Impact of miscentering on patient dose and image noise in x-ray CT imaging: Phantom and clinical studies
Impact of miscentering on patient dose and image noise in x-ray CT imaging: Phantom and clinical studies
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DOI：
10.1016/j.ejmp.2011.06.002
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发表时间：
2012-07-01
影响因子：
3.4
通讯作者：
Zaidi, H.
中科院分区：
文献类型：
--
作者：
Habibzadeh, M. A.;Ay, M. R.;Zaidi, H.
如果被扫描的物体在扫描仪的视场中处于正确的中心位置，则在X射线CT中蝴蝶结滤镜的操作是正确的。否则，传递给患者的剂量和图像噪声将偏离最佳设置。我们研究了三台商用CT扫描仪上偏心对图像噪声和表面剂量的影响。在每个扫描仪上扫描了6个不同大小和材料的圆柱体模。模体分别位于扫描仪视场等中心下方0、2、4和6厘米处。建立了表面剂量和噪声随偏心幅度和体模尺寸变化的回归模型。使用计算的回归模型对480名患者进行评估，以估计患者偏心对7个成像中心的图像噪声和患者表面剂量的影响。在层析CT扫描仪上，错位2 cm、4 cm和6 cm时，CTDI-32体模的表面剂量增加最大值分别为13.5%、33.3%和51.1%。对患者的扫描分析显示，偏心平均比等中心低2.2厘米。患者剂量和图像噪声分别平均增加23%和7%。患者偏心的最大偏差来自于使用相同扫描仪的成像中心的比较，为1.6厘米。患者偏心可能会显著增加表面剂量和图像噪声。因此，强烈鼓励技术人员更多地关注以患者为中心。(C)2011年意大利菲西卡医学协会。爱思唯尔有限公司出版。保留所有权利。
The operation of the bowtie filter in x-ray CT is correct if the object being scanned is properly centered in the scanner's field-of-view. Otherwise, the dose delivered to the patient and image noise will deviate from optimal setting. We investigate the effect of miscentering on image noise and surface dose on three commercial CT scanners. Six cylindrical phantoms with different size and material were scanned on each scanner. The phantoms were positioned at 0, 2, 4 and 6 cm below the isocenter of the scanner's field-of-view. Regression models of surface dose and noise were produced as a function of miscentering magnitude and phantom's size. 480 patients were assessed using the calculated regression models to estimate the influence of patient miscentering on image noise and patient surface dose in seven imaging centers. For the 64-slice CT scanner, the maximum increase of surface dose using the CTDI-32 phantom was 13.5%, 33.3% and 51.1% for miscenterings of 2,4 and 6 cm, respectively. The analysis of patients' scout scans showed miscentering of 2.2 cm in average below the isocenter. An average increase of 23% and 7% was observed for patient dose and image noise, respectively. The maximum variation in patient miscentering derived from the comparison of imaging centers using the same scanner was 1.6 cm. Patient miscentering may substantially increase surface dose and image noise. Therefore, technologists are strongly encouraged to pay greater attention to patient centering. (C) 2011 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.