北华大学电子信息工程专业英语期末翻译(The Application of DSP in medicine)_电子信息工程外文翻译

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The problem of overlapping structures was solved in 1971 with the introduction of the first computed tomography scanner(formerly called computed axial tomography,or CAT scanner).Computed tomography(CT)is a claic example of Digital Signal Proceing.X-rays from many direction are paed through the section of the patient's body being examined.Instead of simply forming images with the detected X-ray, the signals are converted into digital data and stored in a computer.The information is then used to calculate images that appear to be slices through the body.These images show much greater detail than conventional techniques, allowing significantly better diagnosis and treatment.The impact of CT was nearly as large as the original introduction of X-ray imaging itself.Within only a few years, every major hospital in the world had acce to a CT scanner.In 1979, two of CT's principle contributors, Godfrey N.Hounsfield and Allan M.Cormack, shared the Nobel Prize in Medicine.That's good DSP!

The last three X-ray problems have been solved by using penetrating energy other than X-rays, such as radio and sound waves.DSP plays a key role in all these techniques.For example, Magnetic Resonance Imaging(MRI)uses magnetic fields in conjunction with radio waves to probe the interior of the human body.Properly adjusting the strength and frequency of the fields cause the atomic nuclei in a localized region of the body to resonate between quantum energy states.This resonance results in the emiion of a secondary radio 10 The Scientist and Engineer's Guide to Digital Signal Proceing wave, detected with an antenna placed near the body.The strength and other characteristics of this detected signal provide information about the localized region in resonance.Adjustment of the magnetic field allows the resonance region to be scanned throughout the body, mapping the internal structure.This information is usually presented as images, just as in computed tomography.Besides providing excellent discrimination between different types of soft tiue, MRI can provide information about physiology, such as blood flow through arteries.MRI relies totally on Digital Signal Proceing techniques, and could not be implemented without them.Space

Sometimes, you just have to make the most out of a bad picture.This is frequently the case with images taken from unmanned satellites and space exploration vehicles.No one is going to send a repairman to Mars just to tweak the knobs on a camera!DSP can improve the quality of images taken under extremely unfavorable conditions in several ways: brightne and contrast adjustment, edge detection, noise reduction, focus adjustment, motion blur reduction, etc.Images that have spatial distortion, such as encountered when a flat image is taken of a spherical planet, can also be warped into a correct representation.Many individual images can also be combined into a single database, allowing the information to be displayed in unique ways.Forexample, a video sequence simulating an aerial flight over the surface of a distant planet.信息26

Commercial Imaging Products

The large information content in images is a problem for systems sold in maquantity to the general public.Commercial systems must be cheap, and this doesn't mesh well with large memories and high data transfer rates.One answer to this dilemma is image compreion.Just as with voice signals, images contain a tremendous amount of redundant information, and can be run through algorithms that reduce the number of bits needed to represent them.Television and other moving pictures are especially suitable for compreion, since most of the image remain the same from frame-to-frame.Commercial imaging products that take advantage of this technology include: video telephones, computer programs that display moving pictures, and digital television.译文：

1971年，随着第一台计算机断层扫描仪的发明，重叠结构的问题解决了。（计算机断层扫描仪之前叫做计算机X射线轴向分层造影扫描仪，也就是CAT 扫描仪）。计算机断层扫描仪是数字信号处理比较典型的例子。我们用各个方向的X射线扫描病人身体来查出病理。信号转变为数字化数据并存储在电脑中，而不是用检测到的信号简单成像.之后用这些信息计算出似乎是通过身体切片的图像。这些图像比传统的技术显示的图像更加清晰，这就使诊断和治疗更有效。CT的影响几乎和X射线成像本身的发明的影响是一样重要。在短短几年里，世界上所有大医院都引进了CT扫描仪。1971年科马克和亨斯菲尔德因发明CT扫描仪获得诺贝尔医学奖。DSP真好。

通过使用穿透能量比如无线电波和声波解决了最后三个X射线问题，而不是用X射线。DSP在所有这些技术里发挥着至关重要的作用。比如说，核磁共振成像（MRI）使用磁场结合无线电波探测人体的内部。适当地调整磁场的频率和强度就会引起身体特定部位原子的共振，共振在原子能量级之间进行。这种共振会发射出另一种无线电信号，科学家和工程师用DSP技术来处理放在人体周围天线检测到的这种信号。这种检测到的信号的波长和其他特性决定了共振的区域。电磁场的变化使得通过身体的共振区域能够被扫描并成像。就像在CT中那样，这种信息以图像的形式呈现出来。MRI不仅能精确的区分不同的软组织，还能提供生理机能的信息，比如血液在动脉的流动。MRI完全依赖于DSP技术，没有DSP，就没有MRI。

太空

有时，你必须把一张损坏的图片还原。从无人操纵的卫星和太空探测器中提取图像是很频繁的事情。我们总不可能把修理工人带上火星去控制照相机的把手吧！DSP能用很多方法提高在极其不利的条件下拍的图像的质量，例如：调整亮度和对比度，检测锐度，降低噪声，调整焦距，减少移动的污迹等等。空间变形的图像可能扭曲成一个正确的表示，例如遇见拍摄球形行星的平面图。许多独特的图像也可以结合为一个单独的数据库，并以一种独特的方式来展示信息。例如，视频演示在遥远的行星表面模拟飞行。

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商业化图像产品

对于大量卖给一般大众的商业系统来说，大信息量的图像还是一个问题。商业系统必须便宜，这一点和大存储量、传输数据速率高相矛盾。压缩图像解决了这个进退两难的问题。和声音信号一样，图像也包含大量多余的信息，这些图像经过算法处理可以减低其容量。电视和其他能动的图片很适合压缩，因为从框对框来看，大部分图像保持一样。商业化图像产品利用了这个技术，例如视频电话、演示动画的计算机程序、和数字电视。