Table 1.
Summary of measured dose rates at a subset of measured depths (a) and 20–80% radiation penumbrae at a depth of 1.03 cm (b). Reported dose rates are averages within a square region measuring 1.77 mm squared (29 × 29 square pixels), although for the smallest two apertures the stated values are peak dose rates. Dose rate errors correspond to 1σ statistical variations over this averaging region, where applicable. Penumbra widths are average values between the x and y profiles.
| Depth | Collimator | 0.16 mm Cu filtration
|
0.25 mm Cu filtration | |
|---|---|---|---|---|
| SSD = 34 cm | SSD = 38 cm | SSD = 34 cm | ||
| (a) Dose rates (cGy min−1) | ||||
| 1.03 cm | 0.5 mm | 102 | 58.0 | – |
| 1.0 mm | 170 | 149 | 138 | |
| 3 × 3 mm | 222 (±7.4) | 174 (±4.2) | 164 (±4.3) | |
| 5 × 5 mm | 228 (±5.9) | 200 (±6.0) | 177 (±6.7) | |
| 5 × 10 mm | 207 (±5.4) | – | – | |
| 2.07 cm | 0.5 mm | 66.2 | 40.0 | – |
| 1.0 mm | 126 | 105 | 107 | |
| 3 × 3 mm | 167 (±5.6) | 134 (±3.9) | 124 (±3.6) | |
| 5 × 5 mm | 170 (±5.5) | 139 (±3.5) | 123 (±3.6) | |
| 5 × 10 mm | 170 (±4.8) | – | – | |
| 4.11 cm | 0.5 mm | 36.9 | 20.7 | – |
| 1.0 mm | 81.3 | 62.1 | 66.3 | |
| 3 × 3 mm | 96.2 (±2.2) | 81.2 (±2.2) | 79.4 (±2.2) | |
| 5 × 5 mm | 101 (±2.4) | 85.1 (±2.2) | 78 (±2.0) | |
| 5 × 10 mm | 105 (±2.7) | – | – | |
| 6.15 cm | 0.5 mm | 18.7 | 10.9 | – |
| 1.0 mm | 53.4 | 35.7 | 43.3 | |
| 3 × 3 mm | 63.2 (±1.4) | 49.9 (±1.1) | 49.4 (±1.1) | |
| 5 × 5 mm | 68.0 (±1.5) | 52.2 (±1.3) | 50.5 (±1.3) | |
| 5 × 10 mm | 65.0 (±1.9) | – | – | |
| (b) Average 20–80% penumbrae (mm) | ||||
| 1.03 cm | 0.5 mm | 0.17 | 0.19 | – |
| 1.0 mm | 0.22 | 0.35 | 0.24 | |
| 3 × 3 mm | 0.29 | 0.51 | 0.27 | |
| 5 × 5 mm | 0.30 | 0.49 | 0.32 | |
| 5 × 10 mm | 0.37 | – | – | |