Table 5.

%Bias, %STD and %RMSE in SPECT measured activity for the experimental phantom with two non-uniform activity spheres (figure 3). The value in parentheses for PL-CT corresponds to the case where only the outer boundary was used for the regularization.

Sphere	OSEM			PL-CT			PL-Q			PL-EP
	Bias	STD	RMSE	Bias	STD	RMSE	Bias	STD	RMSE	Bias	STD	RMSE
Uniform	2	0.8	42	1	0.8	26	12	0.7	31	5	0.7	40
Small non-uniform	−2	0.8	39	−3	0.7	18(49)	13	0.7	42	0	0.7	35
Large non-uniform	14	1.4	42	15	1.4	41(49)	22	1.3	53	18	1.4	47