Is ultrasound harmful to human body?

At work, patients often ask, "Doctor, will ultrasound kill cells like X-rays or CT?" Some patients even resist ultrasound examination and constantly urge the examining doctor to finish the examination quickly. In fact, medical ultrasound examination is very safe, the ultrasound dose used in ultrasound examination is very low, the ultrasound output power of normal ultrasound examination equipment is strictly controlled, and the doctor who operates the ultrasound equipment correctly always controls the ultrasound dose. Therefore, normal ultrasound examination has not produced any obvious adverse reactions so far. According to the research, the thermal effect caused by medical ultrasound is safe: first, the sound beam of medical ultrasound works inside the human body, and the heat energy converted from acoustic energy travels in a relatively large volume, so the temperature rise range is relatively large, but the temperature rise is relatively small; Secondly, the sound absorption of body fluids such as blood and amniotic fluid is very small, close to zero, and the temperature rise caused by ultrasound in these body fluids is also very small. For low-intensity ultrasound used in ultrasonic diagnosis, this mechanical motion is very weak and generally does not produce macro-effects. Studies show that the biological effect of ultrasound depends on the dose of ultrasound. In a certain dose, it will not have harmful effects. Because B-ultrasound used for medical diagnosis is of low intensity, less than 100 MW per square centimeter, there is no danger. It is reported that some international organizations have set up various working groups to focus on whether ultrasound examination is harmful to human body, including the World Health Organization and the American Medical Ultrasound Society. Their conclusions are basically the same. It is believed that the wide application of medical ultrasonic diagnostic technology, including the diagnosis of pregnant women, shows obvious medical diagnostic value and effect. Current data show that the benefits of rational use of ultrasound diagnosis far outweigh any possible risks. It can be seen that due to people's universal attention and effective measures, in the decades of using ultrasonic diagnosis, there is no evidence that ultrasonic diagnostic equipment has any harmful effects on patients or doctors. In this sense, ultrasonic diagnosis is safe. (Zhang Shiyuan, Department of Ultrasound, Second Affiliated Hospital of Nanchang University) Editor: Zheng Bo