Table 4 Dosimetric criteria associated with lower risk for hypothyroidism in patients with pre-irradiation thyroid volumes ≥ 8 cc
Dosimetric parameter | Low-risk group definition | Log-rank p value | 3-year freedom from HT | Lower 95% CI | Upper 95% CI |
|---|---|---|---|---|---|
VS45 Gy | ≥3 cc | 0.035 | 65.0% | 36.0% | 82.5% |
VS50 Gy | ≥5 cc | 0.037 | 65.0% | 36.0% | 82.5% |
VS50 Gy | ≥6 cc | 0.035 | 61.5% | 35.5% | 80.5% |
V50 Gy | <45% | 0.041 | 71.5% | 39.2% | 88.5% |
V50 Gy | <55% | 0.050 | 69.5% | 41.0% | 86.3% |
Mean Dose | <49 Gy | 0.041 | 71.0% | 39.5% | 88.5% |