VOA常速英语2016--全息图或可与CT及超生扫描仪兼容（在线收听）

全息图或可与CT及超生扫描仪兼容

Since the 1980s, doctors have used Magnetic Resonance Imaging machines, or MRI scanners, to look into patients’ bodies without exposing them to the harmful effects of X-rays.An alternating magnetic field created inside the MRI's tube excites hydrogen atoms in the body’s tissues, making them emit radio waves. Those waves can be turned into pictures, similar to X-ray images. The magnet of a new MRI, built by Siemens, has 7 tesla units, making it more than 100,000 (7/0.000065 = 107,692) times more powerful than the earth’s magnetic field. “Using something like 7-tesla imaging, you can do very high resolution imaging, you can get the contrast that you need in order to identify the particular sub-parts of the nuclei that you need, but even high-resolution two-dimensional black-and-white pictures are quite different from three-dimensional color renditions that can be viewed from all angles.Using MRI-generated images of water molecules moving within the brain’s white matter, scientists at the British company Holoxica created a hologram showing the connections between neurons. “The brain is such a complex three-dimensional structure, and sometimes it is quite difficult to describe, or understand, the actual connections.So to see it in 3-D, that may be a short cut to education, and it can reinforce the learning process.”The holographic display is still in prototype phase, but researchers say, once ready for production, it will be compatible not only with MRI machines but also with CT and ultrasound scanners.

自上世纪80年代以来，医生一直使用磁共振成像机器，也就是磁共振扫描仪，来观察患者身体，使患者不必因暴露于X光下而受到伤害。在磁共振扫描仪管道内部产生的交互式磁场会激发人体组织内的氢原子，使氢原子发射出无线电波。这些无线电波的图像近似于X光线的图像。西门子研发的磁共振扫描仪有7特斯拉单元的磁通量，使扫描仪磁场为地球磁场的10万多倍。 “有了7特斯拉的成像技术，就可以做高清成像，就可以得到清晰的对比，从而确定原子核的不同部分。不过，即便是高清的二维黑白图像，也和三维的彩色图像不同，因为后者可以从不同角度观察。

通过使用磁共振扫描仪展示的关于水分子在大脑白质中移动的图像，英国公司Holoxica的科学家发明了一个全息图，可以展示神经元之间的关系。“大脑是极其复杂的三维结构，有时很难描述或理解其中的关系。所以，以三维的方式来观察大脑，对教育来说可能是一个捷径，可以加强学生的学习过程。”虽然全息显示尚处于初期阶段，但专家称，一旦投入生产，不仅与磁共振扫描仪兼容，也能与电脑断层扫描机（CT）和超声扫描仪兼容。