X-ray fluoroscopy: X-rays pass through the body and form an image on a fluorescent screen; X-ray film: X-rays pass through the body and form an image on the film. Many parents believe that it is not advisable to take X-ray films for children with cough or fever because of the high radiation level, and that it is safer to take fluoroscopy. In fact, the amount of radiation from fluoroscopy is much greater than that from a film. Domestic experts have measured that the dose of X-rays received by adults during a chest X-ray examination is 20 to 30 times that of an ordinary film. In children, due to crying and other uncooperative factors, doctors tend to extend the fluoroscopy time in order to observe the lesion carefully, and the X-ray dose received is much larger than the theoretical one. Therefore, fluoroscopy should be the preferred method of chest examination, and fluoroscopy is a useful supplement to fluoroscopy, which means that when the fluoroscopy is suspicious and it is difficult to make a definite diagnosis, the lesion can be seen more clearly by rotating the body position through fluoroscopy. On the other hand, the clarity of fluoroscopic images is much worse than that of radiographs, and small lesions and fine structures are easily missed. In addition, fluoroscopy cannot record the images of lesions, which is not conducive to the review and comparison of lesions. In developed countries such as the United States and Japan, fluoroscopy has been largely eliminated. The few countries that still use this method are also trying their best to reduce its usage. Not long ago, many domestic radiation protection experts also unanimously called: if children receive too much X-ray radiation, may lay the root of cancer, should be as soon as possible to “stop” children X-ray chest X-ray examination. At present, some large hospitals in China have also abolished fluoroscopy. Therefore, it is recommended that you should try to choose X-ray instead of fluoroscopy if you are allowed to do so. The damage to the human body from a small number of X-rays is minimal. Of course, many people may still worry that even if the X-rays are taken, the dose of X-rays released will be very damaging to the human body. However, the damage caused by a small number of X-rays is negligible. Scientific studies have shown that the dose of X-rays that can cause damage to the human body is 500-1000 mGy (mGy is the absorbed dose unit of X-rays). According to the existing regulations, the radiation dose of the regular hospital daily chest X-ray for patients is only about 0.4 mGy, especially now many hospitals have adopted digital X-ray photography technology (that is, people often called DR, CR), which not only imaging speed, image clarity, and small radiation, than ordinary X-ray machine patient X-ray dose reduced by more than 50%, so people can not worry too much .