Course book Advanced Treatment Planning 2018

Use of abutting beams

▪ Electron - electron beam matching

▪ difficult to match without hot- or cold-spots due to influence on isodose lines of patient curvature

▪ Electron – photon beam matching ▪ beams abutted on the surface gives a hot spot on the photon side and a cold spot on the electron side

electron

photon

▪ caused by out-scattering of electrons from the electron fields