为什么多层螺旋CT能风靡世界20年？

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                    <section><section powered-by="gulangu"><section><section><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>医疗器械第一新媒体</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><p>1998年诞生的多层螺旋CT是CT技术进入新阶段的标志，也是各家厂商研究关注的热点，更是当前CT发展的主要代表产品。为何多层螺旋CT能风靡世界20年，经久不衰？今天小编就带你来一探究竟。</p><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section><section></section><section></section><section></section></section><section><p><strong>什么是螺旋CT?</strong></p></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><p>首先我们来看一下常规CT的扫描方式。为了避免高压电缆和数据电缆在旋转过程中发生缠绕问题，旋转控制必须采用<strong>启动-加速-均速-取样-减速-停止</strong>等几个过程。</p><p><p><img src="image/20201014/6c6cd4089bc6db388b51946c11338734_2.png" /></p></p><p><br  /></p><p><span>这就大大限制了扫描速度。特别是在造影剂使用的情况下，有效的时间内只能扫描有限的层面数。</span>层厚定位选择所引起的部分容积效应导致漏诊。而且也不能准确地重建三维图像和多方位图像。</p><p><span><br  /></span><br  /></p><p><p><img src="image/20201014/3877eacbdb6fe28bce2e6bfba6de7cf2_3.jpg" /></p></p><p><br  /></p><p><span>螺旋CT与常规CT最大的不同就在于：螺旋CT是像切长条吐司面包一般，</span><strong>一层一层连续扫描。（scan slice by slice）</strong><br  /></p><p><br  /></p><p><p><img src="image/20201014/2a0f8a62ea11054de45918b70939543c_4.jpg" /></p></p><p><br  /></p><p>在扫描过程中，X线管连续地围绕受检者旋转，与此同时承托着受检者的病床匀速的向机架的扫描孔内推进(或匀速地离开扫描孔)，这样X射线束在受检者身上勾画出<strong><span>一条螺旋线轨迹</span></strong>，因此称之为<strong>螺旋CT （Spiral CT或Helical CT ）。</strong></p><p><strong><br  /></strong></p><p>螺旋线限定了人体组织的一段容积，所以这一技术也叫作<strong>容积扫描（ Volume Scan ） </strong>。</p><p><br  /></p><p>说到螺旋CT，就不得不提<strong>滑环技术（slip-ring transmission technic）</strong>。</p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><strong>滑环技术</strong></p><p>滑环由一个导电环和一个碳刷构成。碳刷不动，导电环可以旋转，这样可以达到静止部件和旋转运动部件之间相互电信号的传递。</p></section></section></section></section></section></section><section powered-by="gulangu"><section><section><svg xmlns="http://www.w3.org/2000/svg" x="0px" y="0px" viewbox="0 0 630.7 35" width="630.7"><g><g><path d="M10.9,19.9c6,0,10.9,6.7,10.9,15H0C0,26.7,4.9,19.9,10.9,19.9z" fill="#ffffff"></path><path d="M32.6,19.9c6,0,10.9,6.7,10.9,15H21.7C21.7,26.7,26.6,19.9,32.6,19.9z" fill="#ffffff"></path><path d="M54.4,19.9c6,0,10.9,6.7,10.9,15H43.5C43.5,26.7,48.4,19.9,54.4,19.9z" fill="#ffffff"></path><path d="M76.1,19.9c6,0,10.9,6.7,10.9,15H65.2C65.2,26.7,70.1,19.9,76.1,19.9z" fill="#ffffff"></path><path 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d="M511.1,19.9c6,0,10.9,6.7,10.9,15h-21.7C500.2,26.7,505.1,19.9,511.1,19.9z" fill="#ffffff"></path></g><g><path d="M532.9,20c6,0,10.9,6.7,10.9,15H522C522,26.7,526.9,20,532.9,20z" fill="#ffffff"></path><path d="M554.6,20c6,0,10.9,6.7,10.9,15h-21.7C543.7,26.7,548.6,20,554.6,20z" fill="#ffffff"></path><path d="M576.4,20c6,0,10.9,6.7,10.9,15h-21.7C565.5,26.7,570.4,20,576.4,20z" fill="#ffffff"></path><path d="M598.1,20c6,0,10.9,6.7,10.9,15h-21.7C587.2,26.7,592.1,20,598.1,20z" fill="#ffffff"></path><path d="M619.8,20c6,0,10.9,6.7,10.9,15H609C609,26.7,613.8,20,619.8,20z" fill="#ffffff"></path></g></g></svg></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201014/627031846e059e93944a0b7009b63a98_5.png" /></p></section></section></section><section powered-by="gulangu"><section><section><p>滑环分布在<span>圆柱表面上</span></p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201014/6ebe296fec431eaee727ae70ae95e122_6.png" /></p></section></section></section><section powered-by="gulangu"><section><section><p><span>滑环分布在<span>圆柱切面上</span></span></p><p><span><span><br  /></span></span></p><p>滑环技术的应用，使<strong>连续扫描</strong>成为可能，从而<strong>实现了X射线的连续曝光，数据的连续采集，检查床的连续移动，将单层扫描变成容积扫描</strong>，缩短了扫描时间，大大扩展了CT的应用范围和各种功能。</p><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section><section></section><section></section><section></section></section><section><p><strong>螺旋CT的优点</strong></p></section></section></section></section><section powered-by="gulangu"><section><section><p>1、螺旋CT的<strong><span>连续扫描</span></strong>，使扫描范围在<span><strong><span>24～30s内达到24～30cm</span></strong></span>，可满足绝大部分不同部位的CT检查。多数患者可在一次屏气中完成扫描，避免了漏扫和重扫<span>。&nbsp;</span></p><p><span><br  /></span></p><p><span>2.由于避免了呼吸运动引起的扫描遗漏以及它具有在选定位置及间隔上进行</span><span><strong>回顾性重建的能力</strong></span><span>，所以提高了病灶检出率。</span></p><p><span><br  /></span></p><p><span>3.螺旋CT的连续扫描使扫描时间缩短，不但有益于危重患者的检查，而且在增强扫描时可使几乎全部扫描都在增强高峰期完成，不但能获得最佳增强效果，还可</span><span><strong>减少造影剂用量。</strong></span></p><p><span><br  /></span></p><p><span>4.螺旋CT提高了病灶密度测量的准确性，由于</span><span><strong>可在 z 轴任何部位进行图像重建</strong></span><span>，因而保证了任何病灶均可以在其中心进行图像重建，减少了部分容积效应的影响。&nbsp;</span></p><p><span><br  /></span></p><p><span>5.任何部分均可进行</span><span><strong>多断面或三维图像重建</strong></span><span>，而且由于螺旋CT扫描时避免了病变部位的移动，因而</span><span>重建图像质量好。</span></p><p><span><br  /></span></p><p><span>&nbsp;6.</span><span><strong>扫描时间短</strong></span><span>，使病人更容易接受或耐受CT检查，这对危重病人及只能短时间保持功能极限位的快速诊断更有意义。</span></p></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section><section></section><section></section><section></section></section><section><p><strong>螺旋CT的临床应用&nbsp;</strong></p></section></section></section></section><section powered-by="gulangu"><section><section><p><strong>心脏</strong></p><p><strong><br  /></strong></p><p><p><img src="image/20201014/1aa1ce0712f3b9b00a914aa768ebccde_7.gif" /></p></p><p><strong><span></span></strong><br  /></p><p><span>64排螺旋CT是诊断冠心病的新手段，与冠状动脉造影相比毫不逊色。其最大的优点是无创伤，病人只需静脉内注射60～80毫升显影剂，就可以清晰显示冠状动脉的立体影像。其特点是阴性预测价值高，即64排螺旋CT正常者，冠状动脉造影也会正常。</span></p><p><strong><br  /></strong></p><p><strong>肺</strong></p><p><br  /></p><p><span></span></p><p>低剂量螺旋CT对肺部的筛查有助于发现早期肺癌，特别是肺部小结节，其诊出率远高于常规胸片，是早期肺癌诊断的“<span><strong>金标准</strong></span>”。<span>低剂量螺旋CT扫描获得图像质量和常规剂量扫描差异不大,且患者所接受辐射剂量大幅度降低。</span></p><p><span><br  /></span></p><p><strong>骨骼系统的三维重建</strong><br  /></p><p><strong><span><br  /></span></strong></p><p>64排螺旋CT能用于骨科手术的术前检查，外伤患者的骨折检查。螺旋CT可以<span>进行容积扫描，可以应用MPR进行多角度的重组图像进行观察，也可以进行三维重建，对骨骼进行整体显示。</span></p><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><p>编者按：俗话说“没有金刚钻，不揽瓷器活。”螺旋CT运用了滑环技术，使得扫描床在匀速移动的过程中，球管-探测器进行连续单方向旋转来采集数据。大大地缩短了原始数据获取的时间。解决了扫描运动的脏器的难题。这或许是螺旋CT能风靡世界20年的原因之一吧。你认为呢？</p><p><br  /></p></section></section></section></section><p><strong><span>本文由整理撰写，转载请注明出处。</span></strong></p><p><br  /></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_8.gif" /></p></p><p><span></span></p><p><span>同档次CT，国产与进口的价格竟相差2倍？</span><br  /></p><p><br  /></p><p><span>重磅！东软医疗发布国产首台超高端256层CT——NeuViz 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