Table 2. Comparison of planning parameters at three levels of IDS.
| 90% |
80% |
70% |
|||||
| Parameter | Mean±SD (range) | p-valuea | Mean±SD (range) | p-valuea | Mean±SD (range) | KW test p-value | JT test p-value (↑/↓)b |
| Target coverage (%) | 99.1±0.1 | 99.2±0.1 | 99.2±0.1 | 0.601 | |||
| (99.0–99.3) | (99.0–99.6) | (99.0–99.4) | |||||
| 0.343 | 0.944 | ||||||
| CI | 1.22±0.06 | 1.16±0.05 | 1.16±0.05 | 0.027 | 0.005 | ||
| (1.14–1.30) | (1.08–1.23) | (1.07–1.24) | (↓) | ||||
| 0.001 | 0.691 | ||||||
| HI | 0.13±0.01 | 0.22±0.01 | 0.33±0.01 | <0.001 | <0.001 | ||
| (0.11–0.15) | (0.21–0.25) | (0.32–0.34) | (↑) | ||||
| 0.001 | 0.001 | ||||||
| TV Dmean (%) | 108.0±1.30 | 117.9±1.3 | 129.5±1.9 | <0.001 | <0.001 | ||
| (104.0–109.1) | (115.1–119.7) | (125.8–132.5) | (↑) | ||||
| <0.001 | <0.001 | ||||||
| Int. rind Dmean (%) | 106.7±0.70 | 113.5±1.2 | 121.1±2.1 | <0.001 | <0.001 | ||
| (105.5–108.0) | (111.6–115.4) | (117.6–124.3) | (↑) | ||||
| <0.001 | <0.001 | ||||||
| Ext rind Dmean (%) | 94.0±2.20 | 88.1±2.7 | 86.0±3.2 | <0.001 | <0.001 | ||
| (89.9–97.4) | (83.2–91.9) | (81.2–90.6) | (↓) | ||||
| <0.001 | <0.001 | ||||||
| 75% IDV/100% IDV | 1.72±0.18 | 1.52±0.08 | 1.45±0.06 | <0.001 | <0.001 | ||
| (1.27–2.08) | (1.41–1.70) | (1.32–1.57) | (↓) | ||||
| 0.006 | <0.001 | ||||||
| 75% IDV/TV | 2.10±0.26 | 1.76±0.12 | 1.68±0.12 | <0.001 | <0.001 | ||
| (1.46–2.46) | (1.54–1.93) | (1.46–1.84) | (↓) | ||||
| 0.001 | <0.001 | ||||||
| 50% IDV/100% IDV | 2.87±0.30 | 2.51±0.18 | 2.42±0.11 | <0.001 | <0.001 | ||
| (PGI) | (2.46–3.53) | (2.28–2.94) | (2.27–2.67) | (↓) | |||
| <0.001 | <0.001 | ||||||
| 50% IDV/TV | 3.50±0.38 | 2.91±0.24 | 2.80±0.19 | <0.001 | <0.001 | ||
| (mGI) | (2.84–4.17) | (2.48–3.29) | (2.43–3.09) | (↓) | |||
| <0.001 | <0.001 | ||||||
| 25% IDV/100% IDV | 7.47±0.85 | 6.87±0.69 | 6.69±0.44 | 0.012 | 0.003 | ||
| (6.15–9.23) | (5.59–8.35) | (5.88–7.4) | (↓) | ||||
| 0.001 | 0.078 | ||||||
| 25% IDV/TV | 9.12±1.02 | 7.96±0.74 | 7.75±0.54 | 0.001 | <0.001 | ||
| (7.68–11.18) | (6.74–9.34) | (7.01–8.58) | (↓) | ||||
| 0.001 | 0.054 | ||||||
CI, conformity index; Dmean, mean dose; Ext., exterior; HI, homogeneity index; IDS, isodose surface; IDV, isodose volume; Int., interior; JT test, Jonckheere–Terpstra test; KW test, Kruskal–Wallis test; mGI, modified gradient index; PGI, Paddick's gradient index; SD, standard deviation; TV, target volume.
Values are mean±SD (range).
Significant p-values are shown in bold.
aWilcoxon signed-rank test (p<0.016 considered significant based on Bonferroni's correction for multiple comparison).
bIncreased (↑) or decreased (↓) trends in the results from Jonckheere–Terpstra test.