Monash Cardiovascular Research Center, MonashHEART, Monash Medical Center, 246 Clayton Road, Clayton 3168, Australia.
J Cardiovasc Comput Tomogr. 2013 May-Jun;7(3):157-66. doi: 10.1016/j.jcct.2013.05.002. Epub 2013 May 31.
Minimization of radiation exposure remains an important subject that occurs in parallel with advances in scanner technology.
We report our experience of evolving radiation dose and its determinants after the introduction of 320-multidetector row cardiac CT within a single tertiary cardiology referral service.
Four cohorts of consecutive patients (total 525 scans), who underwent cardiac CT at defined time points as early as 2008, are described. These include a cohort just after scanner installation, after 2 upgrades of the operating system, and after introduction of an adaptive iterative image reconstruction algorithm. The proportions of nondiagnostic coronary artery segments and studies with nondiagnostic segments were compared between cohorts.
Significant reductions were observed in median radiation doses in all cohorts compared with the initial cohort (P < .001). Median dose-length product fell from 944 mGy · cm (interquartile range [IQR], 567.3-1426.5 mGy · cm) to 156 mGy · cm (IQR, 99.2-265.0 mGy · cm). Although the proportion of prospectively triggered scans has increased, reductions in radiation dose have occurred independently of distribution of scan formats. In multiple regression that combined all groups, determinants of dose-length product were tube output, the number of cardiac cycles scanned, tube voltage, scan length, scan format, body mass index, phase width, and heart rate (adjusted R(2) = 0.85, P < .001). The proportion of nondiagnostic coronary artery segments was slightly increased in group 4 (2.9%; P < .01).
While maintaining diagnostic quality in 320-multidetector row cardiac CT, the radiation dose has decreased substantially because of a combination of dose-reduction protocols and technical improvements. Continued minimization of radiation dose will increase the potential for cardiac CT to expand as a cardiac imaging modality.
在扫描仪技术不断进步的同时，降低辐射暴露仍然是一个重要的课题。
我们报告在单一的三级心脏病学转介服务中引入 320 层多排 CT 后，辐射剂量及其决定因素的演变经验。
描述了在特定时间点进行心脏 CT 检查的连续 4 组患者（共 525 例）。这些组包括扫描仪安装后的第一组，操作系统升级后的 2 组，以及引入自适应迭代图像重建算法后的 1 组。比较了各组之间非诊断性冠状动脉节段的比例和非诊断性节段的研究。
与初始组相比，所有组的中位数辐射剂量均显著降低（P<0.001）。中位数剂量长度乘积从 944 mGy·cm（四分位距[IQR]，567.3-1426.5 mGy·cm）降至 156 mGy·cm（IQR，99.2-265.0 mGy·cm）。尽管前瞻性触发扫描的比例有所增加，但辐射剂量的降低与扫描格式的分布无关。在综合所有组的多元回归中，剂量长度乘积的决定因素是管输出、扫描的心脏周期数、管电压、扫描长度、扫描格式、体重指数、相位宽度和心率（调整 R²=0.85，P<0.001）。第 4 组非诊断性冠状动脉节段的比例略有增加（2.9%；P<0.01）。
在 320 层多排 CT 中维持诊断质量的同时，由于剂量减少方案和技术改进的结合，辐射剂量已大大降低。持续降低辐射剂量将增加心脏 CT 作为一种心脏成像方式扩展的潜力。
