Encrypted login | home

Program Information

IRIS/Cone and MLC-Based Pancreatic Treatment Plans for CyberKnife Sterotactic Body Radiotheraphy

no image available
D Michalski

D Michalski*, c Ozhasoglu , r Lalonde , d heron , M Huq , University of Pittsburgh Cancer Institute, Pittsburgh, PA


TH-EF-FS1-10 (Thursday, August 3, 2017) 1:00 PM - 3:00 PM Room: Four Seasons 1

Purpose: This study was to evaluate and compare dosimetric characteristics and efficiency of delivery of pancreatic cancer SBRT treatment courses of cone/Iris and MLC-based plans for CyberKnife M6.

Methods: This is a retrospective study of 35 pancreatic cancer patients. The mean age of the patients was 69.3 years,and the age range was 49-79. The mean PTV size was 22.3 cm3, and the range 7.83-53.98 cm3. Cone/IRIS and MLC-based CyberKnife treatment plans were generated on Multiplan 5.1.1. The target prescription isodose line was at 80% of the target maximum dose. The three-fraction prescription dose was 36 Gy. The comparison between plans' indices was determined with the non-parametric Wilcoxon signed rank test at the 0.05 significance level.

Results: The coverage is better for Iris plans. They had the mean coverage of 91.26%. The mean MLC plans coverage is 86.13%. Conformity index does not differ statistically for both plans with the mean CI for Iris 1.12 and 1.14 for MLC. There is a significant difference in monitor units between these plans, which also results in the difference in time delivery. For Iris plans the mean monitor units is 53947.17 and the mean delivery time is 97.46 min. For MLC plans the mean monitor units is 20951.97 and the mean delivery time is 49.94 min.

Conclusion: Optimization of the MLC plans was more challenging, especially with providing sparing of the bowel. Dosimetrically Iris plans are superior. The feasibility of the creation of SBRT pancreatic cancer plans for Iris/Cone and MLC CyberKnife was demonstrated. However from clinical perspective their delivery time can be viewed as prohibitive, particularly Iris plans. Only an extraordinary clinical scenario would warrant their administration.

Contact Email: