Table 2: Summary of imaging settings and whole body doses over a typical 37 fraction treatment course measured on the Clinac iX machines. TrueBeam imaging dose parameters are included, however CTDI phantom measurements were not obtained. Instead air kerma measurements were taken for each imaging protocol on both Clinac and TrueBeam machines and a further dose reduction of 50% for TrueBeam is inferred from these results (see Table 3).

Group	kV	mA	mS	mAs	CTDIw100	Dose (cGy)	Dose diff (%)	Dose (37#) (Gy)
					(mGy/mAs)
Clinac iX Imaging Parameters
Spotlight	125	80	25	704	4.09	2.9	0	1.1
Pelvis S	100	40	12	609	1.59	0.5	−83.2	0.2
Pelvis M	100	63	20	1014	1.57	1.3	−56.5	0.5
Pelvis L	110	80	20	1013	2.3	2.3	−19.2	0.9
Pelvis XL	125	80	25	1266	3.17	4	39.4	1.5
TrueBeam Imaging Parameters
Pelvis S	100	40	12	317
Pelvis M	100	63	20	832
Pelvis L	125	80	16	845
Pelvis XL	125	80	25	1320

CTDI, CT dose index.