different Optimization Modes Used in Monaco Treatment Planning System During VMAT for Lung Cancer

S Chinnadaikkan1*, M Palanisamy1 , T Thangaraj1 , N Bhalla1 , A Puri1 , (1) Fortis Hospital, Department of Radiation oncology, Mohali, Punjab, India


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: This study compared two different optimization modes used in Monacoâ„¢ treatment planning system (TPS) during volumetric modulated arc therapy (VMAT) for lung cancer.

Methods: For this study, five lung cancer patients treated with 60Gy/30 fractions were chosen from a clinical database. Plans were generated using VMAT technique in Monacoâ„¢ V5.1 TPS for Elekta Synergyâ„¢ linear accelerator with 1 cm leaf width at the isocenter. VMAT plans were generated using 6MV photon beam energy with partial arcs. The reference plan was generated using Constrain optimization mode (COM), where the priority is given to normal tissue during optimization. By keeping all other parameters as constant in the reference plan, only by changing optimization into Pareto mode, plans were generated. For plan comparison, conformality index (CI), homogeneity index (HI), dose coverage to the planning target volume (PTV), mean dose, max dose and dose volume received by organ at risk (OAR) for heart, right lung, left lung, spinal cord were analyzed. In addition, normal tissue integral dose (NTID) to normal tissue (liter-gray), total monitor unit (MU) and delivery time (mins) was analyzed.

Results: The CI and HI improved in POM as compared to COM value (p>0.05). The mean dose, max dose and dose received by 95% volume to PTV were slightly increased in POM as compared to COM (p>0.05). The mean dose and dose volume received by the heart, spinal cord, right lung ,left lung and NTID showed a slightly lesser dose in COM as compared to POM (p>0.05). A slight increase of MU and delivery time was observed in COM as compared to POM (p>0.05). Overall, both optimization modes showed the insignificant difference in plan quality (p>0.05).

Conclusion: For lung cancer, during VMAT plan optimization, one can use any of the two optimization modes according to clinical need without compromising plan quality.


Not Applicable / None Entered.


TH- External beam- photons: treatment planning/virtual clinical studies

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