CT系统的性能参数简介

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                    <section><section powered-by="gulangu"><section><p><img src="image/20201019/cb5c859e4c702a480eea95f58a8b3a86_1.gif" /></p></section></section><section powered-by="gulangu"><section><section><p>空间分辨力</p></section> <section></section> <section></section> <section></section></section></section><section powered-by="gulangu"><section><section><p>&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;空间分辨力，在CT设备中又称为几何分辨力或高对比度分辨力，是指鉴别细微结构的能力，也就是显示最小病灶或结构的能力。</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;空间分辨力就用最小的针距分辨能力进行描述，用每厘米可分辨的线对数（lp/cm）来表示。</p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/5eee970a3230137e5cc810563aeb13f5_2.jpg" /></p></section></section><section powered-by="gulangu"><section><section><p>纵向分辨力</p></section> <section></section> <section></section> <section></section></section></section><section powered-by="gulangu"><section><section><p>&nbsp; &nbsp; &nbsp; &nbsp; 纵向分辨力也称Z轴分辨力，有效层厚（成像厚度）就是Z轴上的分辨力。</p><p>注：空间分辨力是指XY平面的分辨力。</p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/1e9b161b8ebefd3ed8d0a27ba01a5102_3.jpg" /></p></section></section><section powered-by="gulangu"><section><section><p>密度分辨力</p></section> <section></section> <section></section> <section></section></section></section><section powered-by="gulangu"><section><section><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;密度分辨力，又称低对比度分辨力，它表示系统所能分辨的对比度差别的能力。</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;密度分辨力，通常用百分数来表示，例如一个CT系统的密度分辨力为0.3%，就意味着如果两部分组织的密度差别大于0.3%都可以区分开来，当密度差别小于0.3%，就无法区分。</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;测量密度分辨力方法采用一个带有许多孔的圆柱形模型，模型中的孔注入不同密度的物质，来改变孔与背景的对比度。肉眼判断能观察的最小孔的直径大小。</p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/ed0851f279944c84b3ddc2284fb138b6_4.jpg" /></p></section></section><section powered-by="gulangu"><section><section><p>注：空间分辨力和密度分辨力是两个相互制约的参数，空间分辨力的提高会降低低密度分辨力，这是因为其他条件不变时，像素越小，每个像素所含的信息量就越小，于是降低了密度分辨力。</p></section></section></section><section powered-by="gulangu"><section><section><p>噪声</p></section> <section></section> <section></section> <section></section></section></section><section powered-by="gulangu"><section><section><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;噪声是指在均匀物体的影像中，CT值在平均值上下的随机涨落，它可以用CT值的标准偏差来表示。</p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/fba5afebc34f655befc5188e4e0e05a5_5.jpg" /></p></section></section><section powered-by="gulangu"><section><section><p>&nbsp; &nbsp; &nbsp; &nbsp; CT中的噪声是指均匀物质的CT图像（比如水）中CT值的上下波动，可以用标准偏差来表示，它描述了在均值附近的CT值的分布。</p></section></section></section><section powered-by="gulangu"><section><p><img src="image/20201019/8d28e099341699b550f3aecb8d87dae0_6.jpg" /></p></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/20201019/3f40be0ec26fa5ac748f71d3b12018fd_7.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>