Table 3.
Field size factor (FSF) for selected options
| Option | Field size | |||||
|---|---|---|---|---|---|---|
| 3.5 cm diameter circular | 5 × 5 cm2 | 10 × 10 cm2 | 14 cm diameter circular | 20 × 20 cm2 | 25 cm diameter circular | |
| 1 | 0.687 | 0.985 | 1.000 | 1.000 | 1.000 | 1.000 |
| 6 | 0.868 | 1.006 | 1.004 | 1.000 | 1.000 | 0.996 |
| 12 | 0.903a | 1.019a | 1.016 | 0.999 | 1.000 | 0.999 |
| 13 | 0.656 | 0.982 | 1.000 | 1.000 | 1.000 | 1.000 |
| 15 | 0.700 | 0.971 | 1.000 | 1.000 | 1.000 | 1.000 |
| 17 | 0.778 | 0.984 | 1.000 | 1.000 | 1.000 | 1.000 |
| 18 | 0.758 | 0.989 | 1.000 | 1.000 | 1.000 | 1.000 |
| 20 | 0.938 | 1.003 | 1.000 | 1.000 | 1.000 | 1.000 |
| 24 | 1.015a | 1.011a | 1.000 | 1.000 | 1.000 | 1.000 |
a
Relatively higher readings may come from the slit scattering for the detector at shallow depths. The reference field sizes are marked in bold.