Advanced TP

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