Encrypted login | home

Program Information

Comparing the Planned Dose Distributions in CyberKnife Treatments for Intracranial Tumors Between Ray-Tracing and Monte-Carlo Algorithms

W Jiang

W Jiang1*, S Sharma1 , Y Feng1 , B Tonner1 , (1) Department of Radiation Oncology, East Carolina University, Greenville, NC 27834


SU-I-GPD-T-601 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To compare the dose distributions calculated using the Ray-Tracing (RAT) and Monte Carlo (MC) algorithm for CyberKnife treatments of intracranial tumors and to evaluate the effects of the implementation of MC algorithm in intracranial tumor treatment planning.

Methods: Plans to treat four different positions (occipital, pituitary, cerebella, and right side of brain) of intracranial tumors were created using Multiplan 5.2.1 and RAT dose calculation. Total dose of 21 Gy to 30 Gy were prescribed in 3 to 5 fractions to the 73%-83% isodose line of the gross tumor volume plus a 2-mm/3-mm margin (GTV_m). For evaluation and comparison, the MC algorithm is used to recalculate the dose distribution for those plans using the same prescriptions, beams, beam directions, and monitor units(MUs).

Results: The percentage coverage of GTV_m calculated by the RAT is up to 7.9% higher than the MC plans (in the pituitary plan) when identical MU is used for both plans. The mean dose to GTV_m calculated by the RAT is up to 1.86% higher than the MC plans, but the maximum doses calculated by the RAT to GTV_m are all identical to the MC plans. The maximum doses of organs-at-risks (OAR) in RAT plans are on average 1.92% less than in MC plans.

Conclusion: The differences in target and OAR doses calculated from RAT to MC algorithm for intracranial tumors are not significant and most of their differences are within 2%. Special attention only need to be applied to the selection of planning algorithm for relatively smaller field planning based on tumor size and location especially when it’s adjacent to heterogeneous tissues such as pituitary, which is adjacent to the sinus cavities.

Contact Email: