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 uses the thermal effect, photochemical effect, light breakdown and shock wave produced by laser in the process of living tissue propagation. 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. Influence of radioactivity on medicine
The wide application of radiation in the medical field is based on the fact that human tissues will produce some physiological effects after 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. X-ray was applied to clinical medical research only three months after it was discovered. X-ray fluoroscopy is based on different attenuation abilities of different tissues or organs. X-rays with uniform intensity have different intensities after passing through different parts of the body. After the X-rays passing through the human body are projected on the photographic film, different bright and dark images can be observed everywhere after imaging. X-ray fluoroscopy can clearly observe the degree of fracture, tuberculosis focus, the position and size of tumor in the body, the shape of organs and the position of foreign bodies in the body. X-ray fluoroscopy has become one of the basic equipment in hospitals.
1972, G.H.Hounsfield, an electronic engineer of EMI Company in the UK, invented X-CT on the basis of the mathematical method of image reconstruction from data published by American physicist A.M. Comack in 1963, which greatly changed the medical imaging technology. Now X-CT has been widely used all over the world, and has become a major scientific and technological achievement universally recognized. Cormac and Hansfield also won the 1979 Nobel Prize in Medical Physiology. X-CT uses X-rays to penetrate a certain plane of human body and scan line by line. The detector measures and records the intensity values of the rays after penetrating the human body, converts these intensity values into digital signals, and sends them to the computer for processing, sorting and reconstruction. A "slice" diagram of this layer can be displayed on the display. Using X-CT equipment, doctors can see the "slices" of the shapes and positions of various organs and bones on the display, and clearly see the position, shape and nature of the lesions on the image, which greatly improves the accuracy of diagnosis.
The advantage of X-CT is that it can clearly display all sections of human organs and avoid overlapping images. X-CT has high density resolution and certain spatial resolution, and the diagnostic rate of brain tumor can reach 95%. It has a special effect on whether the liver, pancreas, kidney and other soft tissue organs in the abdomen and chest are sick, and it also clearly shows the size and scope of the existing diseased tumors. To some extent, X-CT can also distinguish the nature of tumors. At present, medical X-CT has become one of the most effective means of clinical medical diagnosis. Positron emission tomography (PET) is an advanced nuclear medicine technology with high resolution and physiological nuclide tracing. It is the only display technology of living molecular biology at present, and PET can make early diagnosis of diseases from the genetic level of the origin of life. PET can not only produce radionuclides, but also be used in the research of oncology, neurology and cardiology, providing reliable basis for early diagnosis and curative effect observation of lesions.
Radioactivity is mainly used to treat cancer in clinic. Particle scalpels designed for diseases and parts (such as brain tumors) that are difficult to perform conventional surgery have become popular, among which X-ray scalpels and gamma-ray scalpels are commonly used. Fast neutrons, negative π mesons and heavy ions are also used to treat cancer. They have a good effect on some tumors resistant to gamma rays, but they are expensive and have been used in many laboratories around the world. Secondly, the particle scalpel has a good effect on cerebrovascular disease, trigeminal neuropathy, paralysis, pain, epilepsy and other functional diseases. In addition, medical supplies and instruments can be sterilized by radiation, which has the advantages of thorough sterilization and simple operation.
3. The influence of electromagnetism on medicine
Magnetic resonance tomography is a multi-parameter and multi-nuclear imaging technology. At present, it is mainly the imaging of density relaxation time t and t of hydrogen nuclei (H). Its basic principle is to use electromagnetic waves with a certain frequency to irradiate the human body in a magnetic field. Under the action of electromagnetic waves, the hydrogen nuclei of various tissues in the human body will produce nuclear magnetic vibrations, absorb the energy of electromagnetic waves, and then emit electromagnetic waves. After detecting the electromagnetic signals from the human body by the nuclear magnetic resonance imaging system, the tomographic images of the human body are obtained through computer processing and image reconstruction. Due to the absorption and emission of electromagnetic waves by hydrogen nuclei and the influence of the surrounding chemical environment, the tomographic images of human body obtained from magnetic vibration signals can not only reflect morphological information, but also get pathological information from the images. After comparison and judgment, we can know whether the human tissue at the imaging site is normal or not. Therefore, MRI is considered as a medical imaging technique to study living tissue and diagnose early lesions.
Compared with X- CT and B-ultrasound, MRI can only show the density distribution image of the cross section, while MRI can show the concentration distribution of a certain nuclear isotope or the distribution of a certain parameter (such as relaxation time) in the small cross section. Therefore, MRI can obtain more internal information of human body than X- CT and B-ultrasound, especially for the diagnosis of brain lesions and early tumor lesions.
Because of the existence of electromagnetic field in human body, it can provide important detection basis for the diagnosis of medical diseases. Therefore, EEG and ECG have long been used in the diagnosis of brain diseases and heart diseases, and the corresponding magnetoencephalography and magnetocardiography are more accurate and effective in medical diagnosis, but they have not been widely used in clinical diagnosis due to technical and price reasons. The understanding of magnetocardiogram is late, and it is more effective than X-ray in the diagnosis of lung diseases (such as pneumoconiosis). At present, some developed scientists have regarded it as an important means for the diagnosis of lung diseases.
Because the original X-ray contrast agent (barium meal) is not ideal, people have developed magnetic X-ray contrast agent, which has been used in clinical diagnosis. This is a magnetic flowing liquid, which has a good absorption rate of X-rays. By changing the external magnetic field, it can reach almost any part of the studied body and will not solidify in the body.
Electron microscope is widely used in medicine, which can be used to observe fine structures that ordinary optical microscope can't distinguish. Such as virus in biology, protein molecular structure, etc. The electron microscope is based on the principle that an object is well irradiated by an electron beam to form an image. The electron beam is focused by a magnetic lens (based on the principle of magnetic focusing), and then an electron wave with a shorter wavelength can be generated by accelerating the voltage, and its magnification is dozens or even hundreds of thousands of times that of an ordinary optical microscope.
On the other hand, medical use of electromagnetic principle can improve the internal microcirculation of human body and achieve the effect of treating diseases and health care, such as blood circulation machine and various magnetic therapy instruments; According to the interaction between human body and electromagnetic waves, the thermal effect of electromagnetic energy is used to treat tumors at high temperature and general hyperthermia in medicine. Particle accelerators are used in medicine to generate radiation for diagnosis or treatment, and can also be used to generate radioactive substances injected into the human body for imaging. They are made by using the motion law of charged particles in magnetic field.
4. The influence of acoustics on medicine
Ultrasound is used for diagnosis and treatment in medicine, thus forming ultrasound medicine. Ultrasound is widely used in clinical diagnosis. It mainly uses the good directivity of ultrasonic waves and the physical laws like optical reflection, scattering, attenuation and Doppler effect, and uses an ultrasonic generator to emit ultrasonic waves into the body and spread them in tissues. The acoustic impedance of diseased tissue is different from that of normal tissue. The reflected and scattered waves are received by the receiver, and after processing and imaging, lesions such as A- ultrasound, B- ultrasound and Doppler flowmeters can be diagnosed.
The main difference between B-ultrasound and X-ray fluoroscopy is that X-ray fluoroscopy gives a shadow image projected vertically in the body, while B-ultrasound gives a structural image of a longitudinal section, without overlapping in the direction of the section. Can accurately judge the situation of this road section.
In order to improve the detection level of some small lesions (such as small liver cancer), nonlinear problems in acoustics have attracted people's attention. In recent years, nonlinear parametric imaging has become a research focus of ultrasonic diagnosis, and second harmonic imaging is one of the latest development methods. The application of second harmonic is based on the acoustic contrast agent, which can be injected into the part of the human body to be investigated in advance during ultrasonic diagnosis, which can increase the blood flow information and be beneficial to the display of lesions. Second harmonic imaging has been widely concerned in the diagnosis of coronary artery diseases.
The application of ultrasound in treatment is based on the mechanical effect, warm effect and some physical and chemical effects of ultrasound in human body. There are ultrasonic lithotripsy, ultrasonic hyperthermia for cancer treatment, ultrasonic scalpel and ultrasonic drug penetration therapy. Ultrasound can be used to treat scleroderma, vascular diseases, lumbago and leg pain, mental diseases and many other diseases. There are many kinds of ultrasonic therapy machines used in clinic. In addition, ultrasound is also used for ultrasonic tooth cleaning and ultrasonic weight loss in beauty.
Acoustical microscope is a kind of visible image technology that uses sound waves to obtain microscopic material structure, which is used to observe living bodies in medicine. It is a high-tech instrument integrating acoustics, piezoelectricity, optics, electronics and computer.
At present, the depth and breadth of physics in medical application are being further expanded, and it is often necessary to comprehensively apply a variety of knowledge. For example, acoustic electrotherapy, which can quickly relieve pain symptoms, is a comprehensive use of ultrasound and alternating current. In other aspects, liquid crystal has been used in medical thermography (diagnosis of breast cancer, blood diseases, etc.). ) and other imaging technologies. Techniques such as superconductivity are also applied to medicine.
In a word, physics has greatly promoted the development of medicine, and modern medicine relies more and more on physics. We believe that the Physics Society will get more applications in medicine and make greater contributions to the development of medicine.