Table 4.

Prognostic factor associated with radiation pneumonitis

	HR	95% CI	p value		HR	95% CI	p value		HR	95% CI	p value
Average HU				Percentage of area under −950 HU				Percentage of area under −860 HU
≤ −850 HU : >−850 HU	0.40	0.22–0.73	0.003	≤10% :>10%	0.38	0.13–1.10	0.08	≤50% :>50%	0.41	0.21–0.79	0.008
Location				Location				Location
Upper : middle or linguinal and lower lobe	0.80	0.43–1.47	0.47	Upper : middle or linguinal and lower lobe	0.82	0.44–1.51	0.52	Upper : middle or linguinal and lower lobe	0.93	0.50–1.72	0.81
Gender				Gender				Gender
Male: female	0.79	0.44–1.44	0.45	Male: female	0.81	0.44–1.47	0.48	Male: female	0.66	0.36–1.21	0.18
Dose				Dose				Dose
≤78 Gy :>78 Gy	0.80	0.43–1.49	0.49	≤78 Gy :>78 Gy	0.72	0.39–1.33	0.3	≤78 Gy :>78 Gy	0.94	0.48–1.83	0.85
T factor				T factor				T factor
1 : 2	0.89	0.46–1.73	0.73	1 : 2	0.95	0.50–1.81	0.87	1 : 2	0.89	0.46–1.71	0.72

CI, confidence interval; HU, Hounsfield unit; HR, hazard ratio.