Table 2.

The mean optical densities for all voxels contained within spheres of specified radius representing dose responses from variously sized detectors, for one of the measured 16 mm collimator dose distributions. This data was used to fit and extrapolate the dose response down to the response of a theoretical zero-volume detector. Each data point was weighted proportionately to the square root of the number of voxels contained within that given spherical detector volume.

Radius (voxels)	Mean Optical Density (scaled)	Number of Voxels	√(Voxels)
12	7.64	7249	85.14
11	7.76	5583	74.72
10	7.85	4193	64.75
9	7.92	3055	55.27
8	7.96	2155	46.42
7	7.98	1441	37.96
6	8.00	907	30.12
5.5	8.00	696	26.38
5	8.00	529	23.00
4.5	8.00	379	19.47
3	8.00	118	10.86
2	7.99	35	5.92
1.25	7.99	7	2.65