Table 4.
Optimal cut-off values and area under the curve (AUC) values derived from ROC analysis
| Metrics | Cut-off values | Crude incidence rate of symptomatic RP |
AUC values | |
|---|---|---|---|---|
| ≤Cut-off | >Cut-off | |||
| MTD | 27.0 mm | 4.5% | 33.3% | 0.762 |
| GTV | 7.9 cm3 | 2.6% | 29.4% | 0.805 |
| PTV | 41.7 cm3 | 2.1% | 62.5% | 0.873 |
| MLD | 3.6 Gy | 0.0% | 30.0% | 0.908 |
| V50 | 0.7% | 2.3% | 38.5% | 0.843 |
| V45 | 1.1% | 2.3% | 41.7% | 0.875 |
| V40 | 1.5% | 2.2% | 50.0% | 0.902 |
| V35 | 1.9% | 2.2% | 45.5% | 0.907 |
| V30 | 2.5% | 2.2% | 45.5% | 0.918 |
| V25 | 3.4% | 2.2% | 50.0% | 0.923 |
| V20 | 3.5% | 0.0% | 28.6% | 0.917 |
| V15 | 5.1% | 0.0% | 26.1% | 0.905 |
| V10 | 9.1% | 0.0% | 28.6% | 0.89 |
| V5 | 21.5% | 2.4% | 33.3% | 0.833 |
GTV, gross tumour volume; MLD, mean lung dose; MTD, maximum tumour diameter; PTV, planning target volume; ROC, receiver-operating characteristic; RP, radiation pneumonitis; Vx, normal lung volume receiving x Gy of radiation.