(Sunday, 7/29/2018) 3:00 PM - 6:00 PM
Room: Exhibit Hall
Purpose: To discuss the dosimetry differences between the planning methods of physical optimization and biological optimization in hypofractionated radiotherapy for lung cancer.
Methods: Ten cases of NSCLC lung cancer patients having received radiotherapy were selected for this retrospective study. New VMAT plans for these 10 cases were respectively designed with physical functions(DV group), biological-physical functions combination(DV+EUD group and EUD+DV group) and biological functions(EUD group), with different constrained functions but the same constrained conditions and optimized parameters. The dosimetric differences of the four optimization methods in hypofractionated radiotherapy of lung cancer were evaluated through calculating and analyzing dosimetry parameters.
Results: For the target area, equivalent uniform dose of the EUD group and the EUD+DV group are approximate. The EUD of the two groups is about 2.8%~3.6% and 3.2%~3.7% higher than those of the DV group and DV+EUD group, respectively. The average TCP of the EUD group and the EUD+DV group is also higher than those of the other two groups, and the difference is significant(P<0.05). The difference of HI between the three groups is also statistically significant(P<0.05) while the difference of CI is not statistically significant(P>0.05). For the OAR area, the difference of EUD,V5,V10,V20,V30 of normal lung tissues and difference dosimetry parameters of heart and spinal cord are not statistically significant(P>0.05).But the mean dose of all lungs of the EUD group and EUD+DV group are slightly lower than those of the other two groups.
Conclusion: There are obvious advantages of biological optimization method by increasing EUD and TCP, and decreasing the irradiation dose of normal lung tissue. This result is helpful to select optimization method with biological functions in clinical work.
Funding Support, Disclosures, and Conflict of Interest: The work is supported by the Innovation Research Project titled"Multi-modal image guided precision radiotherapy for non-small cell lung cancer "
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