Detectability of low-contrast features in computed tomography.
Detectability of low-contrast features in computed tomography.
复制标题
计算机断层扫描中低对比度特征的可检测性。
DOI：
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发表时间：
1984
影响因子：
3.5
通讯作者：
R. C. Warren
中科院分区：
文献类型：
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作者：
R. C. Warren
利用信号检测实验研究了计算机断层扫描中影响低对比度特征可检测性的因素。发现均匀噪声场中圆形物体的可检测性随着窗口宽度的减小而增加。随着观察距离的增加，可探测性增加到最大值，然后下降;发现最佳观察距离随着窗口宽度的减小而增加。可检测性是独立的窗口电平和图像亮度，在研究的值的范围内。以经验传递特性为系统描述符，采用模式识别的最优匹配滤波器模型，建立了CT显示系统与人眼视觉系统的数学模型。当考虑到视觉对比敏感度函数和观察者内部噪声的影响时，理论信噪比与实验数据定性一致。定量差异表明，视觉匹配滤波器处理是次优的，或者使用的对比敏感度函数作为空间滤波器是近似有效的。与视觉系统特征相比，显示系统的特征不显著。建议对CT显示配置进行修改，以最大限度地提高显示系统与放射科医师视觉系统之间的信息传输。
Factors affecting low-contrast feature detectability in computed tomography have been investigated using signal detection experiments. Detectability of a circular object in a uniform noise field was found to increase with decreasing window width. With increasing viewing distance, detectability increased to a maximum before decreasing; the optimal viewing distance was found to increase with decreasing window width. Detectability was independent of window level and image luminance, over the range of values studied. A mathematical model of the CT display system and the human visual system was constructed, using empirical transfer characteristics as system descriptors and an optimal matched filter model of pattern recognition. Theoretical signal-to-noise ratios were in qualitative agreement with the experimental data when account was taken of the visual contrast sensitivity function and the effect of noise internal to the observer. Quantitative discrepancies suggest either that visual matched filter processing is sub-optimal, or that use of the contrast sensitivity function as a spatial filter is only approximately valid. Compared with the visual system characteristics, those of the display system were insignificant. Modifications to CT display configurations are suggested in order to maximise information transfer between the display system and the visual system of the radiologist.