Why can x-rays penetrate the human body?

It is found that for substances made of lighter atoms, such as muscles, X-rays rarely weaken when penetrating, but for substances made of heavier atoms, such as bones, X-rays are almost completely absorbed. So when you look at the human body with X-rays, you leave the shadow of the tissues in the human body on the screen, and you can see the lungs through the muscles of the human body.

X-ray is an electromagnetic wave with extremely short wavelength and great energy. The wavelength of X-ray is shorter than that of visible light (about 0.00 1 ~ 10 nm, and the wavelength of X-ray used in medicine is about 0.00 1 ~ 0. 1 nm), and its photon energy is tens of thousands to hundreds of thousands of times greater than that of visible light. It was discovered by German physicist W.K. Roentgen in 1895, so it is also called Roentgen ray.

X-rays have strong penetrating ability, and can penetrate many substances that are opaque to visible light, such as ink paper, wood and so on. This invisible ray can make many solid substances have visible fluorescence, make photographic negatives sensitive and ionize air. X-rays were originally used for medical imaging diagnosis and? X ray crystallography. X-ray is also a kind of radiation harmful to human body, such as ionizing radiation.

20 17,101The list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization on October 27th was preliminarily sorted out for reference. X-ray and gamma-ray radiation are included in the list of carcinogens. 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.