Fig. 3.
(a) System 1: accuracy of alignment of MV imager to the MV treatment beam isocentre for a period of 6 months; (b) system 2: accuracy of alignment of MV imager to the MV treatment beam isocentre for a period of 6 months; (c) system 2: accuracy of alignment of kV imager to the kV beam isocentre with reference to the MV beam isocentre for a period of 6 months.