What's the harm of taking X-rays?

X-rays can kill and destroy biological cells to some extent. Overexposure to X-rays will affect physiological functions, cause chromosomal abnormalities and lead to cancer. But proper irradiation will not affect human health. Because the dose used by medical staff for X-ray fluoroscopy and photography is very small, only within the safe dose.

In particular, occasional chest x-ray, gastrointestinal examination, bone X-ray or angiography will not cause adverse reactions. Moreover, the X dose used for filming is not completely absorbed by people, most of it penetrates the human body, and only a small part is absorbed by the human body. If we want to say a specific value, it is that the human body really absorbs only a few tenths or even less of the dose used.

Moreover, the radiation inspection equipment used in major hospitals has long been replaced by digital radiography (CR) and direct digital imaging (DR), and the radiation amount has been greatly reduced, accounting for only the original 1/7.

So to be exact, it is completely correct for normal people to do ct once a week, and it will not affect their health. Medical X-rays will never affect people's health when they are examined and treated.

principle

The simplest way to generate X-rays is to hit a metal target with accelerated electrons. During the impact, the electrons suddenly decelerate, and their lost kinetic energy (1%) will be released in the form of photons, forming a continuous part of the X-ray spectrum, which is called braking radiation. By increasing the accelerating voltage, the energy carried by electrons increases, which may knock out the internal electrons of metal atoms. So the inner layer forms a hole, and the outer layer electrons jump back to the inner layer to fill the hole, and at the same time emit photons with a wavelength of about 0. 1 nm. Because the energy released by the outer electron transition is quantized, the wavelength of the released photons is also concentrated in some parts, forming a characteristic line in the X spectrum, which is called characteristic radiation.

produce

The tough radiation of electrons bombards the metal with high-energy electrons, and the electrons decelerate sharply in the process of hitting the metal. According to electromagnetism, charged particles with acceleration will radiate electromagnetic waves. If the electron energy is large, such as tens of thousands of electron volts, X-rays can be generated. This is the method of generating X-rays used in laboratories, factories, hospitals and other places.

Electron transitions within atoms can also produce x-rays. According to the theory of quantum mechanics, electrons will emit photons when they jump from high energy level to low energy level. If the energy difference between energy levels is large, they can emit photons in the X-ray band.