Penumbra evaluation of the varian millennium and BrainLAB M3 multileaf collimators

Conclusions: The results of this study show a difference in the leaf penumbra parallel to the direction of leaf motion between two MLCs designed for precision radiation therapy. This difference may be attributed to the leaf tip design and is determined by the maximum field size of the MLC. This difference is currently not modeled by all treatment planning systems and should be taken into account as part of any procurement assessment of a system for precision radiation therapy in the same way that the width of the leaf at isocenter would be considered.