Chengdu Shuangliu Airport all of a sudden fire, the use of "weak photon human security screening device" was called off. In fact, "weak photon human security checker" from July has been put into the Shuangliu airport use, only to eleven airport traffic peak to attract the attention of the community.
▲Weak Photon Human Security Checker Use Scene
Another netizen broke the news that there is no "Weak Photon Human Security Checker", the so-called "Weak Photon" is in fact the use of X-rays to see through the face, which is hazardous to human health.1
At one time, the "Weak Photon Human Security Checker" swept through the people worried, the community is very concerned about the safety of the human body.
The safety of the security checker on the human body.
"Weak photon human security checker", really harmful to the human body?
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Before analyzing, we first need to clarify a fact? There is no such thing as a "weak photon human security checker", which does utilize X-rays for security checks. So the following question becomes:
Is the X-ray security checker used at Chengdu Shuangliu Airport harmful to the human body.
When it comes to X-rays, no one seems to be afraid of them, and we still need to get clear about what X-rays actually are.
X-rays are a group of electromagnetic waves with a wavelength of 0.01 nanometers to 10 nanometers, first discovered by Wilhelm R?ntgen. It was first discovered by Wilhelm R?ntgen. Its effect on the human body, there are two main:
Penetration
X-rays on a variety of substances have a certain degree of penetration, and the penetration strength and the wavelength of the X-rays, the substance's atomic number or density. It is because of the penetrating nature of X-rays that doctors are able to utilize equipment such as X-ray machines and CTs to examine a patient's body.
▲The first X-ray photograph in human history, of Mrs. Roentgen's hand
Biological effects
Because X-rays have high energy, irradiation of the human body can lead to cellular damage, inhibition of growth, and even destruction of the genetic material to cause cancer.This property of X-rays can be both This characteristic of X-rays can be used to kill certain light-sensitive cancer cells in the human body, but also may have an effect on normal cells, inducing health problems.
So, in terms of intrinsic properties, X-rays are indeed harmful to the human body.
However, as the old saying goes, "Talking about toxicity in isolation from dose is hooliganism". For example, a daily intake of less than 6g of salt is not only harmless to the human body, but also a guarantee of normal cell functioning. However, once the long-term intake of over-measurement, salt will become a high blood pressure of the accomplices.
So X-ray security checker in the end there is no harm, or to see the security checker radiation X-ray dose.
Calculating the amount of X-rays absorbed by the human body is more complicated, the intensity of X-rays, the surface area of the irradiated part and the length of the irradiated part should be taken into account, and the related measurement data have a dozen or so of injections, line energies, energy-transmitting line densities, and absorption metering rates. Today, Tadpole introduces two commonly used concepts:
Dose Equivalent (H)
Indicates the effect of radiation on the human body
Q refers to the Quality Factor of radiation, which is related to the source of the radiation, and D refers to the dose absorbed by the human body. The unit of dose equivalent is sievert (Sv). For every 1 Sv of radiation received by the body, the chance of cancer increases by 0.0165.
Average absorbed dose (DT)
Indicates the amount of energy absorbed per unit of mass of the affected object by the delivery of ionizing radiation
mT refers to the mass of the organ, and Ddm refers to the measure of absorption at a point on the organ, which, by integrating to find the The average value gives the radiation dose absorbed by the organ. The unit is the Gray (Gy).2
The two units are in fact equivalent, and the absorbed dose equivalent of radiation of 1 Sv in 1 sievert produces the same biological effect as a high-energy X-ray of 1 Gy in 1 Gray.
According to the "Basic Standard for Protection against Ionizing Radiation and Safety of Radiation Sources" developed by China, the incident dose of an X-ray machine should not exceed 10mGy in a single use;3 and according to media reports, the radiation dose of the "weak photon body screening device" at the Chengdu Shuangliu International Airport at one time is controlled to be within 0.2?Sv ( 1Sv = 1000mSv= 1000000?Sv).1
So if you've been through the screening process once during the 11th hour, you don't need to worry about the amount of radiation you're exposed to - it's not much more than smoking a cigarette.
However, due to the cumulative effect of X-rays, the screening device needs to be utilized with great caution. If everywhere can encounter a small dose of X-rays, there is a risk of accumulating too much without realizing it. Therefore, the State Ministry of Environmental Protection has sent a letter to the Sichuan Provincial Environmental Protection Department, requiring it to unauthorized illegal production, sales, use of X-ray body screening equipment units, and ordered to immediately stop the illegal behavior, to ensure public safety.
Truth: Although X-rays have the ability to cause harm to the body, if the radiation dose is very small, an occasional security check will not have a substantial impact on human health.
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References
1 Li, Ming. (2016 October1). Chengdu Airport Body Screening Machine Allegedly Contains X-rays, New Beijing News. Retrieved October 13,2016,fromepaper.bjnews.com
2 Zheng Junzheng, Zeng Zhi. A review of the systematic evolution of ionizing radiation quantities and units[J]. Atomic Energy Science and Technology, 2009, 43(B12): 177-183.
32002 G B. Basic Standard for Protection against Ionizing Radiation and Safety of Radiation Sources [S][D]. , 2002.
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Author: Zhao Yanchang