TABLE IX.
Electron air gap factor table. Air gap factor versus field size (defined at SSD = 100 cm) and SSD for a 9 MeV electron beam on a Varian Clinac 2100C. Values for fair < 0.95 are italicized to indicate conditions of lateral electronic disequlibrium. Taken from Ref. 45.
| Field size | SSD (cm) | ||||
|---|---|---|---|---|---|
| (cm2) | 100 | 105 | 110 | 115 | 120 |
| 2 × 2 | 1.000 | 0.882 | 0.743 | 0.611 | 0.505 |
| 3 × 3 | 1.000 | 0.946 | 0.878 | 0.792 | 0.715 |
| 4 × 4 | 1.000 | 0.942 | 0.902 | 0.862 | 0.815 |
| 6 × 6 | 1.000 | 0.978 | 0.954 | 0.940 | 0.915 |
| 10 × 10 | 1.000 | 0.984 | 0.972 | 0.961 | 0.955 |
| 15 × 15 | 1.000 | 0.988 | 0.978 | 0.970 | 0.963 |
| 20 × 20 | 1.000 | 0.987 | 0.975 | 0.971 | 0.963 |
| 25 × 25 | 1.000 | 0.987 | 0.982 | 0.974 | 0.970 |