Physics Bucharest 2017

Head and neck cancer (historic-conventional)

T2N2(a)M0 SCC of tonsil Issues to consider for matching

Post beam used to treat post neck nodes (9-12MeV) overlying the spinal cord (esp if prescribed dose i.e 55Gy in 25f to neck exceeds spinal cord tolerance) matched to beam (electron-photon) • Solutions • Match beams at 50% (light beam) isodose • =Match edges of 2 light beams on the surface of shell

High dose PTV extends post to spinal cord- - hot spot created by lat bowing of electron isodoses at depth and unavoidable matching close to GTV.