Canadian Fluoroscopy Cohort Study: Lifespan Mortality and Incidence Follow-Up

 描述（由申请方提供）：加拿大荧光透视队列研究（CFCS）的拟议更新将解决诊断成像程序长期辐射暴露的长期健康风险知识方面的关键差距。计算机X射线断层扫描（CT）的兴起是显着的，仅在美国每年进行的检查就超过8500万次。高剂量伽马辐射与癌症风险增加之间的因果关系已得到明确确立，但长时间低剂量X射线辐射照射的风险仍未确定。当前的CT扫描辐射安全标准在很大程度上基于对1945年日本原子弹（原子弹）幸存者暴露于瞬时高能伽马辐射的研究。国家和国际辐射防护机构建议将根据原子弹数据预测的CT扫描的超额风险估计值降低1.5-2.0倍，尽管最近对职业受照工人的研究表明，无论剂量延长多少，每单位辐射剂量的风险都类似。因此，这些风险预测可能会低估癌症风险150- 200%。最近发表的研究报告称，儿童多次CT扫描后白血病风险显著增加，这引起了人们的担忧，因为缺乏个体剂量测定以及可能受到适应症或反向因果关系的混淆。成年人的风险以及美国人口中最常见的癌症肺癌和乳腺癌的风险仍然不确定。为了提供清晰度并解决我们知识中的重要空白，我们建议延长死亡率 对1930-1952年接受重复诊断性成像透视检查的63，707例CFCS患者进行额外30年随访（1950-2017年共68年），并进行首次发病率随访（1969-2017年）。我们将利用CFCS的大尺寸、长期随访、个人剂量评估以及透视和CT扫描之间辐射暴露的相似性，获得前所未有的机会来进行辐射风险的生命过程检查。为了实现CFCS的目标，我们将开发一种新的荧光透视X射线器官特异性（FLUXOR）剂量测定系统，并将该队列与覆盖加拿大整个人口的加拿大死亡率和发病率数据库联系起来。除了对多个器官的辐射剂量外，我们还将获得关于可改变的风险因素（如吸烟）的独特数据，以评估癌症结局的多因素病因。估计的辐射风险的适用性 将通过将CFCS数据与来自马萨诸塞州荧光透视队列研究的数据（n= 13，385）合并，进一步检查队列中美国普通人群的数据。高效率的研究设计将提供关于长期辐射照射的寿命风险的重要和以前没有的科学证据。该研究小组包括辐射流行病学、生物统计学和剂量学方面的专家，在评估诊断成像程序，特别是CT扫描的现行辐射安全标准是否适当方面具有独特的资格。

 DESCRIPTION (provided by applicant): The proposed update of the Canadian Fluoroscopy Cohort Study (CFCS) will address critical gaps in knowledge of the long-term health risks of protracted radiation exposures from diagnostic imaging procedures. The rise of computerized X-ray tomography (CT) is remarkable with well over 85 million examinations per year performed in the United States alone. The causal association between high doses of gamma radiation and increased risks of cancer are firmly established, but the risks of low-dose X-ray radiation exposures protracted over a period of time remain undetermined. Current radiation safety standards for CT scans are based in large part on the study of Japanese atomic bomb (A-bomb) survivors exposed in 1945 to instantaneous high- energy gamma radiation. National and international radiation protection agencies recommend reducing estimates of excess risks from CT scans projected from the A-bomb data by a factor of 1.5-2.0, although recent studies of occupationally exposed workers show similar risks per unit of radiation dose irrespective of the dose protraction. Thus, potentially, these risk projection could underestimate cancer risks by 150-200%. Recently published studies reporting significantly increased risks of leukemia after multiple CT scans in children have raised concerns because of the absence of individual dosimetry and the possibility of confounding by indication or reverse causation. The risks in adults and the risks of lung and breast cancer, the most frequent cancers in the U.S. population, remain undetermined. To provide clarity and to address important gaps in our knowledge, we propose to extend the mortality follow-up of the 63,707 CFCS patients exposed to repeated diagnostic imaging fluoroscopies in 1930-1952 by additional 30 years (for a total of 68 years, 1950-2017) as well as to conduct for the first time incidence follow-up (1969-2017). We will use CFCS's large size, the long follow-up, the individual dose assessments and the similarities in radiation exposures between fluoroscopies and CT scans to gain an unprecedented opportunity to conduct a life course examination of radiation risks. To achieve CFCS aims, we will develop a new Fluoroscopy X-rays Organ- Specific (FLUXOR) Dosimetry System and link the cohort to the Canadian Mortality and Incidence Databases covering the entire population of Canada. In addition to radiation doses to multiple organs, we will have unique data on modifiable risk factors, such as smoking, to evaluate multi-factorial etiology of cancer outcomes. Applicability of radiation risks estimated in the cohort to the U.S. general population will be further examined by pooling the CFCS data with the data from the Massachusetts Fluoroscopy Cohort Study (n=13,385). The efficient study design will provide important and previously unavailable scientific evidence on the lifespan risks of protracted radiation exposures. The research team includes experts in radiation epidemiology, biostatistics and dosimetry and is uniquely qualified to assess the appropriateness of current radiation safety standards for diagnostic imaging procedures, in particular for CT scans.