TABLE 3.
Absorbed dose to water measured by clinically used plane‐parallel plate ion chambers, Advanced Markus and PPC05, and the ratios of the absorbed dose determined with ion chambers to the absorbed dose measured with the National Physical Laboratory (NPL) proton calorimeter
| Chamber | Field size (cm × cm) | Dose to water (Gy) | SDOM (Gy) | Ratio (chamber/calorimeter) | Average ratio |
|---|---|---|---|---|---|
| Advanced Markus | 5 × 6 | 7.694 | 0.053 | 1.005 ± 0.007 | 1.002 ± 0.007 |
| 5 × 8 | 7.710 | 0.054 | 1.003 ± 0.007 | ||
| 5 × 10 | 7.769 | 0.054 | 1.006 ± 0.007 | ||
| 5 × 12 | 7.701 | 0.054 | 0.995 ± 0.007 | ||
| 6 × 5 | 7.685 | 0.053 | 1.002 ± 0.007 | ||
| 12 × 5 | 7.746 | 0.054 | 1.001 ± 0.007 | ||
| PPC05 | 5 × 6 | 7.923 | 0.055 | 1.035 ± 0.007 | 1.033 ± 0.007 |
| 5 × 8 | 7.954 | 0.056 | 1.034 ± 0.007 | ||
| 5 × 10 | 7.968 | 0.056 | 1.031 ± 0.007 | ||
| 5 × 12 | 7.971 | 0.056 | 1.030 ± 0.007 | ||
| 6 × 5 | 7.934 | 0.055 | 1.035 ± 0.007 | ||
| 12 × 5 | 7.991 | 0.056 | 1.032 ± 0.007 |
Abbreviation: SDOM, standard deviation of the mean.