Comparison of z-axis automatic tube current modulation technique with fixed tube current CT scanning of abdomen and pelvis
Comparison of z-axis automatic tube current modulation technique with fixed tube current CT scanning of abdomen and pelvis
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DOI：
10.1148/radiol.2322031304
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发表时间：
2004-08-01
期刊：
影响因子：
19.7
通讯作者：
Saini, S
中科院分区：
文献类型：
--
作者：
Kalra, MK;Maher, MM;Saini, S
目得：比较采用自动管电流调制的z轴调制技术和手动选择固定管电流进行的腹部和骨盆16节段多探测器行计算机断层扫描（CT）检查的图像质量、诊断可接受性和辐射暴露。（平均年龄，60岁;年龄范围，19-84岁;男女比例，35：27）使用16节段多探测器行扫描仪和z轴调制技术（10.5-12.0-HU噪声指数，10-380 mA）进行腹部和骨盆的随访CT。扫描参数包括140 kVp、0.5-1.0秒机架旋转时间、0.938：1射束间距和5 mm重建切片厚度。对于每个受试者，将使用z轴调制获得的图像与使用固定管电流（200-300 mA）和其他参数相同获得的先前图像进行比较。由两名亚专科放射科医生使用五分量表（1，不可接受; 3，可接受; 5，极好）在五个水平（膈上肝、肝门、右肾门、髂嵴和髋臼上缘）比较图像的噪声和诊断可接受性。记录在这些节段采集所用的管电流和机架旋转时间。数据进行了分析，参数和非参数统计tests.Results：虽然没有发现显着差异（P = 0.34），与z轴调制在肝脏上部（隔膜）和髋臼的水平获得的图像有较高的噪声和较低的诊断质量，与固定管电流获得的图像相比。与固定管电流相比，Z轴调制导致62次检查中有54次（87%）管电流-时间乘积降低（平均降低，71.2 mAs），8例（13%）升高（平均增加，17.0 mAs）。与手动选择固定管电流相比，z轴自动管电流调制导致管电流-时间乘积降低，腹部和骨盆CT的图像噪声和诊断可接受性相似。(C)RSNA，2004年。
PURPOSE: To compare image quality, diagnostic acceptability, and radiation exposure associated with 16-section multi-detector row computed tomographic (CT) examinations of abdomen and pelvis performed with z-axis modulation technique of automatic tube current modulation and with manual selection of fixed tube current.MATERIALS AND METHODS: Sixty-two consecutive subjects (mean age, 60 years; age range, 19-84 years; male-to-female ratio, 35:27) underwent follow-up CT of abdomen and pelvis with use of a 16-section multi-detector row scanner and z-axis modulation technique (10.5-12.0-HU noise index, 10-380 mA). Scanning parameters included 140 kVp, 0.5-1.0-second gantry rotation time, 0.938:1 beam pitch, and 5-mm reconstructed section thickness. For each subject, images obtained with z-axis modulation were compared with previous images obtained with fixed tube current (200-300 mA) and with other parameters identical. Images were compared for noise and diagnostic acceptability by two subspecialty radiologists using a five-point scale (1, unacceptable; 3, acceptable; 5, excellent) at five levels: upper liver at diaphragm, porta hepatis, right kidney hilum, iliac crest, and upper margin of acetabulum. Tube current and gantry rotation time used for acquisitions at these levels were recorded. Data were analyzed with parametric and nonparametric statistical tests.RESULTS: Although no significant differences were found (P = .34), images acquired with z-axis modulation at the levels of the upper liver (diaphragm) and acetabulum had a higher noise and lower diagnostic quality, compared with images acquired with fixed tube current. Compared with fixed tube current, z-axis modulation resulted in tube current-time product reduction in 54 (87%) of 62 examinations (mean reduction, 71.2 mAs) and increase in eight (13%) (mean increase, 17.0 mAs).CONCLUSION: Compared with manually selected fixed tube current, z-axis automatic tube current modulation resulted in reduced tube current-time product and similar image noise and diagnostic acceptability at CT of abdomen and pelvis.(C) RSNA, 2004.