Table 1.

Patient and scan characteristics.

	Mammography		HN CT
Number of scans	40		39
Number of ROIs	40		39
Peak kilovoltage (kVp)	24 ($n=1$)	29 ($n=19$)	120 ($n=32$)
	26 ($n=1$)	30 ($n=3$)	140 ($n=7$)
	27 ($n=2$)	31 ($n=8$)
	28 ($n=5$)	32 ($n=1$)
Slice thickness (mm)	NA		2.5 ($n=3$)
			3.0 ($n=36$)
Mean pixel spacing (range) (mm)	0.1 (0.1 to 0.1)		0.536
			(0.424 to 0.688)
Scanner manufacturer and model	GE Senographe 2000D		Philips brilliance 16 ($n=5$)
			Philips brilliance 64 ($n=30$) Philips iCT 256 ($n=3$)
			Siemens biograph 64 ($n=1$)