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 IJMPCERO  Vol.6 No.2 , May 2017
A Radiotherapy Treatment Margin Formula When Systematic Positioning Errors are Relatively Small Compared to Random Positioning Errors: A First-Order Approximation
Abstract: A radiotherapy treatment margin formula has been analytically derived when a standard deviation (SD) of systematic positioning errors Ʃ is relatively small compared to an SD of random positioning errors σ. The margin formula for 0 Ʃ σ was calculated by linearly interpolating two boundaries at Ʃ = 0 and Ʃ = σ, assuming that the van Herk margin approximation of k1Ʃ + k2σ is valid at Ʃ = σ. It was shown that a margin formula for 0 Ʃ σ may be approximated by k1σ + k2Ʃ, leading to a more general form of k1 max(Ʃ,σ) + k2 min(Ʃ,σ) which is a piecewise linear approximation for any values of Ʃ and σ.
Cite this paper: Yoda, K. (2017) A Radiotherapy Treatment Margin Formula When Systematic Positioning Errors are Relatively Small Compared to Random Positioning Errors: A First-Order Approximation. International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 6, 193-196. doi: 10.4236/ijmpcero.2017.62017.
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