Sousa Pedro Jerónimo, Gonçalves Pedro Araújo, Marques Hugo, Raposo Luís, Calé Rita, Brito João, Gaspar Augusto, Machado Francisco Pereira, Roquette José
Centro Cardiovascular, Hospital da Luz, Lisboa, Portugal.
Rev Port Cardiol. 2010 Nov;29(11):1655-65.
Cardiac CT provides noninvasive information on cardiac anatomy, particularly in coronary artery disease. However, exposure to radiation has been identified as a limitation of this exam. The aim of this study was to evaluate variations in radiation dose over time and to identify variables associated with use of higher radiation doses.
A prospective registry of 643 patients who underwent 64-slice dual source cardiac CT scan (Dual source CT--Somaton Definition, Siemens-Medical) during 2007 and 2008 was analyzed.
The sample was divided into quartiles according to the chronological order of the exams. There was a progressive reduction in median radiation dose in the quartiles analyzed (Q1: 8.9 [5.9-14.1], Q2: 6.6 [5.5-10.7], Q3: 6.4 [5.3-8.7], Q4: 6.1 [5.2-7.9] mSv), significant when the first quartile was compared with the others (p < 0.05). Along with this reduction, was a progressive increase in the use of a tube voltage of 100 kV (p < 0.001). Predictors of a higher radiation dose were higher body mass index, previous cardiac surgery, atrial fibrillation during acquisition, longer acquisition time and use of a tube voltage of 120 kV. When one or more of these variables were present (one third of the population), the radiation dose was significant higher (12.1 [9.5-14.8] vs. 5.7 [5.0-6.7] mSv, p < 0.001).
心脏CT能提供有关心脏解剖结构的无创信息，尤其是在冠状动脉疾病方面。然而，辐射暴露已被视为这项检查的一个局限性。本研究的目的是评估辐射剂量随时间的变化，并确定与使用较高辐射剂量相关的变量。
对2007年至2008年期间接受64层双源心脏CT扫描（双源CT——西门子医疗公司的 Somaton Definition）的643例患者的前瞻性登记资料进行分析。
根据检查的时间顺序将样本分为四分位数。在所分析的四分位数中，中位辐射剂量呈逐渐降低趋势（第一四分位数：8.9 [5.9 - 14.1]，第二四分位数：6.6 [5.5 - 10.7]，第三四分位数：6.4 [5.3 - 8.7]，第四四分位数：6.1 [5.2 - 7.9] mSv），当将第一四分位数与其他四分位数进行比较时差异有统计学意义（p < 0.05）。随着这种降低，使用100 kV管电压的比例逐渐增加（p < 0.001）。较高辐射剂量的预测因素包括较高的体重指数、既往心脏手术史、采集过程中的心房颤动、较长的采集时间以及使用120 kV的管电压。当存在一个或多个这些变量时（占总体的三分之一），辐射剂量显著更高（12.1 [9.5 - 14.8] 对比 5.7 [5.0 - 6.7] mSv，p < 0.001）。
