Table 5.
Results for parameter estimates of linear-quadratic dose–response model for complex exchanges, and relative biological effectiveness (RBE) factors for protons of different energies compared to acute γ-rays.
| Radiation type | α (Gy−1) | β (Gy−2) | RBEγAcute |
|---|---|---|---|
| γ-Rays acute | 0.015 ± 0.005 | 0.025 ± 0.014 | – |
| Proton, 5 MeV | 0.039 ± 0.004 | 0.006 ± 0.017 | 2.56 ± 0.85 |
| Proton, 120 MeVa | 0.032 ± 0.0043 | 0.024 ± 0.01 | 2.1 ± 0.28 |
| Proton, 250 MeV | 0.055 ± 0.009 | 0.03 ± 0.017 | 3.59 ± 1.3 |
| Proton, 800 MeV | 0.029 ± 0.010 | 0.02 ± 0.017 | 1.92 ± 0.87 |
| Proton, 1000 MeV | 0.06 ± 0.016 | 0.046 ± 0.022 | 3.96 ± 1.64 |
| Proton, 2000 MeV | 0.063 ± 0.009 | 0.028 ± 0.017 | 4.12 ± 1.41 |
| Proton, 2500 MeV | 0.058 ± 0.006 | 0.026 ± 0.01 | 3.81 ± 1.26 |
RBEmax was not determined because low dose-rate γ-rays have very low induction of complex exchanges.
a150 MeV proton beam with 5 cm polyethylene shielding leading to residual energy at samples of 120 MeV.