Physics Athens 2016

MU efficiency and leakage

Exposure outside beam aperture

MV beam

Jaws

Head/Jaw leakage 0.1% MLC leakage 1% 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” Related to beam-on time (#MU)

Zone I Zone II Zone II Zone III Zone III