Positioning and Stability Evaluation of the Model 2 NeoVista Brachytherapy System

Abstract

Abstract: : Purpose: To evaluate the positioning and stability of the NeoVista Brachytherapy system (model 2) to ensure accurate delivery of prescribed radiation in a simulated environment. Methods: Using an eye model to simulate the operative environment, three retinal surgeons used the Neo Vista Brachytherapy system (Model 2) to perform two procedures each. The surgeons held the device in the treatment position for the duration of the treatment. A detector output signal connected to a PC and a data acquisition software supplied information on the stability of the probe position vs. time. The results from all three surgeons were averaged to obtain the maximum and minimum mean dose rate within 2.5 mm circle (treatment area) on the detector output. The results were compared to the baseline testing results normalized to the proposed treatment dose of 26Gy. Results: The percentage Standard Deviation for accuracy and stability of Device Positioning is +/– 6.2 % or +/– 1.8 Gy (Range, 24.6 – 29.2 Gy). Considering a mean treatment dose of 26Gy and a variance of +/– 2*Standard deviation (95% confidence), this results in a dose range of 22.4–29.6Gy. Conclusions: The NeoVista Brachytherapy System Model–2 positioning and stability is adequate enough to ensure accurate delivery of prescribed radiation in a simulated use environment.

Keywords: age-related macular degeneration • choroid: neovascularization • radiation therapy