Table 2.

Summary of various published recommendations for margins around target volumes (CTV)

Author	Region	Recipe
Stroom et al.(1999a) [26]	PTV	2∑ + 0.7σ
Van Herk et al.(2000) [27]	PTV	2.5∑ + 0.7σ
Parker et al. (2002) [28]	PTV	$\sum +\sqrt{({\sigma }^2+{\sum }^2)}$
Snoke JJ (2007)	PTV	2.5∑ + β(σ 2 + σ 2P)1/2 − βσ P

Symbols: ∑, standard deviation of systematic uncertainties; σ, standard deviation of statistical (random) uncertainties. σ _P =0.64, β =0.84.