Department of Imaging, Nagoya Kyoritsu Hospital, Nagoya, Aichi, Japan.
Department of Radiological Technology, Faculty of Health Sciences, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
J Appl Clin Med Phys. 2021 Feb;22(2):178-184. doi: 10.1002/acm2.13171. Epub 2021 Jan 15.
This study aimed to compare the dose and noise level of four tube voltages in abdominal computerized tomography (CT) examinations in different abdominal circumference sizes of pregnant women. Fetal radiation doses were measured with two anthropomorphic pregnant phantoms and real-time dosimeters of photoluminescence sensors using four tube voltages for abdominal CT. The noise level was measured at the abdomen of two anthropomorphic pregnant phantoms. In the large pregnant phantom, the mean fetal doses performed using 120 and 135 kV were statistically significantly lower than the lower tube voltages (P < 0.05). In the small pregnant phantom, the mean fetal dose performed by 100, 120, and 135 kV was significantly lower than the lowest tube voltage tested (P < 0.05). The ratios of the peripheral mean dose to the centric mean dose showed that the ratios of 80 kV were the highest and those for 135 kV were the lowest in both pregnant phantoms. The ratios of the peripheral mean dose to the centric mean dose decreased as the tube voltage increased. Compared with low tube voltages, high tube voltages such as 120 and 135 kV could reduce radiation doses to the fetus without compromising the image uniformity in abdominal CT examinations during pregnancy. On low tube voltage protocols, the dose near the maternal skin surface may be increased in large pregnant women because of reduced penetration of the x rays.
本研究旨在比较四种管电压在不同腹围大小孕妇腹部计算机断层扫描（CT）检查中的剂量和噪声水平。使用两种人体孕妇模拟体和光致发光传感器的实时剂量计，对腹部 CT 检查中的四个管电压进行胎儿剂量测量。在两个人体孕妇模拟体的腹部测量噪声水平。在大孕妇模拟体中，使用 120 和 135 kV 进行的平均胎儿剂量明显低于较低的管电压（P < 0.05）。在小孕妇模拟体中，100、120 和 135 kV 进行的平均胎儿剂量明显低于测试的最低管电压（P < 0.05）。外周平均剂量与中心平均剂量的比值表明，在两个孕妇模拟体中，80 kV 的比值最高，而 135 kV 的比值最低。随着管电压的增加，外周平均剂量与中心平均剂量的比值减小。与低管电压相比，高管电压（如 120 和 135 kV）可以在不影响妊娠腹部 CT 检查图像均匀性的情况下降低胎儿的辐射剂量。在低管电压方案中，由于 X 射线的穿透减少，大孕妇的母体皮肤表面附近的剂量可能会增加。
