Table 2.

Summary of Measurement Parameters for Evaluated DQE Methods

Overall DQE Method	IEC Apertures	Beam Quality*	MTF Device	MTF Analysis Method	NPS Analysis Method	NPS Analysis Area†	ROI Size and Type‡	NPS Band Size§	NPS Detrending
Dobbins et al	None	70 kV 0.5 mm Cu	Slit	Dobbins et al	Dobbins et al	640 × 640 Pixels (10)	128 Pixels, NOL	±4	Two-dimensional (first order)
						1024 × 1024 Pixels (1)
Samei and Flynn	None	70 kV 19 mm Al	Radiolucent edge	Samei and Flynn	Samei and Flynn
Historical						640 × 640 Pixels (10)	128 Pixels, NOL	±7 With on-axis data	Two-dimensional (second order)
						1280 × 1280 Pixels (1)
Current						640 × 640 Pixels (3)	128 Pixels, OL
						1280 × 1280 Pixels (1)
IEC||	External	RQA5	Radiopaque edge	IEC	IEC	640 × 640 Pixels (3)	256 Pixels, OL	±7	Two-dimensional (second order)
						640 × 640 Pixels (10)

Note.—Parameters used in the Dobbins et al (8), Samei and Flynn (13), and IEC (4) methods are given.

^*Cu = copper, Al = aluminum.

^†The first set of parameters corresponds to the parameters employed for the evaluation of the NPS and combined NPS plus MTF dependence on the DQE estimate. Comparable statistical quality in the NPS estimates was achieved by varying the relative number of images analyzed with each method (5). The second set of parameters corresponds to results regarding the effect of the overall DQE method. The number of images analyzed was indicated by the specifications of each image, or in the case of the IEC method, by the requirement to use a total of at least 4 million independent image pixels in the NPS analysis. The number of images used is in parentheses.

^‡NOL = nonoverlapping (one pass) ROIs, OL = overlapping (four passes) ROIs.

^§Number of rows of data averaged in two-dimensional NPS to produce a one-dimensional NPS curve.

^||The IEC method requires the use of 256 × 256-pixel ROIs for NPS analysis involving the use of an overlapping placement scheme achieved with four successive analysis passes with ROIs offset as follows: (x, y); x + 128, y; x, y + 128; and x + 128, y + 128. x And y are the reference coordinates for the top left-most corner of the analysis area.