ESTRO course Dose Modelling and Verification 2017

Modelling the MLC - 2

Philips Pinnacle

Physics Reference Guide v9.10

Typical values

Leaf-end curvature: 8 – 15 cm

MLC leaf offset: 0.1cm

Tongue & groove width: 0.1cm

MLC intra-transmission: 1.5-2%, interleaf trans: 5%

Williams et al PMB, 51 (2006) N65-N78

Young et al, J App Clin Med Phys, 17(6), 2016

•MLC leaf ends are modelled rounded

•No explicit ray-tracing through leaf ends

•The difference between nominal leaf end and radiation field (one HVL of beam attenuation) is

approximated by an off-set parameter and the leaf end curvature (‘leaf off-set table’)

•T&G modelled using an adjustable parameter (no ray tracing)