Boone John M, Geraghty Estella M, Seibert J Anthony, Wootton-Gorges Sandra L
Department of Radiology, University of California Davis Medical Center, Research Imaging Center, 4701 X St, Sacramento, CA 95817, USA.
Radiology. 2003 Aug;228(2):352-60. doi: 10.1148/radiol.2282020471.
To determine size-dependent technique factors for pediatric computed tomography (CT) by using physically measured objective data.
Six phantom cylinders (10-32 cm in diameter) were scanned with a clinical multi-detector row CT scanner. CT noise was statistically characterized for CT technique factors from 80 to 140 kVp and from 10 to 300 mAs. Dose measurements were performed with each phantom. Dilute iodine and tissue contrast were determined with computer calculations validated with measured data. The dose, noise, and contrast data were computer fit, and pediatric CT technique factors (milliampere seconds) necessary to maintain the contrast-to-noise ratio (CNR) were computed.
As compared with that in a reference cylindric adult abdomen of 28 cm in diameter, CNR was maintained at a constant level in pediatric patients of 25, 20, and 15 cm in diameter, respectively, when milliampere second values of 0.557, 0.196, and 0.054 of the adult milliampere second values were used. The corresponding doses were reduced to 0.642, 0.287, and 0.090 of the 28-cm-diameter adult dose, respectively. CT techniques for examination of pediatric heads measuring 15 and 13 cm, respectively, can involve the use of milliampere second values of 0.572 and 0.366 of those used for examination of a standard 17-cm-diameter adult head.
CT technique charts for pediatric abdominal and head examinations were produced on the basis of physically measured data; use of these tables will enable pediatric radiation dose to be reduced while CNR is preserved.
通过使用物理测量的客观数据来确定儿科计算机断层扫描（CT）的尺寸相关技术参数。
使用临床多排CT扫描仪对六个体模圆柱体（直径10 - 32厘米）进行扫描。对80至140千伏峰值（kVp）以及10至300毫安秒（mAs）的CT技术参数进行CT噪声的统计学特征分析。对每个体模进行剂量测量。通过经测量数据验证的计算机计算来确定稀释碘和组织对比度。对剂量、噪声和对比度数据进行计算机拟合，并计算维持对比度噪声比（CNR）所需的儿科CT技术参数（毫安秒）。
与直径为28厘米的成人腹部参考圆柱体相比，当分别使用成人毫安秒值的0.557、0.196和0.054时，直径为25、20和15厘米的儿科患者的CNR分别保持在恒定水平。相应的剂量分别降至直径28厘米成人剂量的0.642、0.287和0.090。分别对直径为15厘米和13厘米的儿科头部进行检查的CT技术，可以使用标准直径17厘米成人头部检查所用毫安秒值的0.572和0.366。
基于物理测量数据生成了儿科腹部和头部检查的CT技术图表；使用这些表格将能够在保持CNR的同时降低儿科辐射剂量。
