Table 1.
Peak spot dose in cGy/MU at different depths for PPBSs of five different energies measured by ion chamber (IC) by placing it both at the peak of the single PPBS and the center of a 10 × 10 cm2 broad field. Spot spacing of 5 mm was used in creating the broad field. The nominal range corresponds to the depth of 90% Bragg peak dose location.
| Energy (MeV)/nominal range (cm) | Depth (cm) | D0 from IC at peak of single spot (cGy/MU) | D0 from IC in 10 × 10 cm2 field (cGy/MU) | Overall uncertainty ±(%) |
|---|---|---|---|---|
| 72.5/4.0 | 2 | 5.60 | 5.85 | 1.90 |
| 72.5/4.0 | 3 | 7.18 | 7.42 | 4.38 |
| 89.6/6.0 | 2 | 7.31 | 7.74 | 0.73 |
| 89.6/6.0 | 3 | 8.02 | 8.08 | 1.03 |
| 89.6/6.0 | 4 | 9.17 | 9.27 | 1.94 |
| 146.9/14.9 | 2 | 16.33 | 17.26 | 0.18 |
| 146.9/14.9 | 7 | 17.33 | 18.20 | 0.31 |
| 146.9/14.9 | 12 | 21.24 | 21.25 | 1.17 |
| 181.1/21.5 | 2 | 21.78 | 22.55 | 0.23 |
| 181.1/21.5 | 4 | 21.61 | 22.33 | 0.10 |
| 181.1/21.5 | 19 | 26.13 | 27.90 | 1.35 |
| 221.8/30.6 | 2 | 31.58 | 33.83 | 0.15 |
| 221.8/30.6 | 10 | 29.52 | 31.24 | 0.10 |
| 221.8/30.6 | 20 | 24.74 | 26.05 | 0.14 |