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  3. If you’ve traveled by airplane in the past few years, chances are you’ve walked through a full body scanner at the security chec

If you’ve traveled by airplane in the past few years, chances are you’ve walked through a full body scanner at the security chec

admin2022-02-03  52
问题     If you’ve traveled by airplane in the past few years, chances are you’ve walked through a full body scanner at the security checkpoint.
    The first generation of full body X-ray scanners rolled out in airports across the US in 2008. Known as backsatter scanners, there was a bit of an uproar from consumers when these came on the scene. Fliers feared the imaging would visually strip them of their clothes in front of the Transportation Security Administration (TSA) agents. Some health experts also worried that these models might expose people to unnecessary radiation.
    But in 2013, the TSA replaced backscatter scanners with new-and-improved scanners, called millimeter wave screeners. They fixed the "see you naked"issue. These devices create a standard outline of a person, rather than a detailed image of the person’s body. They’re also an improvement for your health. The millimeter wave scanners use low power radio frequency waves to create the image. The frequency is the same as that used for Wi-Fi devices. If you stood for three seconds in a scanner, it would be no more radiation exposure than standing in front of your computer router at home.
    Backscatter scanners, meanwhile, can still be found in other places like jails and courthouses. They do expose people to small amounts of X-rays, but the Food and Drug Administration (FDA) considers them safe. A person receives more radiation from naturally occurring sources in less than an hour of ordinary living than from one screening with any general-use X-ray security system, says the FDA. Yet others are not so convinced.
    The European Union prohibits the backscatters. Some scientists believe that even very low level X-ray exposure could increase the risk of cancer. " I would agree that the individual risk associated with X-ray scanners is likely to be extremely small," says David Brenner, head of Columbia University’s Center for Radiological Research. "The issue of concern is when the X-ray scanners are used in a very high volume setting (just under a billion security screens occur each year in US airports). A very tiny risk multiplied by a billion has the potential to represent a public health issue. "
What is the passage mainly about?
选项 A、The improvement of airport security.
B、The significance of full body imaging.
C、Uses of the millimeter wave screener.
D、Health concerns about X-ray scanning.
答案D
解析 主旨题。文章全篇都在讲述X射线扫描仪以及其所带来的健康问题，由此可知，文章的主题是X射线扫描所带来的健康问题。故选D。
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