Stein Sherman C, Hurst Robert W, Sonnad Seema S
Department of Neurosurgery, University of Pennsylvania School of Medicine, Philadelphia, PA 19106, USA.
Pediatr Neurosurg. 2008;44(6):448-57. doi: 10.1159/000172967. Epub 2008 Nov 17.
We aimed to estimate the risks of radiation exposure from a single head CT scan to children of different ages.
We constructed a multistate time-dependent Markov model to simulate the course of children exposed to a head CT. The relevant literature was reviewed for probabilities, which were used to calculate tumor types, latencies after exposure and outcomes in the model. Where multiple approximations of the same probability had been reported, meta-analytic techniques were employed to compute pooled estimates. The model was then used to calculate the effect of the radiation exposure on life expectancy and quality of life for children following head CT at different ages.
The tumors likely to be induced by low-level cranial irradiation include thyroid carcinoma (47%), meningioma (34%) and glioma (19%). According to the model, a single head CT is likely to cause one of these tumors in 0.22% of 1-year-olds, 30% of whom will consequently die. The exposure will shorten the life expectancy of all exposed 1-year-olds by an average of 0.04 years and their expected quality of life by 0.02 quality-adjusted life years. The risks of radiation exposure diminish for older children.
The model predicts that the effective radiation dose from a single head CT is capable of inducing a thyroid or brain tumor in an infant or child. These tumors can severely impact both quality of life and life expectancy. Care should be taken before ordering CT scans in children, particularly in infants and toddlers.
我们旨在评估单次头部CT扫描对不同年龄段儿童的辐射暴露风险。
我们构建了一个多状态时间依赖性马尔可夫模型，以模拟接受头部CT检查的儿童的病程。查阅相关文献获取概率数据，用于计算模型中的肿瘤类型、暴露后的潜伏期和结果。当报告了同一概率的多个近似值时，采用荟萃分析技术计算合并估计值。然后使用该模型计算不同年龄段儿童头部CT扫描后辐射暴露对预期寿命和生活质量的影响。
低水平颅脑照射可能诱发的肿瘤包括甲状腺癌（47%）、脑膜瘤（34%）和胶质瘤（19%）。根据该模型，单次头部CT扫描可能导致1岁儿童中0.22%发生这些肿瘤中的一种，其中30%最终会死亡。这种暴露将使所有接受扫描的1岁儿童的预期寿命平均缩短0.04年，预期生活质量降低0.02个质量调整生命年。年龄较大儿童的辐射暴露风险降低。
该模型预测，单次头部CT扫描的有效辐射剂量能够在婴儿或儿童中诱发甲状腺或脑肿瘤。这些肿瘤会严重影响生活质量和预期寿命。在为儿童，尤其是婴幼儿安排CT扫描之前应谨慎。
