Theoretical analysis of diagnostic process of medical image and optimization of CRT image processing

本研究的目的在于明确在ORT观象台解读胸部ct影像时，影像诊断过程中肺部细微异常表现特征与观察者诊断能力的关系，优化各种影像处理方式，最终建立CRT诊断中最有效的影像处理方式。在ORT监视器上对细微肺部异常的解释结果显示，高频增强不一定是有益的，因为正常动脉经常模仿异常的间质阴影。通常低频增强处理优于高频增强处理。此外，尽管在传统胶片图像上可以检测到，但由于图像处理不当导致图像模糊，在软拷贝图像上可能会遗漏细微的磨砂玻璃发现。图像处理的效果取决于异常的类型和特征。在对图像处理效果的评价中也发现了观察者间的差异。CRT显示器的成像诊断具有图像处理自由的优点。然而，从传统胶片图像发展而来的诊断标准和诊断过程，并不一定要直接应用于软拷贝图像。尤其是高频增强处理，往往会导致胸部图像的过度诊断或诊断不足。

The purpose of this research is to clarify the relationship between the characteristic of subtle abnormal pulmonary findings and observer's diagnostic performance in the imagediagnostic process when CR(computed radiograph) chest image is interpreted on a ORT viewing station, to optimize various kinds of image processing, and finally to establish the most effective image-processing on CRT diagnosis. The result of the interpretation of subtle pulmonary abnormalities on the ORT monitor showed that high frequency enhancement, was not necessary beneficial because the normal arteries often mimicked the abnormal interstitial shadows. Generally low frequency enhancement processing was better than high frequency enhancement In addition, the presence of subtle ground glass finding may be missed on a soft-copy image due to inadequate image processing resulting in blurred image, although detected on the conventional film image. The effect of image processing differs depending on the type and characteristic of abnormalities.Interobserver's difference was also found in the evaluation of the effect of image processing. Imaging diagnosis on CRT monitor has a merit of freely available image processing. However, diagnostic criterion and its process developed from conventional screen-film image are not necessary applied directly to-soft copy image. Especially, high frequency enhancement, processing often induces over- or underdiagnosis of chest image.