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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.