Fleming John S, Pitcairn Gary, Newman Stephen
Department of Nuclear Medicine, Southampton General Hospital, Southampton SO16 6YD, UK.
Phys Med Biol. 2006 Apr 7;51(7):1791-805. doi: 10.1088/0031-9155/51/7/011. Epub 2006 Mar 16.
Segmentation of the lung outline from gamma camera transmission images of the thorax is useful in attenuation correction and quantitative image analysis. This paper describes and compares two threshold-based methods of segmentation. Simulated gamma camera transmission images of test objects were used to produce a knowledge base of the variation of threshold defining the lung outline with image resolution and chest wall thickness. Two segmentation techniques based on global (GT) and context-sensitive (CST) thresholds were developed and evaluated in simulated transmission images of realistic thoraces. The segmented lung volumes were compared to the true values used in the simulation. The mean distances between segmented and true lung surface were calculated. The techniques were also applied to three real human subject transmission images. The lung volumes were estimated and the segmentations were compared visually. The CST segmentation produced significantly superior segmentations than the GT technique in the simulated data. In human subjects, the GT technique underestimated volumes by 13% compared to the CST technique. It missed areas that clearly belonged to the lungs. In conclusion, both techniques segmented the lungs with reasonable accuracy and precision. The CST approach was superior, particularly in real human subject images.
从胸部伽马相机透射图像中分割出肺部轮廓，在衰减校正和定量图像分析中很有用。本文描述并比较了两种基于阈值的分割方法。利用测试物体的模拟伽马相机透射图像，生成了一个关于定义肺部轮廓的阈值随图像分辨率和胸壁厚度变化的知识库。在逼真的胸部模拟透射图像中，开发并评估了基于全局（GT）阈值和上下文敏感（CST）阈值的两种分割技术。将分割出的肺体积与模拟中使用的真实值进行比较。计算分割的肺表面与真实肺表面之间的平均距离。这些技术还应用于三张真实人体受试者的透射图像。估计肺体积并对分割结果进行视觉比较。在模拟数据中，CST分割产生的分割结果明显优于GT技术。在人体受试者中，与CST技术相比，GT技术使体积低估了13%。它遗漏了明显属于肺部的区域。总之，两种技术都能以合理的准确性和精度分割肺部。CST方法更优，尤其是在真实人体受试者图像中。
