Effect of Different Breast Densities and Average Glandular Dose on Contrast to Noise Ratios in Full-Field Digital Mammography: Simulation and Phantom Study

Table 6

Results of multivariate linear regression analysis using CNR as the objective variable and mammary gland ratio, AGD, and phantom thickness as the explanatory variables.

		Regression results				Analysis of variance
Variable	Level	Regression coefficient	Lower limit of 95% confidence interval	Upper limit of 95% confidence interval	Wald test p value	Contribution rate	Chi-squared test p value
Constant term	-	24.489	21.929	27.049	7.720E-13	-	-
Phantom type	B	-1.276	-2.665	0.112	6.911E-02	3.63%	1.213.E-02
Phantom type	C	-2.146	-3.499	-0.792	3.976E-03	-	-
Phantom thickness	-	-0.228	-0.321	-0.136	8.041E-05	91.43%	9.500.E-12
AGD	-	0.311	-4.402	5.025	8.904E-01	0.01%	8.904.E-01

AGD: average glandular dose and CNR: contrast to noise ratio.