18.8 X射线
章节大纲
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You probably recognize this somewhat startling image as an image of a human skull. X-rays, which are used to make images like this one, are .
::您可能意识到这幅令人吃惊的图像是人头骨的图像。 X光片是用来制作像这个图像的。Putting X-Rays in Context
::将 X 光放入上下文Electromagnetic waves are vibrating electric and magnetic fields that transfer across space as well as through matter. There are several different types of electromagnetic waves that vary in their frequencies and . Waves with higher frequencies have more energy. The pictured in the Figure represents the full range of frequencies of electromagnetic waves.
::电磁波正在震动电磁场,这些电磁场在空间和物质之间转移。有几种不同类型的电磁波的频率和频率各不相同。高频波的能量较多。图中图示的是电磁波的所有频率。High Energy Waves
::高能电波Electromagnetic waves with the highest frequencies and greatest energy are on the right side of the electromagnetic spectrum in the Figure . X-rays have more energy than any other electromagnetic waves except . For example, X-rays have enough energy to pass through soft tissues such as skin, although not enough to pass through bones and teeth, which are very dense. The bright areas in the skull X-ray shows where X-rays were absorbed by teeth and bones. X-rays are used not only for medical and dental purposes but also to screen luggage at airports (see Figure ).
::图中电磁波频率和能量最高的电磁波位于电磁谱的右侧。X射线比任何其他电磁波的能量都多,但只有以下情况除外:例如,X射线有足够的能量通过皮肤等软组织,尽管不足以通过密度很高的骨头和牙齿。头骨X射线的亮点显示,X射线被牙齿和骨头吸收。X射线不仅用于医疗和牙科目的,而且用于机场的检查行李(见图)。Q: What do the dark areas in an X-ray image represent?
::问题:X光图像中的黑暗区域代表什么?A: The dark areas represent materials that do not absorb X-rays. Instead, the X-rays pass through these areas. For example, in the X-ray image pictured in the Figure , the bag doesn't show up because X-rays pass through the soft cloth, but not the dense objects inside.
::A:黑暗区域代表的是不吸收X光的材料。相反,X光通过这些区域。例如,在图中绘制的X光图像中,包没有出现,因为X光通过软布,而不是里面密度大的物体。Dangers of X-Rays
::X射线的危险Because X-rays are so energetic, they can penetrate many substances, including living cells. Therefore, too much X-ray exposure can be dangerous. It may damage cells and cause cancer. If you’ve had dental X-rays, you may have noticed that a heavy apron was placed over your body to protect it from stray X-rays. Protective aprons like this are made of lead, which X-rays can’t pass through.
::由于X光的强度很高,它们可以穿透许多物质,包括活体细胞。 因此,过多的X光照射可能很危险。 它可能会损害细胞并导致癌症。 如果你有牙科X光,你可能已经注意到在身体上放置了一个沉重的围裙来保护它免受误入的X光。 像这样的保护性围裙是由铅制成的,而X光无法通过。Summary
::摘要-
Electromagnetic waves vary in their frequencies and wavelengths, and waves with higher frequencies have greater energy. The electromagnetic spectrum represents the full range of frequencies of electromagnetic waves.
::电磁波的频率和波长各不相同,高频波的能量更大。 电磁频谱代表电磁波的所有频率。 -
X-rays are high-frequency electromagnetic waves with more energy than any other electromagnetic waves except gamma rays.
::X射线是高频电磁波,其能量超过除伽马射线以外的任何其他电磁波。 -
X-rays are used to make images of bones and teeth inside the body and to see inside luggage at airports.
::X光片用来制作尸体内骨骼和牙齿的图像,并在机场内看到行李。 -
X-rays can penetrate the body, damage cells, and cause cancer.
::X光片可以穿透身体、破坏细胞和致癌。
Review
::回顾-
What are X-rays? Where do they fall in the electromagnetic spectrum?
::什么是X光片? -
How are X-rays used?
::如何使用X光片? -
Why are X-rays dangerous?
::为什么X光片很危险?
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Electromagnetic waves vary in their frequencies and wavelengths, and waves with higher frequencies have greater energy. The electromagnetic spectrum represents the full range of frequencies of electromagnetic waves.
