Medical physics can be summarized as a branch of physics application, and white is a new frontier discipline formed by applying the theories, methods and technologies of physics to medicine. In other words, the department of medical physics combines physics, engineering, biology and other majors and applies them to medicine, especially radiation medicine or laser medicine. Therefore, medical physics can also cooperate with medical electronics (research on medical equipment), biomedical engineering (application of engineering principles to biology and medicine) and health care physics (analysis and control of radiation injury) to promote the progress of medicine and biotechnology. Its appearance has greatly improved the level of medical education and promoted the improvement and renewal of clinical diagnosis, treatment, prevention and rehabilitation. Its main research contents are: 1, the function of human organs or systems and the physical explanation of normal or abnormal processes; 2. The physical characteristics of human tissues and the influence of physical factors on the human body; 3. Understanding of bioelectricity, magnetism, sound, light, heat, force and other physical phenomena in human body; 4. Physical instruments for medical application (microscope, spectrograph, X-ray machine, CT, isotope and nuclear magnetic resonance vibrator, etc.). ) and physical measurement technology. As an independent discipline, it was formed in 1950s. 1974 International Organization of Medical Physics (IOMP) was established, and 1986 Medical Physics Branch joined the International Organization of Medical Physics in the name of China Medical Physics Society. With the rapid development of modern physics and computer science, people's understanding of life phenomena has gradually deepened, and various branches of medicine have more and more established their theories on the basis of accurate physical science, and the techniques and methods of physics have been more and more widely used in medical research and medical practice. The great contribution of optical microscope and X-ray fluoroscopy to medicine has long been known. Endoscopes made of various optical fibers have eliminated various rigid catheter endoscopes, computers and X-ray tomography (X-CT), ultrasonic scanner (B-ultrasound), magnetic resonance tomography (MRI) and positron emission tomography (PET), which not only greatly reduced the pain and trauma of patients, but also improved the accuracy of diagnosis, and directly promoted the establishment and development of modern medical imaging diagnostics. Every new discovery or technology in physics develops to every new stage, which provides more advanced, more convenient and more accurate instruments and methods for medical research and practice. It can be said that modern medical research and medical units are inseparable from physical methods and equipment. With the development of medicine, the relationship between physics and medicine will become closer and closer. Physics not only provides modern experimental means for the research and prevention of etiology and pathology in medicine, but also provides advanced instruments and equipment for clinical diagnosis and treatment. It can be said that there would be no modern medicine today without the support of physics. 1, the influence of optics on medicine Laser has been widely used in medicine, which makes use of the thermal effect, photochemical effect, light breakdown and shock wave produced by laser in the propagation of living tissues. Ultraviolet laser has been used in microdissection of human chromosomes, which is helpful to explore the molecular basis of diseases. In diagnosis, with the wide application of various laser spectroscopy technologies in the medical field, such as biological tissue autofluorescence, drug fluorescence spectroscopy and Raman spectroscopy, the application in cancer diagnosis and early cataract diagnosis is developing. Laser optical tomography (OT) technology is emerging, which is a new medical diagnostic technology to replace X-CT. In terms of treatment, laser surgery has become a commonly used practical technology. People can choose lasers with different wavelengths to achieve the purpose of high efficiency and little damage. Laser has been used in cardiovascular plaque excision, corneal ablation and plastic surgery, lithotripsy, ophthalmic light perforation, hysteromyoma, skin nevus, laser beauty and photodynamic therapy (PDT). Endoscopes for diagnosis, such as gastroscope, proctoscope, bronchoscope, etc. Are all made according to the principle of total reflection of light on the fiber surface for many times. Medical shadowless lamps and mirrors are also made by using optical principles. Near-field optical scanning microscope can directly study biological specimens and other samples under natural conditions such as air and liquid, and the resolution is over 20nm. It has been used to study single molecules, and is expected to get important applications in the medical field. Elliptically polarized light can be used to identify infectious viruses and analyze cell surface membranes. Holographic microscopy is also widely used in medicine. The influence of radioactivity on medicine Radiation is widely used in the medical field because human tissues will have some physiological effects after being irradiated by radiation. Radiation can be obtained through reactors, accelerators or radionuclides. In the study of etiology and pathology, modern medicine can dynamically study the metabolism of various substances in the body from the molecular level by using radioactive tracer technology, and the problems in medical research are constantly broken. For example, the process of cholesterol biosynthesis, which is closely related to cardiovascular diseases, has been clarified. Now radioactive tracer has become an indispensable and powerful weapon in modern medicine. Radioactivity has been widely used in clinical diagnosis, such as X-ray machine and medical CT. 1895, roentgen discovered X-rays while studying rare gas discharge. Only three months after the discovery of X-ray, it was applied to clinical medical research. X-ray fluoroscopy is based on the fact that different tissues or organs have different attenuation abilities to X-rays. The intensity of uniform X-rays passing through different parts of the body is different. After the X-rays passing through the human body are projected on the photographic film, different bright and dark images can be observed everywhere. X-ray fluoroscopy can clearly observe the degree of fracture, tuberculosis focus, the position and size of tumor in the body, the shape and conclusion of organs.