Department of Medical Imaging, University Health Network, University of Toronto, Toronto, ON, Canada.
Int J Cardiovasc Imaging. 2010 Dec;26(8):933-40. doi: 10.1007/s10554-010-9630-3. Epub 2010 Apr 27.
To compare tube current adaptation based on 3 body mass index (BMI) categories versus anterior-posterior chest diameter (APD) for radiation dose optimisation in patients undergoing dynamic volume cardiac CT. Two cardiac imaging centres participated in the study. 20 patients underwent a prospectively triggered 320-slice single beat cardiac CT using the X-ray tube current [mA] manually adjusted to the patient's BMI (group I). In 20 subsequent patients, the tube current was adapted according to the patient's APD (group II). All other parameters were kept constant. Image noise was defined as the standard deviation of attenuation values and measured using a ROI in the descending aorta. Variation in image noise was statistically compared between both patient groups. Average and standard deviation of pixel noise were 29.1 HU and 14.8 HU in group I and 28.0 HU and 4.2 HU in group II. Inter-individual variation of pixel noise was significantly lower in group II compared to group I (p < 0.0001). Tube current adaptation based on APD is superior to stepwise adaptation based on BMI for optimising radiation dose in dynamic volume cardiac CT and therefore limits unnecessary radiation dose while ensuring diagnostic image quality in patients with diverse body habitus.
为了比较基于 3 个体重指数（BMI）类别和前后径（APD）的管电流适应性，以优化行动态容积心脏 CT 的患者的辐射剂量。两个心脏成像中心参与了这项研究。20 例患者前瞻性地触发了使用 X 射线管电流[mA]的 320 层单次心跳心脏 CT，该管电流手动调整为患者的 BMI（组 I）。在随后的 20 例患者中，根据患者的 APD（组 II）来调整管电流。所有其他参数保持不变。使用降主动脉中的 ROI 定义图像噪声作为衰减值的标准偏差并进行测量。在两组患者之间对图像噪声的变化进行了统计学比较。组 I 中的平均和标准偏差像素噪声分别为 29.1 HU 和 14.8 HU，组 II 中的平均和标准偏差像素噪声分别为 28.0 HU 和 4.2 HU。与组 I 相比，组 II 中个体间像素噪声的变异性明显降低（p < 0.0001）。基于 APD 的管电流适应性优于基于 BMI 的逐步适应性，可优化动态容积心脏 CT 的辐射剂量，从而在保证不同体型患者诊断图像质量的同时限制不必要的辐射剂量。
