Department of Medical Physics, Faculty of Medicine, University of Crete, Crete, Greece.
Invest Radiol. 2012 Aug;47(8):451-6. doi: 10.1097/RLI.0b013e318250a58c.
The aim of this study was to determine the radiation burden and the lifetime attributable risk (LAR) of radiation-induced cancer in patients undergoing screening 256-slice computed tomography colonography (CTC) and compare CTC-related radiogenic risks to corresponding nominal lifetime intrinsic risk of cancer.
A Monte Carlo simulation software dedicated for computed tomography (CT) dosimetry was used to determine absorbed doses to primarily exposed radiosensitive organs of 31 women and 29 men subjected to screening CTC on a 256-slice CT scanner. Effective dose was estimated from (a) organ dose data and (b) dose-length product. Organ-specific and total LARs of cancer were estimated using published risk factors. Cumulative LARs from repeated CTC studies on individuals participating in a colorectal cancer screening program were compared with corresponding lifetime intrinsic risks.
The mean organ dose-derived effective dose was estimated to be 2.92 and 2.61 mSv for female and male individuals, respectively. The dose-length product method was found to overestimate effective dose from CTC by 26% and 13% in female and male individuals, respectively. Compared with previously published results for 64-slice CT scanners, 256-slice CTC was found to be associated with up to 45% less radiation burden. The cumulative LAR of radiation-induced cancer from repeated quinquennial screening CTC studies between the ages of 50 and 80 years was estimated to increase the lifetime intrinsic risk of cancer by less than 0.2%.
The level of patient radiation burden and theoretical radiogenic cancer risks associated with screening CTC performed using modern low-dose protocols and techniques may not justify disapproval of CTC as a mass screening tool.
本研究旨在确定接受 256 层螺旋 CT 结肠成像（CTC）筛查的患者的辐射负担和归因于辐射的癌症终生风险（LAR），并将 CTC 相关的放射性风险与相应的癌症固有终生风险进行比较。
使用专门用于 CT 剂量学的蒙特卡罗模拟软件，对 31 名女性和 29 名男性进行 256 层 CT 扫描仪筛查 CTC 时主要暴露的敏感器官的吸收剂量进行了测定。有效剂量是根据（a）器官剂量数据和（b）剂量长度乘积来估算的。使用发表的风险因素估算了器官特异性和总癌症 LAR。将参与结直肠癌筛查计划的个体重复 CTC 研究的累积 LAR 与相应的终生固有风险进行了比较。
估计女性和男性个体的器官剂量衍生有效剂量的平均值分别为 2.92 和 2.61 mSv。发现剂量长度乘积法高估了女性和男性个体的 CTC 有效剂量，分别为 26%和 13%。与 64 层 CT 扫描仪的先前发表结果相比，256 层 CTC 与 45%的辐射负担减少有关。从 50 岁至 80 岁之间进行的重复五年一次的筛查 CTC 研究的累积辐射诱发癌症的 LAR 估计会使终生固有癌症风险增加不到 0.2%。
使用现代低剂量方案和技术进行的筛查 CTC 所带来的患者辐射负担水平和理论放射性癌症风险可能不足以反对 CTC 作为一种大规模筛查工具。
