Table 1. Results of the semi-quantitative analysis of the phantom studies.

		actual SBR	measured SBR
centre	method		left	right	measured/actual SBR (%)a
Berlin	no AC	5.47	2.30	2.09	40.1
	CT-based	5.47	2.55	2.37	45.0
	Chang	5.47	2.88	2.62	50.3
Leipzig	no AC	5.74	2.57	2.36	42.9
	CT-based	5.74	2.92	2.53	47.5
	Chang	5.74	3.04	2.88	51.6
Rostock	no AC	5.19	2.36	2.40	45.9
	CT-based	5.19	2.60	2.64	50.5
	Chang	5.19	2.85	2.86	55.0
mean	no AC				43.0±2.9
	CT-based				47.6±2.8
	Chang				52.3±2.4

The specific-to-background ratio (SBR) was measured using the same whole striatum ROIs as in the patient studies (Fig. 1).

^ameasured SBR: mean over left and right hemisphere.