Table 1. The target and PTV evaluation volume definitions for conventional and SIMBa VMAT planning.

VMAT: volumetric modulated arc therapy; SIMBa: simultaneous integrated marrow and body approach; PTV: planning target volume; AP: anterior-posterior; PA: posterior-anterior

	Target definition – Conventional VMAT TBI	Target definition – SIMBa
Body	Automatically generated External contour
PTV_BodyEval	Automatically generated External contour (Body) with a 5mm uniform retraction away from skin minus the lung volume and any optional OARs
PTV_Upper	The portion of the PTV_BodyEval that encompassed the VMAT arc isocenters (Head, Chest, Abdomen and Pelvis)
PTV_Lower	The portion of the PTV_BodyEval that encompassed the field-in-field AP/PA technique isocenters (Upper Leg and Lower Leg).
PTV_Marrow	-	Contoured skeletal system
PTV_TotalBody	-	PTV_BodyEval minus the PTV_Marrow