每年有超过一百万欧洲儿童接受计算机断层扫描 (CT)。尽管中高剂量电离辐射暴露是血液系统恶性肿瘤的既定危险因素，但 CT 检查剂量水平的风险仍不确定。在这里，我们对来自九个欧洲国家的 948,174 名 22 岁之前接受 CT 检查的跨国队列 (EPI-CT) 进行了随访。根据扫描的身体部位、患者特征、时间段和推断的 CT 技术参数来估计活性骨髓的辐射剂量。我们发现累积剂量与所有血液系统恶性肿瘤的风险之间存在关联，每 100 mGy（790 例）的相对风险为 1.96（95% 置信区间 1.10 至 3.12）。对于淋巴和骨髓恶性肿瘤也获得了类似的估计。结果表明，目前每 10,000 名接受检查的儿童（平均剂量 8 mGy）中，预计将有 1-2 人在接下来的 12 年内因辐射暴露而患上血液恶性肿瘤。我们的结果强化了低辐射剂量下癌症风险增加的证据，并强调需要继续证明儿科 CT 检查和优化剂量的合理性。© 2023。作者。

Over one million European children undergo computed tomography (CT) scans annually. Although moderate- to high-dose ionizing radiation exposure is an established risk factor for hematological malignancies, risks at CT examination dose levels remain uncertain. Here we followed up a multinational cohort (EPI-CT) of 948,174 individuals who underwent CT examinations before age 22 years in nine European countries. Radiation doses to the active bone marrow were estimated on the basis of body part scanned, patient characteristics, time period and inferred CT technical parameters. We found an association between cumulative dose and risk of all hematological malignancies, with an excess relative risk of 1.96 (95% confidence interval 1.10 to 3.12) per 100 mGy (790 cases). Similar estimates were obtained for lymphoid and myeloid malignancies. Results suggest that for every 10,000 children examined today (mean dose 8 mGy), 1-2 persons are expected to develop a hematological malignancy attributable to radiation exposure in the subsequent 12 years. Our results strengthen the body of evidence of increased cancer risk at low radiation doses and highlight the need for continued justification of pediatric CT examinations and optimization of doses.© 2023. The Author(s).