Table 3. Summary of the quantitative impact of the range and position uncertainties.
The comparison is among the reference IMPT plan, the robust optimised replica p_4mm and p_6mm and the worst-case scenario computed applying to the p_4mm and p_6mm plans the 3% and 4 or 6mm perturbations.
| OARs | Objective | IMPT | IMPT P_4mm |
IMPT RU_4mm | IMPT P_6mm |
IMPT RU_6mm | P |
|---|---|---|---|---|---|---|---|
| CTV Volume: 105±72 [33–306] cm3 | |||||||
| Dmean | 60Gy | 60.0 | 60.0 | 60.0±0.3 | 60.0 | 60.1±1.6 | - |
| D2% [Gy] | Minimize | 61.3±0.4 | 61.8±1.5 | 65.8±4.1 | 62.2±1.6 | 65.9±9.2 | a,b |
| D98% [Gy] | ≥58.8Gy (98%) | 59.0±0.3 | 59.0±0.4 | 59.1±4.4 | 58.7±0.6 | 51.1±13.3 | b |
| V95% [%] | Maximise | 99.9±0.1 | 99.9±0.1 | 99.5±13.2 | 99.8±0.7 | 95.1±9.5 | - |
| HI [%] | <5% | 2.5±0.1 | 3.5±0.2 | 5.6±0.4 | 4.5±0.2 | 7.8±0.8 | a,b |
| Liver-PTV Volume: 1210±266 [725–1672] cm3 | |||||||
| V<21Gy [cm3] | ≥ 700 cm3 | 1093±98 | 1089±105 | 1066±128 | 1081±103 | 1024±146 | a,b |
| Dmean [Gy] | 4.8±3.4 | 5.0±3.3 | 6.0±3.6 | 5.2±3.5 | 7.5±5.5 | a,b | |
IMPT = intensity modulated proton therapy; RU = ranger uncertainty; Dx = dose received by x% or xcm3 of the volume. Dmean = mean dose, V<21Gy = volume receiving less then 21Gy. HI = conformity index.
Statistical significance (p) a = IMPT p_4mm vs IMPT RU_4mm; b = IMPT p_6mm vs IMPT RU_6mm