Table 3.

Inter-observer variability, from comparisons between contours of the spinal cord drawn by each of six oncologists and the contours drawn by the other five. The numbers of MVCT scans and slices relative to each comparison are shown. Results are given for the median and mean of the conformity index, and of the distance between centres (mm); and for the mean of the difference (mm) in left–right dimensions, and of the difference (mm) in anterior-posterior dimensions. Quoted uncertainties are statistical.

Observer	1	2	3
Patients	3	3	3
Scans	6	6	6
Slices	133	133	133
Median CI	$0.723\pm 0.007$	$0.763\pm 0.005$	$0.753\pm 0.005$
Mean CI	$0.713\pm 0.005$	$0.756\pm 0.004$	$0.742\pm 0.004$
Median DBC	$1.02\pm 0.05$	$0.82\pm 0.03$	$0.88\pm 0.03$
Mean DBC	$1.06\pm 0.04$	$0.89\pm 0.03$	$0.90\pm 0.02$
Mean L-R diff	$-0.1\pm 0.1$	$0.2\pm 0.1$	$-1.4\pm 0.1$
Mean A-P diff	$-1.4\pm 0.1$	$-0.3\pm 0.1$	$-0.2\pm 0.1$

Observer	4	5	6
Patients	3	3	3
Scans	6	6	6
Slices	133	133	133
Median CI	$0.764\pm 0.005$	$0.745\pm 0.006$	$0.651\pm 0.009$
Mean CI	$0.756\pm 0.004$	$0.739\pm 0.004$	$0.643\pm 0.007$
Median DBC	$0.91\pm 0.03$	$0.90\pm 0.04$	$1.24\pm 0.06$
Mean DBC	$0.94\pm 0.02$	$0.96\pm 0.03$	$1.32\pm 0.05$
Mean L-R diff	$-0.1\pm 0.1$	$-0.4\pm 0.1$	$1.7\pm 0.2$
Mean A-P diff	$-0.2\pm 0.1$	$-0.1\pm 0.1$	$2.2\pm 0.1$