A Radiotherapy Treatment Margin Formula When Systematic Positioning Errors are Relatively Small Compared to Random Positioning Errors: A First-Order Approximation

• 作者: Kiyoshi Yoda
• 来源期刊: 医学物理学、临床工程、放射肿瘤学(英文)
• 学科: 数学
• 关键词: TREATMENT MARGIN Systematic POSITIONING ERRORS RANDOM POSITIONING ERRORS
• 年，卷（期）: 2017,（2）
• 页码范围: 193-196
• 页数: 4页
• 分类号: O1

摘要

A radiotherapy treatment margin formula has been analytically derived when a standard deviation (SD) of systematic positioning errors Ʃis relatively small compared to an SD of random positioning errors σ. The margin formula for 0 ≤ Ʃ≤ σwas calculated by linearly interpolating two boundaries at Ʃ= 0 and Ʃ= σ, assuming that the van Herk margin approximation of k1Ʃ+ k2σis valid at Ʃ= σ. It was shown that a margin formula for 0 ≤ Ʃ≤ σmay 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 Ʃand σ.