Measurement Techniques, Modeling Strategies and Pitfalls to Avoid when Implementing a Mini MLC in a Non Dedicated Planning System*

BACKGROUND AND PURPOSE: Ghent University Hospital investigated the feasibility of the Pinnacle system for planning intracranial stereotactic treatments. The aim was to perform precise dose computation using the collapsed cone engine for treatment delivery with the Moduleaf mini-MLC mounted on an Elekta accelerator. MATERIAL AND METHODS: The Moduleaf was commissioned using dose rate corrected data recorded by a diamond detector and using data measured by cylindrical chambers each limited to restricted field sizes. RESULTS: Automatic modeling resulted in clinical relevant dose errors up to 10%. Using manual modeling in Pinnacle, for clinical applicable fields a 2%/2 mm agreement between modeled data and measurements was obtained. CONCLUSION: The overall accuracy of the collapsed cone algorithm is within tolerances for single fraction stereotactic treatments.