Messenger Bradley, Li Dong, Nasir Khurram, Carr J Jeffrey, Blankstein Ron, Budoff Matthew J
Los Angeles Biomedical Research Institute, 1124 W Carson Street, RB2, Torrance, CA, 90502, USA.
Int J Cardiovasc Imaging. 2016 Mar;32(3):525-9. doi: 10.1007/s10554-015-0799-3. Epub 2015 Oct 29.
With the increasing use of coronary artery calcium (CAC) scoring to risk stratify asymptomatic patients for future cardiovascular events, there have been concerns raised regarding the theoretical risk of radiation exposure to this potentially large patient population. Newer CT protocols have sought to reduce radiation exposure without compromising image quality, but the reported radiation exposures in the literature remains widely variable (0.7-10.5 mSv). In this study, we report the radiation exposure of calcium scoring from our MESA cohort across several modern CT scanners with the aim of clarifying the radiation exposure of this imaging modality. To evaluate the mean effective doses of radiation, using dose length product, utilized for coronary artery calcium scoring in the MESA cohort, in an effort to understand estimated population quantity effective dose using individual measurements of scanner radiation output using current CT scanners. We reviewed effective dose in milliSieverts (mSv) for 3442 participants from the MESA cohort undergoing coronary artery calcium scoring, divided over six sites with four different modern CT scanners (Siemens64, Siemens Somatom Definition, GE64, and Toshiba 320). For effective dose calculation (milliSieverts, mSv), we multiplied the dose length product by conversion factor k (0.014). The mean effective dose amongst all participants was 1.05 mSv, a median dose of 0.95 mSV. The mean effective dose ranged from 0.74 to 1.26 across the six centers involved with the MESA cohort. The Siemens Somatom Definition scanner had effective dose of 0.53 (n = 123), Siemens 64 with 0.97 (n = 1684), GE 64 with 1.16 (n = 1219), and Toshiba 320 with 1.26 mSv (n = 416). Subgroup analysis by BMI, age, and gender showed no variability between scanners, gender, ages 45-74 years old, or BMI less than 30 kg/m(2). Subjects over age 75 yo had a mean effective dose of 1.29 ± 0.31 mSv, while the <75 yo subgroup was 0.78 ± 0.09 mSv (p < 0.05). Effective doses in subjects with BMI > 40 kg/m(2) was significantly greater than other subgroups, with mean dose of 1.47 ± 0.51 mSv (p < 0.01). Using contemporary CT scanners and protocols, the effective dose for coronary artery calcium is approximately 1 mSv, an estimate which is consistently lower than previously reported for CAC scanning, regardless of age, gender, and body mass index.
随着冠状动脉钙化（CAC）评分越来越多地用于对无症状患者未来心血管事件进行风险分层，人们对这一潜在庞大患者群体受到辐射暴露的理论风险表示担忧。更新的CT方案试图在不影响图像质量的情况下减少辐射暴露，但文献中报道的辐射暴露量仍有很大差异（0.7 - 10.5 mSv）。在本研究中，我们报告了来自多民族动脉粥样硬化研究（MESA）队列中通过几种现代CT扫描仪进行钙化评分时的辐射暴露情况，目的是阐明这种成像方式的辐射暴露情况。为了评估使用剂量长度乘积用于MESA队列中冠状动脉钙化评分的平均有效辐射剂量，以便通过使用当前CT扫描仪对扫描仪辐射输出进行个体测量来了解估计的人群有效剂量。我们回顾了MESA队列中3442名接受冠状动脉钙化评分的参与者以毫西弗（mSv）为单位的有效剂量，这些参与者分布在六个地点，使用了四种不同的现代CT扫描仪（西门子64排、西门子Definition双源CT、GE 64排和东芝320排）。对于有效剂量计算（毫西弗，mSv），我们将剂量长度乘积乘以转换因子k（0.014）。所有参与者的平均有效剂量为1.05 mSv，中位数剂量为0.95 mSv。在参与MESA队列的六个中心中，平均有效剂量范围为0.74至1.26 mSv。西门子Definition双源CT扫描仪的有效剂量为0.53（n = 123），西门子64排为0.97（n = 1684），GE 64排为1.16（n = 1219），东芝320排为1.26 mSv（n = 416）。按体重指数（BMI）、年龄和性别进行的亚组分析显示，扫描仪、性别、45 - 74岁年龄组或BMI小于30 kg/m²之间没有差异。75岁以上的受试者平均有效剂量为1.29 ± 0.31 mSv，而75岁以下亚组为0.78 ± 0.09 mSv（p < 0.05）。BMI > 40 kg/m²的受试者的有效剂量显著高于其他亚组，平均剂量为1.47 ± 0.51 mSv（p < 0.01）。使用当代CT扫描仪和方案，冠状动脉钙化的有效剂量约为1 mSv，这一估计值始终低于先前报道的CAC扫描剂量，无论年龄、性别和体重指数如何。
