Impact of number of repeated scans on model observer performance for a low-contrast detection task in computed tomography
Impact of number of repeated scans on model observer performance for a low-contrast detection task in computed tomography
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DOI：
10.1117/1.jmi.3.2.023504
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发表时间：
2016-04-01
影响因子：
2.4
通讯作者：
McCollough, Cynthia
中科院分区：
文献类型：
--
作者：
Ma, Chi;Yu, Lifeng;McCollough, Cynthia
在临床计算机断层扫描（CT）中，信道化霍特林观察者（CHO）模型与人类观察者在几种基于幻象的检测/分类任务中表现出良好的相关性。大量的重复扫描被用来实现对模型模板的准确估计。本研究的目的是探讨实验和CHO模型参数如何影响重复扫描所需的最小次数。在128层CT扫描仪上以三种剂量水平扫描包含21个低对比度物体的幻影。每次扫描重复100次。对于每个实验配置，使用随机选择的扫描子集（范围从10到100），使用先前验证的CHO计算低对比度可探测性，量化为接收器工作特性曲线下的面积Az。使用100次扫描中的Az作为参考，确定了较少次数扫描的准确性。结果表明，随着辐射剂量水平的降低，物体尺寸和对比度水平的降低，通道数的增加，重复扫描的最小次数增加。总的趋势是，随着低对比度可检测性的降低，它会增加。本研究为基于任务的CHO临床CT图像质量评价实验设计提供了依据。(C) 2016年中国光学仪器工程师学会（SPIE）
Channelized Hotelling observer (CHO) models have been shown to correlate well with human observers for several phantom-based detection/classification tasks in clinical computed tomography (CT). A large number of repeated scans were used to achieve an accurate estimate of the model's template. The purpose of this study is to investigate how the experimental and CHO model parameters affect the minimum required number of repeated scans. A phantom containing 21 low-contrast objects was scanned on a 128-slice CT scanner at three dose levels. Each scan was repeated 100 times. For each experimental configuration, the low-contrast detectability, quantified as the area under receiver operating characteristic curve, Az, was calculated using a previously validated CHO with randomly selected subsets of scans, ranging from 10 to 100. Using Az from the 100 scans as the reference, the accuracy from a smaller number of scans was determined. Our results demonstrated that the minimum number of repeated scans increased when the radiation dose level decreased, object size and contrast level decreased, and the number of channels increased. As a general trend, it increased as the low-contrast detectability decreased. This study provides a basis for the experimental design of task-based image quality assessment in clinical CT using CHO. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)