Table 2.

Advocated safety margins

Team	Metastases	Recommendation
Schefter et al. 2005 [20]	SBRT of liver metastases	Minimum distance between GTV and PTV surfaces:
		— 0.5 cm, axial planes
		— 1.0 cm, superior/inferior
		Cumulative maximum tumourdiameter: < 6 cm
Katria et al. 2010 [21]	IGRT of abdomen and pelvis	Stroom's and Van Herk's margins (cm):
		— 0.39 and 0.35 mm, anterior-posterior
		— 0.94 and 0.46 mm, medial-lateral
		— 0.40 and 1.09 mm, superior-inferior
Wysocka et al. 2010 [22]		Median 3.8 mm intrafraction craniocaudal displacement for coeliac axis with smaller displacements for other axes
RTOG consensus guidelines [23]	Inguinal lymph nodes	Caudad extent of the inguinal region : 2 cm to the saphenous/femoral junction
Kim et al. 2011 [24]	Inguinal and femoral nodes	2.2 - 2.9 cm around femoral vessels
Van Weieringen et al. 2011 [25]	Pelvic lymph nodes	For offline and online correction protocols, respectively:
		— 7 and 5 mm, left-right
		— 6 and 5 mm,craniocaudal
		— 8 and 7 mm,dorsoventral

RTOG: Radiation Therapy Oncology Group.