What happened to the 500 mA X-ray machine in Southwest X-ray Equipment Factory?

Shenzhen United Huayi, the largest manufacturer of metal detectors in Guangdong, provides technical data reference: the nature of X-rays.

(1) physical effect 1. Penetration refers to the ability of X-rays to pass through matter without being absorbed. X-rays can penetrate substances that ordinary visible light cannot penetrate. Because visible light waves are long, their energy is very small. When it touches an object, part of it is reflected, most of it is absorbed by matter, and it cannot penetrate the object. On the other hand, X-rays have short wave length and high energy. When they shine on matter, only a part of them are absorbed by matter, and most of them pass through atomic gaps, showing strong penetration ability. The ability of X-rays to penetrate matter is related to the energy of X-ray photons. The shorter the wavelength of X-ray, the greater the photon energy and the stronger the penetrating power. X-ray penetration is also related to the density of matter. Substances with high density absorb more X-rays and transmit less. Low density has less absorption and more penetration. Using the characteristics of differential absorption, soft tissues such as bones, muscles and fat with different densities can be distinguished. This is the physical basis of X-ray fluoroscopy and photography. 2. When the ionized substance is irradiated by X-rays, the electrons outside the nucleus leave the atomic orbit, which is called ionization. In the process of photoelectric effect and scattering, the process in which photoelectrons and recoil electrons leave their atoms is called primary ionization, and the process in which these photoelectrons or recoil electrons collide with other atoms in the process of traveling is called secondary ionization. In solids and liquids. Ionized positive and negative ions will recombine quickly and are not easy to collect. The forgotten charge in gas is easy to collect, and the X-ray exposure can be measured by ionizing charge: the X-ray measuring instrument is made according to this principle. Due to ionization, gas can conduct electricity; Some substances can react chemically; Various biological effects can be induced in organisms. Ionization is the basis of X-ray injury and treatment. Fluorescence is invisible because the wavelength of X-ray is very short. However, when it irradiates some compounds such as phosphorus, platinum barium cyanide, zinc cadmium sulfide, calcium tungstate and so on. The atom is excited by ionization or excitation. When the atom returns to the ground state, it radiates visible light or ultraviolet light due to the energy level transition of valence electrons. This is fluorescence. X-rays make substances fluoresce, which is called fluorescence. The intensity of fluorescence is directly proportional to the number of x-rays. This function is the basis of X-ray application in perspective. This fluorescence can be used for X-ray diagnosis, making fluorescent screen, intensifying screen, input screen of image intensifier, etc. Fluorescent screen is used to observe the image of X-rays passing through human tissues during fluoroscopy, and intensifying screen is used to enhance the sensitivity of film during photography. 4. Most of the X-ray energy absorbed by hot matter is converted into heat energy, which raises the temperature of the object. This is a thermal action. 5. Interference, diffraction, reflection and refraction are the same as visible light. It has been applied to X-ray microscope, wavelength measurement and material structure analysis. (2) chemical effect 1. The photosensitive effect is the same as that of visible light, and X-rays can make films photosensitive. When silver bromide on the film is irradiated by X-rays, silver particles can be precipitated, and the film will have a "photosensitive effect". The photographic intensity of film is in direct proportion to the number of x-rays. When X-rays pass through the human body, the density of each tissue in the human body is different, the absorption of X-rays is different, and the sensitivity obtained on the exposed film is also different, thus obtaining X-ray images. This is the basis of using X-ray for photographic inspection. 2. Some substances play a coloring role, such as platinum, barium cyanide, lead glass, crystal, etc. Dehydration and discoloration after long-term X-ray irradiation is called coloring effect. (III) Biological Effects When X-rays irradiate organisms, biological cells are inhibited, destroyed or even necrotic, causing physiological, pathological and biochemical changes in organisms to varying degrees, which is called biological effects of X-rays. Different biological cells have different sensitivities to X-rays. Maple Leaf X-ray can treat some diseases of human body, such as tumor. On the other hand, it is harmful to normal health, so we should protect the human body. Biological effects of X-rays < The base of the mortar is caused by X-ray ionization. Because x-rays have hunger on them! Therefore, it is widely used in industry, agriculture, scientific research and other fields, such as industrial flaw detection, crystal analysis and so on. In medicine, X-ray technology has become a specialized subject for diagnosing and treating diseases, and plays an important role in medical and health undertakings.

Third, the application of X-ray in medicine.

(1) X-ray diagnosis The application of X-ray in medical diagnosis is mainly based on its penetrability, differential absorption, photosensitivity and fluorescence. Because X-rays will be absorbed in different degrees when passing through the human body, for example, the amount of X-rays absorbed by bones is more than that absorbed by muscles, so the amount of X-rays after passing through the human body is different. It carries the information of the density distribution of various parts of the human body, and the intensity of fluorescence or light sensitivity caused on the fluorescent screen or photographic film is very different, so shadows with different densities will be displayed on the fluorescent screen or photographic film (after development and fixation). According to the contrast between light and dark, combined with clinical manifestations, laboratory examination results and pathological diagnosis, we can judge whether a certain part of the human body is normal or not. Therefore, X-ray diagnosis technology has become the earliest non-evisceration inspection technology in the world. (II) X-ray therapy X-ray therapy is mainly based on its biological effect. When X-rays with different energies act on diseased cells in human body, the irradiated cells can be destroyed or inhibited, thus achieving the purpose of treating some diseases, especially tumors. (3) X-ray protection When people use X-rays, they find problems that lead to radiation injuries such as hair loss, skin burns, visual impairment of staff and leukemia. In order to prevent X-rays from harming human body, corresponding protective measures must be taken. The above constitute the three links of X-ray application in medicine-diagnosis, treatment and protection.

Four. Brief history of medical x-ray equipment development

Since 1895, X-ray diagnosis and treatment technology has developed rapidly, and the main progress can be divided into the following stages: (1) ion X-ray tube stage (1895 ~ 19 12), which is the early stage of X-ray equipment. At that time, the structure of the X-ray machine was very simple. A gas-containing cold cathode ion X-ray tube with low efficiency is used, and a large induction coil is used to generate high voltage. The exposed high-voltage part has no precise control device. X-ray machine has small capacity, low efficiency, weak penetration, low image clarity and lack of protection. According to the data, it took 40 ~ 60 min to take an X-ray pelvic image at that time, but the skin of the subject was burned by X-ray after taking the photo. (II) Electronic X-ray tube stage (19 13 ~ 1928) With the development of electromagnetics, high vacuum technology and other disciplines, American physicist W.D. Coolidge published in 19 10 that the tungsten wire X-ray tube was successfully manufactured. 19 13 has been put into practical use. Its biggest feature is that the tungsten filament is heated to incandescent state to provide electrons for the tube current, so the tube current can be controlled by adjusting the heating temperature of the filament, so that the tube voltage and tube current can be adjusted independently, which is exactly what is needed to improve the image quality.