DR三种平板探测器的工作原理及优缺点

admin · 发表于 2020-10-21 13:55:10

<img src="http://mmbiz.qpic.cn/mmbiz/A1DicCH9Vl6N81EEZNTTD5LibxzSnnmKnS7qnsibFHWszxFtVDKM3ib4ECH0fsZRcic2r2ibricN3DmgBL7XuM5D4M2rw/0" style="white-space: normal;" data-ratio="0.20725388601036268" data-w="386" /><span style="max-width: 100%; color: rgb(62, 62, 62); white-space: pre-wrap; background-color: rgb(255, 255, 255); font-size: 19px; font-family: 仿宋; word-wrap: break-word !important; box-sizing: border-box !important;">“<span style="max-width: 100%; white-space: pre-wrap; background-color: rgb(255, 255, 255); color: rgb(79, 129, 189); font-weight: bold; font-size: 19px; font-family: 仿宋; word-wrap: break-word !important; box-sizing: border-box !important;"><span style="max-width: 100%; color: rgb(62, 62, 62); white-space: pre-wrap; background-color: rgb(255, 255, 255); font-size: 19px; font-family: 仿宋; word-wrap: break-word !important; box-sizing: border-box !important;">”关注我们，每日分享维修知识、医疗器械资讯信息！<img data-s="300,640" src="http://mmbiz.qpic.cn/mmbiz/A1DicCH9Vl6N81EEZNTTD5LibxzSnnmKnSQ3EDQGS52d4om3dO3lxNSSicribOdXmfeHQZCMvSpuDuibHkh6ib09RqBA/0" data-ratio="0.875886524822695" data-w="282" />(一)碘化铯/非晶硅型：概括原理：X线先经荧光介质材料转换成可见光，再由光敏元件将可见光信号转换成电信号，最后将模拟电信号经A/D转换成数字信号。具体原理：1、曝光前，先使硅表面存储阳离子而产生均一电荷，导致在硅表面产生电子场;2、曝光期间，在硅内产生电子-空穴对，且自由电子游离到表面，导致在硅表面产生潜在的电荷影像，在每一点上电荷密度与局部X线强度相当。3、曝光后，X线图像被储存在每一个像素中;4、半导体转换器读出每一个素，完成模数转换。优点：1、转换效率高;2、动态范围广;3、空间分辨率高;4、在低分辨率区X线吸收率高(原因是其原子序数高于非晶硒);5、环境适应性强。缺点：1、高剂量时DQE不如非晶硒型;2、因有荧光转换层故存在轻微散射效应;3、锐利度相对略低于非晶硒型。佳能DR已独家采用目前世界上最先进的荧光介质氧化钆，有效弥补和改善了上述缺点。(二)非晶硒型概括原理：光导半导体直接将接收的X线光子转换成电荷，再由薄膜晶体管阵列将电信号读出并数字化。具体原理：1、X 线入射光子在非晶硒层激发出电子-空穴对;2、电子和空穴在外加电场的作用下做反向运动，产生电流，电流的大小与入射的X线光子数量成正比;3、这些电流信号被存储在TFT的极间电容上，每一个TFT和电容就形成一个像素单元。优点：1、转换效率高;2、动态范围广;3、空间分辨率高;4、锐利度好;缺点：1、对X线吸收率低，在低剂量条件下图像质量不能很好的保证，而加大X线剂量，不但加大病源射线吸收，且对X光系统要求过高。2、硒层对温度敏感，使用条件受限，环境适应性差。(三)CCD型概括原理：由增感屏作为X线的交互介质，加CCD来数字化X 线图像。具体原理：以MOS电容器型为例：是在P型Si的表面生成一层SiO2，再在上面蒸镀一层多晶硅作为电极，给电极P型Si 衬底加一电压，在电极下面就形成了一个低势能区，即势阱。势阱的深浅与电压有关。电压越高势阱越深。而光生成电子就储于势阱之中。光生电子多少与光强成正比。所以所存储的电荷量也就反应了该点的亮度。上百万的光敏单元所存储的电荷就形成与图像对应的电荷图像。优点：1、空间分辨率高;2、几何失真小;3、均匀一致性好。缺点：1、转换效率低(原因是CCD系统采用增感屏为其X线交互介质，它的MTF调制传递函数和DQE量子检测效能都不会超过增感屏。另外，由于增感屏被X线激发的荧光通常只有小于1%能够通过镜头进入CCD)。2、生产工艺难：CCD面积难以做大，需多片才能获得足够的尺寸，这便带来了拼接的问题，导致系统复杂度升高可靠性降低，且接缝两面有影像偏差。3、像素大小由CCD的最小体积决定，而CCD体积制造工艺受限。以上CCD技术的这些固有缺陷，使其已经不能代表DR系统的主流发展方向，逐步淘汰中。<img data-s="300,640" src="http://mmbiz.qpic.cn/mmbiz/A1DicCH9Vl6N81EEZNTTD5LibxzSnnmKnS13QroM6ibPUaDiaaGTAEwUlicyZB4f60bJJHgtf70yxaebOMGjxTVVBrQ/0" style="white-space: normal;" data-ratio="0.9920948616600791" data-w="" />您看此文耗时<img src="http://b255.photo.store.qq.com/psb?/V13AWLGJ32XyzL/w8pY6Xeekr4WiASiPqFeI4*nEQTimG2CRlYpMNObWp0!/b/dAoWBJiBCwAA&bo=EAAkAAAAAAACABA!&rf=photoDetail" height="48" width="16px" data-ratio="2.25" data-w="16" width="16px" src="http://b255.photo.store.qq.com/psb?/V13AWLGJ32XyzL/w8pY6Xeekr4WiASiPqFeI4*nEQTimG2CRlYpMNObWp0!/b/dAoWBJiBCwAA&bo=EAAkAAAAAAACABA!&rf=photoDetail" style="border: 0px; background-attachment: scroll; background-image: none; word-wrap: break-word !important; box-sizing: border-box !important; width: 16px !important; visibility: visible !important; background-position: 0% 0%;" /> <img src="http://b255.photo.store.qq.com/psb?/V13AWLGJ32XyzL/sdgIQmdgpbv1qhfBaqQI7igWbfePRJtEopMnzVOJBGo!/b/dGOYCJj9CgAA&bo=EAAkAAAAAAACABA!&rf=photoDetail" height="48" width="16px" data-ratio="2.25" data-w="16" width="16px" src="http://b255.photo.store.qq.com/psb?/V13AWLGJ32XyzL/sdgIQmdgpbv1qhfBaqQI7igWbfePRJtEopMnzVOJBGo!/b/dGOYCJj9CgAA&bo=EAAkAAAAAAACABA!&rf=photoDetail" style="border: 0px; background-attachment: scroll; background-image: none; word-wrap: break-word !important; box-sizing: border-box !important; width: 16px !important; visibility: visible !important; background-position: 0% 0%;" />·<img src="http://b255.photo.store.qq.com/psb?/V13AWLGJ32XyzL/07UYdIzYPtLQgP1nOAPqVdialbSQvtB7tfo0sUoS.Es!/b/dAWH*5cMDAAA&bo=EAAkAAAAAAACABA!&rf=photoDetail" height="48" width="16px" data-ratio="2.25" data-w="16" width="16px" src="http://b255.photo.store.qq.com/psb?/V13AWLGJ32XyzL/07UYdIzYPtLQgP1nOAPqVdialbSQvtB7tfo0sUoS.Es!/b/dAWH*5cMDAAA&bo=EAAkAAAAAAACABA!&rf=photoDetail" style="border: 0px; background-attachment: scroll; background-image: none; word-wrap: break-word !important; box-sizing: border-box !important; width: 16px !important; visibility: visible !important; background-position: 0% 0%;" /> <img src="http://b255.photo.store.qq.com/psb?/V13AWLGJ32XyzL/aVOw.rnxsJ1hibzYki6iDKOwNRZySS.nbRjM9y2dfbM!/b/dAY2B5iICwAA&bo=EAAkAAAAAAACABA!&rf=photoDetail" height="48" width="16px" data-ratio="2.25" data-w="16" width="16px" src="http://b255.photo.store.qq.com/psb?/V13AWLGJ32XyzL/aVOw.rnxsJ1hibzYki6iDKOwNRZySS.nbRjM9y2dfbM!/b/dAY2B5iICwAA&bo=EAAkAAAAAAACABA!&rf=photoDetail" style="border: 0px; background-attachment: scroll; background-image: none; word-wrap: break-word !important; box-sizing: border-box !important; width: 16px !important; visibility: visible !important; background-position: 0% 0%;" />只需1秒转发<strong style="max-width: 100%; word-wrap: break-word !important; box-sizing: border-box !important; font-size: 12pt; letter-spacing: 0pt; line-height: 32px; text-align: center; text-indent: 0pt; color: rgb(255, 255, 0); vertical-align: baseline; background-color: rgb(0, 0, 0);">转载<strong style="max-width: 100%; word-wrap: break-word !important; box-sizing: border-box !important; font-size: 12pt; letter-spacing: 0pt; line-height: 32px; text-align: center; text-indent: 0pt; color: rgb(255, 255, 255); vertical-align: baseline; background-color: rgb(0, 0, 0);">是一种<strong style="max-width: 100%; word-wrap: break-word !important; box-sizing: border-box !important; font-size: 12pt; letter-spacing: 0pt; line-height: 32px; text-align: center; text-indent: 0pt; color: rgb(255, 0, 0); vertical-align: baseline; background-color: rgb(0, 0, 0);">智慧<strong style="max-width: 100%; word-wrap: break-word !important; box-sizing: border-box !important; font-size: 12pt; letter-spacing: 0pt; line-height: 32px; text-align: center; text-indent: 0pt; color: rgb(255, 255, 255); vertical-align: baseline; background-color: rgb(0, 0, 0);">，<strong style="max-width: 100%; word-wrap: break-word !important; box-sizing: border-box !important; font-size: 12pt; letter-spacing: 0pt; line-height: 32px; text-align: center; text-indent: 0pt; color: rgb(0, 176, 240); vertical-align: baseline; background-color: rgb(0, 0, 0);">分享<strong style="max-width: 100%; word-wrap: break-word !important; box-sizing: border-box !important; font-size: 12pt; letter-spacing: 0pt; line-height: 32px; text-align: center; text-indent: 0pt; color: rgb(255, 255, 255); vertical-align: baseline; background-color: rgb(0, 0, 0);">是一种<strong style="max-width: 100%; word-wrap: break-word !important; box-sizing: border-box !important; font-size: 12pt; letter-spacing: 0pt; line-height: 32px; text-align: center; text-indent: 0pt; color: rgb(255, 192, 0); vertical-align: baseline; background-color: rgb(0, 0, 0);">美德<strong style="max-width: 100%; word-wrap: break-word !important; box-sizing: border-box !important; font-size: 12pt; letter-spacing: 0pt; line-height: 32px; text-align: center; text-indent: 0pt; color: rgb(255, 255, 255); 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