Table 3.
Mean (±SD) values for the various plan quality metrics evaluated in this study
| Dosimetric index | Definition | Mean | SD | 95% CI | Correlation with PTV (p-value) | |
| Lower | Upper | |||||
| Coverage | Quality of coverage | 0.90 | 0.08 | 0.88 | 0.91 | <0.0001 |
| Coverage, % | 96.7 | 1.92 | 95.90 | 96.90 | 0.09 | |
| Homogeneity | HIRTOG | 1.27 | 0.07 | 1.26 | 1.29 | 0.02 |
| HIICRU83 | 0.21 | 0.06 | 0.20 | 0.23 | 0.08 | |
| Conformity indices | CIRTOG | 1.03 | 0.07 | 1.02 | 1.05 | 0.06 |
| CIPaddick | 0.91 | 0.04 | 0.89 | 0.93 | 0.02 | |
| CIgeometric (g) | 0.11 | 0.06 | 0.10 | 0.13 | 0.0003 | |
| CN | 0.90 | 0.06 | 0.89 | 0.91 | 0.03 | |
| CGIc | 97.4 | 5.90 | 95.5 | 98.2 | 0.05 | |
| CILomax | 0.94 | 0.05 | 0.92 | 0.94 | 0.06 | |
| Gradient | R50% (RTOG) | 4.40 | 0.70 | 4.27 | 4.58 | <0.0001 |
| Gradient index | 4.20 | 0.60 | 4.14 | 4.37 | <0.0001 | |
| Gradient (cm) | 1.20 | 0.30 | 1.21 | 1.33 | <0.0001 | |
| Gradienteff (% cm−1) | 42.3 | 9.40 | 39.60 | 43.18 | <0.0001 | |
| Low dose Spillage (%) | D2 cm (%) | 54.90 | 10.70 | 54.00 | 58.50 | <0.0001 |
| High dose spillage (%) | (V105% PD - PTV)/PTV | 0.90 | 1.70 | 0.61 | 1.27 | 0.30 |
| Total lung dose (%) | V20 Gy | 4.80 | 3.20 | 4.34 | 5.58 | <0.0001 |
| V5 Gy | 16.40 | 9.20 | 15.10 | 18.67 | <0.0001 | |
CI, conformity index; CN, confirmation number; HI, homogeneity index; PTV, planning target volume; RTOG, radiation therapy oncology group.