Program Information
An Analysis of VMAT SBRT Lung Treatment Plans
D Wilson*, J James , B Wang , N Dunlap , S Woo , C Silverman , A Dragun , M El-Ghamry , Univ Louisville, Louisville, KY
Presentations
SU-E-T-96 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose:To present an analysis of 218 lung sbrt treatment plans delivered using Varian Eclipse RapidArc software and delivered with Varian linear accelerators.
Methods:A retrospective analysis of treatment plans generated using the Varian Eclipse PRO RapidArc VMAT optimization and AAA photon beam calculation algorithms was done for 218 plans delivered using Varian Trilogy and TrueBeam linear accelerators. Some of the patients were enrolled in the RTOG 0813 and RTOG 0915 lung protocols. All of the patients’ plans were optimized using the guidelines outlined by these protocols. The plans presented were normalized so that 95% of the PTV volume received 100% of the prescribed dose.
Results:The dose co formality constraints from the RTOG protocols and the number of plans within those constraints were:
Tumor dose between 60% of maximum dose and 90% of maximum: 218/218 = 100%.
Volume of 105% tumor dose outside put less than 15% of the PTV volume: 218/218 = 100%.
Maximum dose 2 cm away from PTV within protocol table guidelines: No minor deviation: 188/218 = 86.2%. No major deviation: 216/218 = 99.1%.
Ratio of 50% dose volume to PTV volume less than R50 in protocol table: No minor deviation 148/218 = 67.9%. No major deviation: 213/218 = 97.7%.
Percent of lung receiving 20 Gy less than 10% (no minor violation): 218/218 = 100%.
99% of PTV receiving at least 90% of the tumor dose: 214/218 = 98.2%.
Conclusion:Varian RapidArc VMAT can successfully deliver lung SBRT treatments as outlined in the RTOG 0813 and 0915 protocols. The largest deviations were seen in the R50 constraints for the larger PTV volumes.
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