Table 8.

Average relative squared error (RSE) and structural similarity index (SSIM).

Breast type	$c_{\text{breast}}$ ($\mathrm{mm}/\mu \mathrm{s}$)	RSE			SSIM
		Approach 1	Approach 2	Approach 3	Approach 1	Approach 2	Approach 3
A	1.47	0.4605	0.4550	0.3637	0.9808	0.9827	0.9838
B	1.475	0.4296	0.4275	0.3256	0.9790	0.9801	0.9833
C	1.495	0.4291	0.4146	0.3238	0.9798	0.9807	0.9834
D	1.53	0.3552	0.3464	0.2699	0.9801	0.9801	0.9835

$c_{\text{breast}}$: breast sound speed used in Approach 2.