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Use of abutting beams
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Electron - electron beam matching
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difficult to match without hot- or cold-spots due to
influence on isodose lines of patient curvature
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Electron – photon beam matching
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beams abutted on the surface
gives a hot spot on the photon
side and a cold spot on the
electron side
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caused by out-scattering of
electrons from the electron
fields
photon
electron