Rayline method

This is the earliest (and simplest) form of dose calculation. Electrons are assumed to travel along ray-lines originating from a single 'virtual' source. An appropriate shift of the percentage depth dose curve along these ray-lines accounts for the effect of tissue inhomogeneities. Dose distribution calculated in this manner does not reflect the lateral scattering of electrons near the edge of inhomogeneities or near-surface irregularities. Since these effects can lead to considerable dose perturbations, the ray-line method has been largely supplanted by the pencil beam method.

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