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Example 4: Modelling the MLC in Eclipse by Varian
Eclipse Algorithms Reference Guide v13+
Transmission and Tongue & Groove effect
•
MLC Transmission parameter
accounts for both
inter- and intra- leaf transmission.
Fluence delivery modelling algorithms: programs to convert optimal fluence patterns to deliverable
fluence patterns, where the influence of the MLC is taken into account (Leaf Motion Calculator, LMC)
Leaf Ends
•
Leaf-end shape is modelled
flat
.
•
The dosimetric leaf gap (DLG) parameter
is a
configuration parameter used in the fluence delivery
models. It is used to shift the MLC leaf tip position
by half its value to account for the transmission
through the rounded leaf.
•
Initial estimates of the DLG & MLC Trans
parameters are measured by the user using a
set of dynamic MLC fields (sliding window
delivery patterns) defined by the vendor
•
There is no ray-tracing through leaf ends or
between leaves
Lo Sasso, Med. Phys., 25(10), 1998m 1919-1927
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