Program Information
A Plan Quality Comparison for Volumetric-Modulated Arc Therapy by Different Maximum Delivery Time Setting for Cervical and Upper Thoracic Esophageal Cancer
j Yang1 , D Liu2*,M Miao2 ,z Jing2 , Z Li2 (1) Cang zhou people's hospital, Cangzhou, Hebei, (2) The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei
Presentations
SU-E-P-53 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose:To evaluate and compare the treatment plan quality of volumetric modulated arc therapy (VMAT) plans using different constrain conditions of delivery time for cervical and upper thoracic esophageal cancer.
Methods:In this retrospective study, single-arc VMAT plans were generated with the Oncentra 4.3v system for twenty cervical and upper thoracic esophageal cancer cases. The maximum delivery time were set systematically various as 80s, 110s and 150s. Planning objectives were to deliver 60 Gy in 30 fractions to 95% of PTV, with maximum doses of spinal cord <45 Gy, V5Gy<50%, V10Gy<40%, V20Gy<25% and V30Gy<20% to the lung tissue. All of the three groups of VMAT plans were clinical acceptable. For plan evaluation statistics, PTVDmax, PTVDmin, PTVDmean, PTVD100~D2, PTVV110~V90, CordDmax, CordD2, CORDD40, LungDmean, LungV5~V40 were analyzed and compared by SPSS 20.0.
Results:The dose distribution quality of plans generated by different maximum delivery time settings was assessed by anova and non-parametric tests. No significant differences were found for target and OAR parameters except for the hight dose volume of PTV. The maximum dose (p = 0.034) and D2% (p = 0.030) of PTV in plans with 80s setting were detected significant lower than other plans by anova analysis. And for the maximum dose (p = 0.039) of PTV, it was showed the same results by non-parametric tests.
Conclusion:Considering of the quality of VMAT plans and the treatment time, 80s as the initial parameters of the maximum delivery time would be a better choice than 110s and 150s for cervical and upper esophageal cancer.
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