When a patient goes to the hospital, the doctor usually starts with a medical history, physical examination, measurement of temperature, respiration, heart rate, blood pressure, and blood tests. Some diseases can be diagnosed from the surface of the body, but diseases in the body cannot be “seen” directly outside the body. For internal conditions, the doctor has to use various medical instruments to diagnose and determine if there is a disease in the internal organs. In this regard, doctors most often use medical imaging technology, i.e., medical imaging equipment to “take pictures” of the internal conditions of the patient’s body and diagnose internal diseases based on the images obtained from the “pictures”. Most of these instruments are used for diagnosis outside the body and are non-invasive to the human body. Therefore, the role of medical imaging is to diagnose the internal health condition of the human body by imaging the internal structure and function of the body with or without damage, giving a three-dimensional, static or dynamic image of the internal body. The internal structure and function of the human body is very complex, and it is not easy to image the internal conditions of the body without damage. This specialized question is called medical imaging. The specialized technology in this area is called medical imaging technology. This is a rapidly developing category of high technology, and the protection of the health of the general public is closely related. The scope of modern imaging includes: conventional X-ray diagnosis, X-ray imaging, DSA digital subtraction angiography, CT (X-ray computerized tomography); ultrasound imaging, including ultrasound; MRI magnetic resonance imaging; nuclear medicine, including ECT. A, X-ray imaging principle: X-rays are high-energy light, which can penetrate many substances, including human tissue. When X-rays pass through the body, they interact with the material inside the body, so that part of the X-rays are scattered or absorbed, and the rest of the X-rays can pass through the body. Because of the different intensity of X-rays passing through different parts of the body, there are different exposures on the X-ray negatives that record the X-rays outside the body, and the “projected” images recorded on the negatives will show different shades of images. In this way, X-rays can be used to fluoroscopy or “film” the human body to diagnose internal lesions. Doctors use these characteristics of X-rays to understand the internal structure of the body. DSA digital subtraction angiography is a new technique that combines an electronic computer with conventional X-ray cardiovascular imaging, and X-ray CT stands for X-ray computed tomography. To perform an X-ray CT scan, the body is irradiated and scanned with X-rays at different angles on the outside of the body. Multiple projection images are obtained, and the computer processing method is used to compose a three-dimensional image. Ultrasound imaging uses the physical properties of ultrasound to interact with the acoustic properties of human tissues and organs to produce information, which is collected and processed to form images. Ultrasound is very popular because of its good intuitive performance, high detection rate, simple operation, rapid diagnosis, and high sensitivity especially for the diagnosis of congenital malformations. It is widely used in obstetrics and gynecology in clinical practice. Ultrasound examination is usually done at 20-22 weeks of gestation, when the whole fetus and its internal structure can be displayed and fetal malformations can be diagnosed. Color ultrasound can also diagnose heart and large blood vessel malformations. MRI imaging principle of medicine is different from X-ray photography and CT, it uses hydrogen protons (H+) in the large amount of water present in the body to image. A single proton is positively charged, and it can also rotate around its own axis, called spin. To make it easier to understand, the spin of a proton is often compared to the gyroscope that many people played with as children. When it is spinning vertically at high speed, a gentle whip will cause it to deviate from its axis and then gradually return to an upright spin. There are countless hydrogen protons in the human body, due to the haphazard direction, the magnetic fields cancel each other and do not show any magnetic field to the outside world, which is like a group of naughty children bickering in the playground and running around, now they need a teacher to arrange them into a queue, so how to turn the hydrogen protons into a queue? If the human body is put into a strong magnetic field then the situation will be dramatically changed, then one of the protons that make up the human body like a small magnetic rod will be temporarily arranged in the direction of the magnetic field to form a large magnetic rod. After arranging the protons into a team, the signal emitted is large enough to be detected by the instrument, processed by the computer and then get the image of the human body. Fourth, nuclear medicine imaging: It is based on the organs with radioactive substances (imaging agent) after ingestion, due to the target organs and non-target organs, normal tissue and lesion tissue there are differences in the distribution, the target organs of selective uptake, selective uptake of lesion tissue cells or no uptake due to the absence of normal function, the distribution of the imaging agent appears significantly different. Firstly, radioactive drug is injected intravenously, and then the nuclear radiation information emitted from the target organ is collected by the instrument, and the image is composed by computer according to the density of the emitted radiation in each part, and this image directly reflects the function of the cells in each part of the organ, so it is called “functional imaging”. For the general public, they are concerned about the cost of the examination, the reasonableness of the examination, the damage to the body and the consequences. There are many factors involved here: doctor-patient relationship, hospital level, diagnostic skill level of the receiving physician, patient income level, etc. For professional imaging physicians involves ‘comparative imaging’. It is necessary for both physicians and patients to understand the principles of comprehensive imaging selection. Sometimes patients do not understand and think that the doctor is abusing the test, here a communication problem is needed, the doctor should explain the imaging lesion for the patient or family to obtain the understanding of the patient or family, here also involves the issue of the patient’s right to know.