With the Fukushima nuclear accident that has not ceased for a long time, the public is increasingly concerned about the health effects of radiation. X-ray security checkers, which have become commonplace in airports and subways, have returned to people's sight. What is the radiation of the X-ray security detector? Does it affect our health?
Myths: This type of security machine often appears in train stations, airports, and subway stations. The internal radiation is very strong. Many passengers rush to reach in to get the bag before they get out of time. This is very dangerous and should be kept away as much as possible. Take the black masking bar after you close it, because the shaky masking bar will shake out a small amount of radiation.
Truth: The 2008 Olympic Games, the 2010 World Expo and the Asian Games allowed Beijing, Shanghai, and Guangzhou subways to start a comprehensive pit stop security check. Many people have to take the subway every day to and from work, and they have expressed various anxieties about the security checkers that were originally only used at airports and train stations. In addition to worrying about the direct effects of radiation on the human body, there are also concerns that radiation will affect the food in the bag. Are X-ray security cameras really so scary? Rumor smasher investigators reveal the truth for you.
Luggage X-ray security detectors are the same as medical X-ray diagnostic instruments. They use X-rays to illuminate the detected object to obtain an image of the interior of the object. It is not necessary to achieve medical diagnostic level resolution . According to the national standard GB 15208.1-2005, the single inspection dose of X-ray security inspection equipment should not be greater than 5μGy, and the X-ray dose should be less than 5μGy / h at any place 5cm away from the outer surface of the device (including the entrance and exit of the device) [ 2], this standard is the same as the US FDA standard . In fact, the radiation dose of X-ray security detectors used in subways and airports is much lower than that required by national standards. Taking the X-ray security inspection equipment produced by Shanghai Gaojing Imaging Technology Co., Ltd. used by the Shanghai Metro as an example, according to the data provided by the official website of the company, its single inspection dose is 0.534 μGy, and the radiation dose at the outer surface 5cm is 0.788 μGy / h  is about 1/10 of the upper limit stipulated by national standards. According to the data reported by the United Nations Scientific Committee on Radiation Effects, the radiation dose of a medical X-ray chest X-ray examination is 50 μGy , that is, even if a person is really put into such an X-ray security inspection device used in the Shanghai Metro, it is necessary to It takes about 100 scans to reach the radiation dose received on a chest radiograph--not to mention that such a situation is simply impossible.
Maybe someone will ask, I take the subway every day, the frequency is too many, is the cumulative amount harmful? We do not have clear data on the radiation dose received by ordinary passengers due to security checks each year. However, compared to ordinary passengers, the operators of security inspection equipment will obviously receive more radiation, especially the airport luggage security inspection personnel, often need to manually load or unload the security inspection equipment. In 2003, the U.S. Centers for Disease Control and Prevention conducted a large-scale radiation dose survey on baggage security personnel at six major U.S. airports. The results of the survey report showed that the vast majority (89%) of airport luggage security personnel accepted work because of their work. The radiation dose is less than 12mrem, that is, 120μGy, and the remaining few people are basically less than 60mrem, that is, 600μGy . According to the data reported by the United Nations Scientific Committee on Radiation Effects, the general public, except natural radiation and medical radiation, receives an annual upper limit dose of 1000 μGy . Even airport baggage security personnel, the radiation doses received due to work are much less than This cap. The American Institute of Healthcare Physics also pointed out that because the radiation dose of baggage X-ray security devices is far less than that of medical X-ray machines, and has been fully shielded, even pregnant women can safely engage in the operation of baggage X-ray security devices .
Does the X-ray security device affect the scanned items? Because the radiation of the baggage X-ray security detector is very small, the impact on the scanned item itself can be ignored. But there is a special kind of film, film, which is more sensitive to X-ray radiation. According to a 1994 experiment conducted by the National Association of Photographic Manufacturers (NAPM) on films of different sensitivities from different manufacturers, ISO1600 films have not found any imaging abnormalities after 16 X-ray luggage scans. Minor imaging anomalies were found after two scans . Kodak has given the suggestion that "films above ISO400 should not be subjected to X-ray security inspection" . From the data of the security equipment supplier Gao Jing Company used by the Shanghai Metro, the model with the highest single dose (its single dose is close to the limit set by the national standard) also indicates the ISO1600 film safety . Most of the photographic film we use everyday has a sensitivity below ISO400. Taken together, it is generally considered that ordinary photographic film (excluding X-ray film or other films with strict requirements for imaging) is safe under normal travel conditions through the current security equipment used in airports and subways. However, because the effects of X-rays on films are cumulative, high-sensitivity films should be prevented from passing through X-ray security inspections multiple times. It should be pointed out that X-rays have no effect on digital cameras and can pass security screening with confidence.
In addition, unlike the radioactive element particles leaked from the Fukushima nuclear accident, X-ray scanning will not cause radioactive contamination. After the scan, no radioactive substances will remain on the luggage, and the food scanned by X-rays will not affect the human body. Health is harmful.
Conclusion: Exaggerate the facts. The X-ray security checker used in the airport and subway is not “very powerful” in internal radiation, the dose is much smaller than the X-ray machine used for medical diagnosis, and the radiation around the machine is very weak. Even full-time operators can do without protection. safe job. Although putting your hand into the cover strip to take the bag will indeed increase the amount of radiation received to a certain extent and should be avoided as much as possible, it is not a "very dangerous" thing.