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Modelling the MLC - 4
Varian Eclipse,
Eclipse Algorithms Reference Guide v13+
Lo Sasso, Med. Phys., 25(10), 1998m 1919-1927
Parameters in beam model configuration
• Dosimetric Leaf Gap (or separation, DLG or DLS)
• Transmission through MLC leaves
• DLG: represents the additional gap width needed to reflect
the transmission through the rounded MLC leaf end
• MLC Transmission: includes inter and intra-leaf
transmission
These parameters are measured by the user using a set of
dynamic MLC fields (sliding window delivery patterns) defined
by the vendor
•MLC leaf ends are modelled straight (flat)
•No ray-tracing through leaf ends
•DLG & MLC transmission are measured parameters
serving as ‘first guess’ of the adjustable parameters
needed per beam