Itoh S, Koyama S, Ikeda M, Ozaki M, Sawaki A, Iwano S, Ishigaki T
Department of Radiology, Nagoya University School of Medicine, Japan.
J Thorac Imaging. 2001 Apr;16(2):81-8. doi: 10.1097/00005382-200104000-00003.
A new aluminum filter, 5.8 mm thick at the center, was designed. The effective energy, exposure dose, absorbed dose, and noise were measured by using low-dose technique, very low-dose technique with a conventional filter, and very low-dose technique with a new filter on a chest phantom. Accuracy of very low-dose computed tomography (CT) with a new filter was compared against standard helical CT in 40 patients and against chest radiography in 35 patients. Effective energies were 42.6 keV and 51.6 keV at a conventional filter and the new filter, respectively. Compared against 20mA with a conventional filter, exposure dose was reduced by 17%, and absorbed dose was equivalent, at 30 mA with the new filter. Noise was improved by 9%. Compared with standard helical CT, the sensitivity, specificity, and accuracy of very-low-dose helical CT were 100%, 88%, and 95%, respectively. Very-low-dose helical CT was found to be significantly superior to chest radiography in the detection of lung cancers. Using a smaller tube current and an appropriate filter allows a further reduction in radiation dose in helical CT for lung cancer screening.
设计了一种新型铝滤过器，其中心厚度为5.8毫米。采用低剂量技术、使用传统滤过器的极低剂量技术以及使用新型滤过器的极低剂量技术，在胸部模体上测量了有效能量、照射剂量、吸收剂量和噪声。将40例患者使用新型滤过器的极低剂量计算机断层扫描（CT）的准确性与标准螺旋CT进行比较，并与35例患者的胸部X线摄影进行比较。传统滤过器和新型滤过器的有效能量分别为42.6 keV和51.6 keV。与使用传统滤过器的20 mA相比，使用新型滤过器在30 mA时照射剂量降低了17%，吸收剂量相当，噪声改善了9%。与标准螺旋CT相比，极低剂量螺旋CT的敏感性、特异性和准确性分别为100%、88%和95%。发现极低剂量螺旋CT在肺癌检测方面明显优于胸部X线摄影。使用较小的管电流和合适的滤过器可进一步降低用于肺癌筛查的螺旋CT的辐射剂量。
