Why X-ray can be used in medical examination, and what are its characteristics?

X-ray is essentially an electromagnetic wave with a short wavelength of 0.0006-50n m, while the wavelength range of X-ray commonly used in medical X-ray diagnosis is 0.008-0.03 1nm. In addition to the general physical properties, X-rays have the following characteristics related to X-ray imaging:

Permeability:

X-ray has short wave length and strong penetrating power, and it is absorbed or attenuated to some extent during the penetrating process. The higher the voltage of X-ray tube, the shorter the X-ray wavelength and the stronger the penetrating power. On the other hand, the penetrating power of X-rays is also related to the density and thickness of objects. This characteristic is the basis of X-ray imaging.

Fluorescence effect:

X-rays can excite fluorescent substances (such as zinc cadmium sulfide and calcium tungstate). ) to produce visible fluorescence. This feature is the basis of fluoroscopy.

Photographic effect:

X-rays can cause photochemical reactions of many substances, such as irradiating a film coated with silver bromide, and generating a latent image after exposure. After developing and fixing, the silver ions in the exposed silver bromide are reduced to metallic silver, which is deposited on the film and appears black. If it is not exposed to light, it will show the transparency of the film base. This characteristic is the basis of X-ray imaging.

Ionization effect:

X-rays can ionize atoms and molecules through any substance, and will also cause biological changes, that is, biological effects, after entering the human body. It is the basis of radiation protection and radiotherapy.