Table 1.

Manufacturer and exposure index parameters used for digital radiography systems

Manufacturer	Exposure indicator name	Symbol	Units	Exposure dependence, X	Detector calibration conditions
Fujifilm	S value	S	Unitless	200/S ∝ X (mR)	80 kVp, 3 mm Al “total filtration” S = 200 @ 1 mR
Carestream	Exposure index	EI	Mbels	EI + 300 = 2X	80 kVp, 1.0 mm Al + 0.5 mm Cu; EI = 2000 @ 1 mR
Agfa	Log of median of histogram	lgM	Bels	lgM + 0.3 = 2X	400 speed class, 75 kVp + 1.5 mm Cu; lgM = 1.96 @ 2.5 μGy
Konica	Sensitivity number	S	Unitless	For QR = k, 200/S ∝ X(mR)	QR = 200, 80 kVp, S = 200 @ 1 mR
Canon	Reached exposure value	REX	Unitless	Brightness = c1, Contrast = c2, REX ∝ X1	Brightness = 16
					Contrast = 10
					REX ≈ 106 @ 1 mR1
Canon	EXP	EXP	Unitless	EXP ∝ X	80 kVp, 26 mm Al, HVL = 8.2 mm Al, DFEI = 1.5
					EXP = 2000 @ 1 mR
GE	Uncompensated detector exposure	UDExp	μGy air kerma	UDExp ∝ X (μGy)	80 kVp, standard filtration, no grid
GE	Compensated detector exposure	CDExp	μGy air kerma	CDExp ∝ X (μGy)	Not available
GE	Detector exposure index	DEI	Unitless	DEI ≈ratio of actual exposure to expected exposure scaled by technique and system parameters. Expected exposure values can be edited by user as preferences.	Not available
Swissray	Dose indicator	DI	Unitless	Not available	Not available
Imaging Dynamics	Accutech	F#	Unitless	2f# = X(mR)/Xtgt(mR)	80 kVp + 1 mm Cu
Philips	Exposure index	EI	Unitless	1000/X (μGy)	RQA5, 70 kV, + 21 mm Al, HVL = 7.1 mm Al
Siemens	Exposure index	EXI	μGy air kerma	X(μGy) = EI/100	RQA5, 70 kV + 0.6 mm Cu, HVL = 6.8 mm Al
Alara CR	Exposure indicator value	EIV	Mbels	EIV + 300 = 2X	1 mR at RQA5, 70 kV, + 21 mm Al, HVL = 7.1 mm Al = > EIV = 2000
iCRco	Exposure index	None	Unitless	Exposure index ∝ log[X (mR)]	1 mR @ 80 kVp + 1.5 mm Cu => 0