Physics Bucharest 2017
6/3/2017
MU efficiency and leakage
Exposure outside beam aperture
MV beam
Jaws
Head/Jaw leakage 0.1% MLC leakage 0.5% to 3%
MLC leaf
Zone I: Primary beam “ Wanted dose” to target “ Unwanted dose” to healthy tissue and OAR in the beam path Zone II: MLC/Collimator Leakage + scatter “ Unwanted dose” Zone III: Linac head leakage + scatter “ Unwanted dose”
Zone I Zone II Zone II Zone III
Zone III
75
ESTRO physics course 2017
MU efficiency and leakage
MV beam
MV beam
Jaws
Jaws
MLC leaf
MLC leaf
Open beam: 140 MU
Sliding window (1 cm): 680 MU
76
Remark: For this particular MLC device average leakage < 1% ESTRO physics course 2017
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