Table 3.

kVp, type of bowtie, and collimation variations used on each make and model of scanner to gather free-in-air CTDI measurements; axial scan mode and 1 s exposure times were used for all techniques. A total of 21, 12, and seven techniques were tested on each of the three GE VCT, GE LightSpeed 16, and Siemens Sensation 64 units, respectively.

Scanner make and model	kVp	mA s	No. of channels	Channel width (mm)	Bowtie
GE VCT	80, 100, 140	350	64	0.625	Small, medium, large
	120	350	8, 16, 32, 64	0.625	Small, medium, large
GE LightSpeed 16	80	350	16	1.25	Small, large
	100, 140	250	16	1.25	Small, large
	120	250	4, 8, 16	1.25	Small, large
Siemens Sensation 64	80, 100, 120, 140	350	24	1.2	Large
	120	350	32	0.6	Large
	120	350	1, 2	5	Large