CT发展史之CT图像的处理与评估

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                    <section data-role="paragraph" data-color="rgb(182, 228, 253)" data-custom="rgb(182, 228, 253)"><section><section><section><section powered-by="gulangu"><section><section><section><section powered-by="gulangu"><section><section><section><section powered-by="gulangu"><section><section><section><section powered-by="gulangu"><section><section><section><section><p><p><img src="image/20201014/86b79d371e9862b01189f0252a03b2cd_1.png" /></p></p></section><section><section><span><strong></strong></span></section><p><span>医疗器械媒体报道先锋</span></p><p><span>分享专业医疗器械知识</span></p></section><section><section><section>关注</section></section></section></section></section></section></section></section></section></section></section></section></section></section></section></section></section></section></section></section></section></section></section><p><strong><span>来源：</span></strong></p><p><br  /></p><section><section powered-by="gulangu"><section><section><p>CT图像是以数字矩阵的形式存在的，与传统的模拟放射照片不同。它们可以涌过计算机算法应用和电子技术，对已获取的数字图像矩阵进行有针对性地灵活加工处理，使图像能够清晰显示，方便被识别、辨认。<span>搜集整理了几种常用的图像处理和评估技术。</span></p><p><span><br  /></span></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><strong>窗口技术</strong></p></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><p>窗口技术指CT机控制、调节某段范围内窗宽、窗位的技术，即把人体欲被观测组织的CT值范围对应为放大的灰度范围，作为窗口。超其上限设定为全白，超其下限设定为全黑。这就增强了局部范围内不同CT值之间的对比度。对应窗口上下限灰度范围的CT值跨度称为窗宽，其中心值称为窗位。</p><p><br  /></p><p>人体不同的病变组织需设定的窗口范围也不同，为了加速窗宽和窗位的搜寻和确定，CT机设计和设置了许多方法，如可设窗中窗以迅速捕捉到CT值范围不同的病变组织，还可在窗宽范围内重点强调某一范围内的CT值并给出一明显的标记等。</p></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><strong>双窗技术</strong></p></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><p>除了常规窗的设置和显示外，可以把两种CT值相差较大的组织在同一窗口中显示，这种显示方法称为“双窗”。双窗是一种最普通的非线性窗，在大多数CT机上都已预设了该功能。它的优点是能把两种不同类型的软组织同时在一张图片上显示，便于综合对比，在肺部图像的诊断中使用得较多。双窗设置的优点是显而易见的，但它也有缺点。双窗技术在两种窗设置的移动区域会形成一个边缘效应，对某些疾病的诊断可能会造成一些影响，故只能仅供参考。</p></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><img src="image/20201014/931dfe4c8acb535772b18246ac45baf7_2.png" /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p>纵隔窗</p></section></section></section></section></section></section></section><section><section powered-by="gulangu"><section><section><p><img src="image/20201014/3574599dd5c179937f94b2ae3b6861e1_3.png" /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p>双窗</p></section></section></section></section></section></section></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><img src="image/20201014/4b57abb04e7850116eaaa2fc44cee710_4.png" /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p>肺窗</p></section></section></section></section></section></section></section><section><section powered-by="gulangu"><section><section><p><img src="image/20201014/cd34b574846c3d44c6ed8f670a498239_5.png" /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p>双窗的设置和显示</p></section></section></section></section></section></section></section></section></section></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><strong>sigma窗</strong></p></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><p>sigma窗也属于一种非线性窗。它的设置一般需通过CT所附的软件来完成。有曲线法和数据转换法两种设置方法。</p><p><br  /></p><p>曲线法sigma窗的设置是将原窗宽的下限提高到窗宽的上限，而将窗位所对应的灰阶降低至最低灰阶，从而形成了sigma窗。</p><p><br  /></p><p>数据转换法设置非线性窗是以曲线法为基础的。首先确定非线性窗曲线的形态，然后依经验选择适合大多数病人实际情况的窗宽、窗位，根据它们的灰阶分布转换成数据。采用数据法得到的是一条固定的额sigma窗曲线，有时不能完全适应观察的需要，这是数据转换法最大的的缺点。</p><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><strong>感兴趣区域（ROI）的选择和测量<br  /></strong></p></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><p>作为CT图像处理和评估中最基本的功能之一，CT提供了感兴趣区域（ROI）的选择和测量功能。感兴趣区CT值测量其范围的大小一般可根据病灶的大小自定义，形状由用户自选，通常有圆形、椭圆形、矩形、多边形圆，测量数从一至数个不等。 其测得的CT值是所定范围内的平均值，并标有标准误差供作参考。 对CT图像的性能评估起很大作用。</p><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201014/fa1def6a2b3b1720a42fbc1f552568ba_6.png" /></p></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p><p>直方图常用来标志组织的特性。直方图显示为一条曲线，重叠在图像上，其横坐标是CT值，纵坐标是具有该CT值的（感兴趣区域内的）像素数目。</p><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><img src="image/20201014/77c934d9b9bed7dee25749723774d946_7.png" /></p></section></section></section><section powered-by="gulangu"><section><section><p><em>1</em></p></section></section></section></section><section><section powered-by="gulangu"><section><section><p><img src="image/20201014/a8687c93cb97acbcae83f3e698591b24_8.png" /></p></section></section></section><section powered-by="gulangu"><section><section><p><em>2</em></p></section></section></section></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><strong>任意断面成像</strong></p></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><p>有时，使用一个不同于扫描平面的另外平面，更有益于观察某个病理部位或解剖部位。这时可以从一系列相继的扫描断面中重新构造出任意一个垂直于扫描平面的平面来。如果该平面是上下方向叫做横断面。如果该平面是前后方向的叫矢状面。如果该平面是左右方向的则叫冠状面。<br  /></p><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><img src="image/20201014/1a1b6bece026021ef04232ab7a6ceac0_9.png" /></p></section></section></section><section powered-by="gulangu"><section><section><section><section><p>横断面</p></section></section></section></section></section></section><section><section powered-by="gulangu"><section><section><p><img src="image/20201014/ec0bb63ba95ab7e68d039045057999b1_10.png" /></p></section></section></section><section powered-by="gulangu"><section><section><section><section><p>矢状面</p></section></section></section></section></section></section><section><section powered-by="gulangu"><section><section><p><img src="image/20201014/7bf42ff2ac6ed30a4f0f9876bf6020cd_11.png" /></p></section></section></section><section powered-by="gulangu"><section><section><section><section><p>冠状面</p></section></section></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section></section><p><strong><span>本由整理/原创，转载请注明出处。&nbsp;</span></strong></p><p><br  /></p><section data-id="1658"><section><section><section data-id="1658"><section><section><section data-id="1658"><section><section><section data-id="1658"><section><section><p><span><strong>相关阅读</strong></span></p></section><p><p><img src="image/20201014/ec237188ae1e9c03eb4d9814f31b18ab_12.gif" /></p></p><p><br  /></p><p><span>科普动画|MRI、CT、PET分别是怎么扫描图像的？</span><br  /></p><p><br  /></p><p><span>CT图像处理技术哪家强？</span><br  /></p><p><br  /></p><p><span>【知识储备】如何在低辐射剂量下得到优质的CT图像质量</span><br  /></p><p><br  /></p><p><span>未来十年CT技术的发展方向</span><br  /></p></section></section></section></section></section></section></section></section></section></section></section><p><br  /></p><p><span><strong><span><p><img src="image/20201014/225eae26a91575de7508aebe3e999278_13.jpg" /></p></span></strong></span></p>