Table II.

Average, standard deviations, and ranges of mean CT numbers (HU) of sets of reference nodules scanned in water in an RMI QC phantom on a GE LightSpeed VCT CT scanner. Results are for 30 nodules (five 4.8 mm–50 mg/cc, five 4.8 mm–100 mg/cc, etc.), which were each scanned three times. (120 kVp, 320 mAs, 0.53:1 pitch, 0.625 mm slice, 0.3 mm slice interval for 4.8 mm nodules, 0.625 mm slice interval for others, 25 cm FOV).

Concentration		4.8 mm nodules	9.5 mm nodules	16 mm nodules
50 mg/cc	Minimum mean CT no.	53.1	61.5	59.4
	Maximum Mean CT no.	58.0	64.5	60.1
	Range (max-min)	4.8	3.0	0.8
	Average mean CT no.	56.0	63.1	59.7
	Standard deviation	2.0	1.3	0.3
100 mg/cc	Minimum mean CT no.	102.3	111.9	112.0
	Maximum mean CT no.	108.9	113.4	112.3
	Range (max-min)	6.7	1.6	0.4
	Average mean CT no.	104.7	112.5	112.2
	Standard deviation	2.7	0.6	0.2