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Feasibility Study of Dynamic Arc and IMRT Treatment Plans Utilizing Vero Treatment Unit and IPlan Planning Computer for SRS/FSRT Brain Cancer Patients

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S Lee

S Huh , S Lee*, R Dagan , R Malyapa , N Mendenhall , W Mendenhall , M Ho , D Hough , M Yam , Z Li , UFPTI, Jacksonville, FL


SU-E-J-70 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose:To investigate the feasibility of utilizing Dynamic Arc (DA) and IMRT with 5mm MLC leaf of VERO treatment unit for SRS/FSRT brain cancer patients with non-invasive stereotactic treatments. The DA and IMRT plans using the VERO unit (BrainLab Inc, USA) are compared with cone-based planning and proton plans to evaluate their dosimetric advantages.

Methods:The Vero treatment has unique features like no rotational or translational movements of the table during treatments, Dynamic Arc/IMRT, tracking of IR markers, limitation of Ring rotation. Accuracies of the image fusions using CBCT, orthogonal x-rays, and CT are evaluated less than ~ 0.7mm with a custom-made target phantom with 18 hidden targets. 1mm margin is given to GTV to determine PTV for planning constraints considering all the uncertainties of planning computer and mechanical uncertainties of the treatment unit. Also, double-scattering proton plans with 6F to 9F beams and typical clinical parameters, multiple isocenter plans with 6 to 21 isocenters, and DA/IMRT plans are evaluated to investigate the dosimetric advantages of the DA/IMRT for complex shape of targets.

Results:3 Groups of the patients are divided: (1) Group A (complex target shape), CI’s are same for IMRT, and DGI of the proton plan are better by 9.5% than that of the IMRT, (2) Group B, CI of the DA plans (1.91+/-0.4) are better than cone-based plan, while DGI of the DA plan is 4.60+/-1.1 is better than cone-based plan (5.32+/-1.4), (3) Group C (small spherical targets), CI of the DA and cone-based plans are almost the same.

Conclusion:For small spherical targets, cone-based plans are superior to other 2 plans: DS proton and DA plans. For complex or irregular plans, dynamic and IMRT plans are comparable to cone-based and proton plans for complex targets.

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