TABLE 2.

Measured Contrast Recovery Coefficient and Background Variability for 3 and 7 Iterations of OSEM Reconstruction

	Sphere size
Parameter	10 mm	13 mm	17 mm	22 mm	28 mm	37 mm	Lung residual error
Contrast recovery coefficient
3-iteration OSEM
Mean	74.5	82.1	82.6	86.1	89.4	92.6	1.7
Maximum	76.1	84.3	84.7	87.0	89.8	93.1	1.7
Minimum	72.6	80.3	81.5	85.0	88.9	91.6	1.7
7-iteration OSEM
Mean	83.3	85.4	87.2	90.2	92.3	94.8	0.9
Maximum	85.6	87.9	90.3	91.7	92.9	95.5	0.9
Minimum	80.9	82.2	84.9	88.2	91.6	93.4	0.9
Background variability
3-iteration OSEM
Mean	3.1	2.4	1.9	1.6	1.4	1.3	1.4
Maximum	3.4	2.6	2.0	1.7	1.5	1.3	1.4
Minimum	2.6	2.1	1.8	1.5	1.4	1.3	1.4
7-iteration OSEM
Mean	5.0	3.6	2.8	2.2	1.9	1.6	1.9
Maximum	5.4	3.9	3.0	2.4	2.0	1.7	1.9
Minimum	4.2	3.1	2.5	2.1	1.8	1.5	1.8

Results are reported as mean, minimum, and maximum percentages over 3 measurements.