射波刀治疗后放射性脑坏死影响因素及其预测因子研究

目的 探讨射波刀治疗后放射性脑坏死影响因素及其预测因子。方法 回顾分析2006—2011年射波刀治疗颅内原发或转移瘤患者 94例(104个靶点)。全部采用颅骨追踪方式、60%~87%剂量线、12~45 Gy、1~8次分割完成。运用影像学或病理学判定放射性脑坏死。采用Logistic回归分析糖尿病、心脑血管疾病、治疗体积、剂量线、处方剂量、分割次数、是否联合WBI、BED与放射性脑坏死的关系;采用ROC曲线测定所有影响因素对放射性脑坏死预测性及临界阈值。结果12个靶点(11.54%)发生放射性脑坏死。回归分析显示治疗BED、是否联合WBI、分割次数是放射性脑坏死的影响因素。ROC曲线显示曲线下面积分别为 0.892±0.034、0.650±0.072、0.712±0.064,仅BED能较好预测放射性脑坏死发生且剂量阈值为>7410 cGy。

A study of influencing factors and predictors for radiation encephalic necrosis after CyberKnife radiotherapy

Objective To investigate the influencing factors and predictors for radiation encephalic necrosis after CyberKnife radiotherapy. Methods Ninety-four patients (104 targets) with primary or metastatic intracranial tumors who were treated with CyberKnife radiotherapy from 2006 to 2011 were retrospectively analyzed. All surgeries adopted skull tracking modes with a dose of 12-45 Gy in 1-8 fractions prescribed to 60%-87% isodose line. Radiation encephalic necrosis was determined by imaging or pathological examination. Logistic regression analysis was used to analyze the relationship between radiation encephalic necrosis and factors including diabetes, cardio-cerebrovascular diseases, target volume, isodose line, prescribed dose, number of fractions, combination with whole-brain irradiation (WBI), and biologically equivalent dose (BED). Predictability and critical threshold of all influencing factors forradiation encephalic necrosis were determined by the receiver operating characteristic (ROC) curve. ResultsTwelve targets (11.54%) had radiation encephalic necrosis. According to the result of logistic regression analysis, BED, combination with WBI, and number of fractions were influencing factors for radiation encephalic necrosis. In the ROC curves, the areas under curves for the above three factors were 0.892±0.034, 0.650±0.072, and 0.712±0.064, respectively, indicating that only BED can well predict radiation encephalic necrosis after CyberKnife radiotherapy with a dose threshold of>7410 cGy. Conclusions BED, combination with WBI, and number of fractions are influencing factors for radiation encephalic necrosis. BED is the best predictor of radiation encephalic necrosis with a dose threshold of>7410 cGy.