Table 9.

Results for DEQC Protocol 2. Technique parameters found to be major variance contributors for combinations of test metric and image type for both the DEQC head and body phantoms. Underlined text represents those technique parameters further assessed to have a nominally significant effect on the test result for a given image type. Blank cells indicate invalid combinations of test metric and image type, while hyphens indicate combinations where none of the investigated technique parameters were found to be major variance contributors

Phantom	Test metric	50 keV	70 keV	110 keV	140 keV	I(Wa)	Wa(I)
DEQC body phantom	Iodine quant error 2 mg/mL					–	–
	Iodine quant error 5 mg/mL					–	–
	Iodine quant error 15 mg/mL					mAs	–
	Monoenergetic HU stability	mAs	–	mAs	mAs	–	–
	Noisea	CTDIvol	CTDIvol	CTDIvol	CTDIvol	CTDIvol	CTDIvol
	Positional constancy	mAs	–	mAs	mAs	mAs	mAs
DEQC head phantom	Iodine quant error 2 mg/mL					–	–
	Iodine quant error 5 mg/mL					mA	–
	Monoenergetic HU stability	–	–	mAs	mAs	–	–
	Noisea	CTDIvol, mA	CTDIvol, mA	CTDIvol, mA	CTDIvol, mA	CTDIvol, mA	CTDIvol, mA
	Positional constancy	–	–	mA	mA	mA	mA

^aThe nominal significance of CTDIvol and mAs on noise cannot be assessed using this method due to the log transformation of the data.