A retrospective dosimetry study of intensity-modulated radiotherapy for nasopharyngeal carcinoma: radiation-induced brainstem injury and dose-volume analysis

Table 2 Analysis on radiation dose and other factors affecting brainstem toxicities in Cox regression models

Factor	p-value	HR	95% CI for HR
T category(T₄ vs T_1–3)	0.029	5.94	1.2–29.43
GTVnx D_2%	0.040	1.21	1.01–1.45
D_max	0.003	1.15	1.05–1.26
D_1%	0.003	1.16	1.05–1.28
D_0.1cc	0.003	1.16	1.05–1.27
D_1cc	0.006	1.15	1.04–1.27

D _2% near the maximum absorbed dose of GTV_nx, D_max the maximum point dose of brainstem,
D_1% the dose of 1% brainstem volume, D_0.1cc the maximum dose of brainstem delivered to a volume of 0.1 ml, D_1cc the maximum dose of brainstem delivered to a volume of 1.0 ml, GTVnx
Gross tumor volume of nasopharyngeal primary lesions and their direct extensions
Abbreviation: HR hazard ratio, CI confidence interval, GTV Gross tumor volume

ISSN: 1748-717X