Matsunaga Yuta, Kawaguchi Ai, Kobayashi Masanao, Suzuki Shoichi, Asada Yasuki, Ito Kiyoshi, Chida Koichi
Graduate school of Medicine, Tohoku University, Aoba-ku, Sendai, Japan.
Department of Imaging, Nagoya Kyoritsu Hospital, Nagoya, Japan.
J Appl Clin Med Phys. 2017 Sep;18(5):330-335. doi: 10.1002/acm2.12154. Epub 2017 Aug 11.
This study aimed to examine the relationship between fetal dose and the dose-length product, and to evaluate the impact of the number of rotations on the fetal doses and maternal effective doses using a 320-row multidetector computed tomography unit in a wide-volume mode. The radiation doses for the pregnant woman and the fetus were estimated using ImPACT CT Patient Dosimetry Calculator software for scan lengths ranging from 176 to 352 mm, using a 320-row unit in a wide-volume mode and an 80-row unit in a helical scanning mode. In the 320-row unit, the fetal doses in all scan lengths ranged from 3.51 to 6.52 mGy; the maternal effective doses in all scan lengths ranged from 1.05 to 2.35 mSv. In the 80-row unit, the fetal doses in all scan lengths ranged from 2.50 to 3.30 mGy; the maternal effective doses in all scan lengths ranged from 0.83 to 1.68 mSv. The estimated conversion factors from the dose-length product (mGy・cm) to fetal doses (mGy) for the 320-row unit in wide-volume mode and the 80-row unit in helical scanning mode were 0.06 and 0.05 (cm ) respectively. While using a 320-row MDCT unit in a wide-volume mode, operators must take into account the number of rotations, the beam width as automatically determined by the scanner, the placement of overlap between volumetric sections, and the ratio of overlapping volumetric sections.
本研究旨在探讨胎儿剂量与剂量长度乘积之间的关系，并使用320排多探测器计算机断层扫描设备在宽体模式下评估旋转次数对胎儿剂量和母体有效剂量的影响。使用ImPACT CT患者剂量计算软件，对扫描长度在176至352毫米之间的孕妇和胎儿的辐射剂量进行估算，扫描采用320排设备的宽体模式以及80排设备的螺旋扫描模式。在320排设备中，所有扫描长度下的胎儿剂量范围为3.51至6.52毫戈瑞；所有扫描长度下的母体有效剂量范围为1.05至2.35毫希沃特。在80排设备中，所有扫描长度下的胎儿剂量范围为2.50至3.30毫戈瑞；所有扫描长度下的母体有效剂量范围为0.83至1.68毫希沃特。320排设备宽体模式和80排设备螺旋扫描模式下从剂量长度乘积（毫戈瑞·厘米）到胎儿剂量（毫戈瑞）的估算转换系数分别为0.06和0.05（厘米）。当使用320排MDCT设备的宽体模式时，操作人员必须考虑旋转次数、扫描仪自动确定的束宽、容积切片之间的重叠位置以及重叠容积切片的比例。
