CT窗口技术简介

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                    <section><section powered-by="gulangu"><section><p><img src="image/20201019/efffb5a45b736c6a33c1ebec42cdfa58_1.gif" /></p></section></section><section powered-by="gulangu"><section><section> <p><img src="image/20201019/cb07c0553913a08e331244e3c026e147_2.png" /></p> <section><p>CT窗口技术功能</p></section> </section> <p><img src="image/20201019/8dd37d1f79fcb28473aa4fa1a94a0bfa_3.png" /></p> <section></section></section></section><section powered-by="gulangu"><section><section><p>&nbsp; &nbsp; &nbsp; &nbsp; 窗口技术是CT检查中用以观察人体不同密度组织的一种显示技术，包括窗宽（window width）和窗位（window level）。</p><p>&nbsp; &nbsp; &nbsp; &nbsp;由于各种组织结构或病变具有不同的CT值，因此欲显示某一组织结构细节时，应选择适合观察该组织或病变的窗宽和窗位，以获得最佳显示。</p></section></section></section><section powered-by="gulangu"><section><section> <p><img src="image/20201019/cb07c0553913a08e331244e3c026e147_2.png" /></p> <section><p>CT窗口技术介绍</p></section> </section> <p><img src="image/20201019/8dd37d1f79fcb28473aa4fa1a94a0bfa_3.png" /></p> <section></section></section></section><section powered-by="gulangu"><section><section><p>1、衰减系数是衡量某种物质对x线的衰减程度的一个参数，是干涉散射、光电吸收和康普顿散射的系数之和。</p><p>&nbsp; &nbsp; &nbsp;Absorption（吸收） + Scattering（散射） =&gt; Attenuation（衰减）</p><p>&nbsp; &nbsp; &nbsp; X线的指数衰减规律如下图。</p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/b6369f0a9052a7f055698c73e605bd7e_6.jpg" /></p></section></section><section powered-by="gulangu"><section><section><p>2、CT值的定义;</p><p>&nbsp; &nbsp; &nbsp;&nbsp;因为衰减系数m的定量描述非常麻烦，所以改用相对于水的衰减计算出来的CT值，来衡量x线对物质的衰减程度。CT值的计算公式如下。（水的衰减系数为<span>0.19</span><span>）</span></p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/08c5b60b1c3e911e768f806c35202cf2_7.jpg" /></p></section></section><section powered-by="gulangu"><section><section><p>&nbsp; &nbsp; &nbsp; 各组织的CT值如下图。</p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/e0d7e56085fbcf9217cb3ed5ff25f214_8.jpg" /></p></section></section><section powered-by="gulangu"><section><section><p>3、窗宽与窗位</p><p>&nbsp; &nbsp; &nbsp; &nbsp; 如果使用的CT值按2000个计，那么图像从全黑到全白就要显示2000个不同的黑白程度，即显示2000个灰度等级。</p><p>&nbsp; &nbsp; &nbsp; &nbsp;一般人眼最多能分辨60-80个黑白分级。由于人眼对黑白程度的低分辨能力，将识别不出CT像已表现出来的许多生物信息。为弥补人眼的低灵敏度，故CT采用窗口技术解决这一问题。</p><p>&nbsp; &nbsp; &nbsp; &nbsp;窗宽（WW）表示所显示CT值的范围。</p><p>&nbsp; &nbsp; &nbsp; &nbsp;窗外（WL）表示将某一CT值对应于灰度级中心的位置，这个CT值表示窗位。</p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/3c1804e2f3fea7292f1f6b639d02b3d7_9.jpg" /></p></section></section><section powered-by="gulangu"><section><section> <p><img src="image/20201019/cb07c0553913a08e331244e3c026e147_2.png" /></p> <section><p>窗宽窗位对图像的影响</p></section> </section> <p><img src="image/20201019/8dd37d1f79fcb28473aa4fa1a94a0bfa_3.png" /></p> <section></section></section></section><section powered-by="gulangu"><section><section><p>1、窗宽对图像的影响：窗宽越大，对比度越小；<span>窗宽越小，对比度越大。</span></p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/b44fa01f7d181c1c096913969aef64b0_12.jpg" /></p></section></section><section powered-by="gulangu"><section><section><p>2、窗位的高低影响图像的亮度：窗位低图像亮度高呈白色；窗位高图像亮度低呈黑色。</p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/3e981a68a8f26fb3d24c7d289b9fe525_13.jpg" /></p></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>欢</p></section></section></section> </section><section> <section powered-by="gulangu"><section><section><p>迎</p></section></section></section> </section><section> <section powered-by="gulangu"><section><section><p>关</p></section></section></section> </section><section> <section powered-by="gulangu"><section><section><p>注</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> <section powered-by="gulangu"><section><p><img src="image/20201019/7d80e3e02dcb8e2065691eeef1890965_14.jpg" /></p></section></section> </section><section> <section powered-by="gulangu"><section><section> </section></section></section> </section><section> <section powered-by="gulangu"><section><section><p>关注我们</p><p>一起涨姿势！</p></section></section></section> </section></section></section></section>