Table 2.

Coordinate systems used in the Elekta Unity system and in this article, compared to a head first supine (HFS) patient (see Fig. 1)

HFS Patient	IEC 61217 fixed	DICOM	MVI G0o	MVI G90o
Left	+x	+xDICOM	+u
Superior	+y	+zDICOM	‐v	‐v
Anterior	+z	‐yDICOM		‐u