Radio frequency, usually abbreviated as RF. Represents the electromagnetic frequency that can be radiated into space, ranging from 300 kHz to 30 GHz. Radio frequency is abbreviated as RF current, which is the abbreviation of high frequency AC electromagnetic wave. Alternating current that changes less than 1000 times per second is called low-frequency current, and that that changes more than 10000 times is called high-frequency current, and radio frequency is such high-frequency current. Cable TV system adopts radio frequency transmission mode. In electronic theory, when current flows through a conductor, a magnetic field will be formed around the conductor. Alternating current passes through a conductor and forms an alternating electromagnetic field around the conductor, which is called electromagnetic wave. When the frequency of electromagnetic wave is lower than 100khz, the electromagnetic wave will be absorbed by the surface and cannot be effectively transmitted. However, when the frequency of electromagnetic waves is higher than 100khz, electromagnetic waves can propagate in the air and be reflected by the ionosphere at the outer edge of the atmosphere, forming a long-distance transmission capability. We call high-frequency electromagnetic waves with long-distance transmission capability radio frequency, and radio frequency technology is widely used in the field of wireless communication.
Classification of radio frequency technology
Automatic identification technology
Automatic equipment identification technology is a new technology that is developing rapidly in the world at present. Its English name is Automatic Equipment Identification (AEI). The basic idea of this technology is to realize people's automatic identification and management of objects or equipment (people, goods) in different States (moving, static or harsh environment) by adopting some advanced technical means. At present, the most widely used automatic identification technology can be roughly divided into two aspects: optical technology and radio technology. Among them, the products widely used in optical technology are: bar codes and cameras. These two products have been widely used in people's daily life and are widely known. For example, bar codes are used for commodity management, and cameras are used to capture illegal vehicles.
Radio frequency identification technology
Radio frequency identification technology can be divided into low-frequency system and high-frequency system according to the different frequencies it uses. According to whether the battery power supply is installed in the electronic tag, it can be divided into active system and passive system. The information injected by electronic tags can be divided into three categories: integrated circuit solidification type, field wired rewriting type and field wireless rewriting type; According to the technical means of reading electronic tag data, it can be divided into three categories: broadcast emission, frequency doubling and reflection modulation.
1. Generally speaking, the low-frequency system means that its working frequency is less than 30MHz, and the typical working frequencies are: 125KHz, 225KHz, 13.56MHz, etc. Radio frequency identification systems applied in these frequency points are usually supported by corresponding international standards. Its basic characteristics are low cost of electronic tags, less data stored in tags, short reading distance (in passive case, the typical reading distance is 10cm), various shapes of electronic tags (card shape, ring shape, button shape and pen shape), and weak directivity of reading antennas.
2. High-frequency system generally means that its working frequency is greater than 400MHz, and the typical working frequency bands are: 9 15MHz, 2450MHz, 5800MHz, etc. High frequency systems are also supported by many international standards in these frequency bands. The basic characteristics of high-frequency system are high cost of electronic tag and reader, large amount of data stored by tag, long reading distance (up to several meters to more than ten meters), good adaptability to high-speed movement of objects, generally card-shaped, and strong directivity of reading antenna and electronic tag antenna.
3. Active electronic tags are equipped with batteries, which generally have a long reading distance, but the disadvantage is that the battery life is limited (3~ 10 years); There is no battery in the passive electronic tag. After receiving the microwave signal from the reader (reading device), it converts part of the microwave energy into direct current for its own work, which is generally maintenance-free. Compared with active system, passive system has some limitations in reading distance and adapting to the moving speed of objects.
Application of radio frequency in medicine
What is RF wrinkle removal?
It is a non-invasive treatment and one of the safest and most effective cosmetic wrinkle removal methods at present.
Principle of RF wrinkle removal
Radio frequency waves penetrate the barrier of epidermal basal melanocytes, so that the collagen fibers in the dermis layer are heated to 55℃-65℃, and the collagen fibers contract, which tightens the loose skin wrinkles, thus achieving the purpose of beauty and wrinkle removal.
Characteristics of RF wrinkle removal
Features 1: high efficiency. Experiments show that RF wrinkle removal can effectively stimulate collagen reorganization, tighten skin and reduce wrinkles, with high satisfaction after treatment.
Feature 2: Safety. RF wrinkle removal system can protect epidermis, achieve satisfactory results of safety and efficiency, and is safer than other non-invasive treatments. In addition, there is no recovery period after treatment, and patients can immediately resume their daily life, eliminating other necessary preventive measures after treatment.
Feature 3: Durability. After treatment, the skin will improve every day because of the continuous production of new collagen. And will achieve more significant and satisfactory results in about 4-6 months.
Radiofrequency ablation
Radio frequency refers to radio frequency, but it does not belong to the frequency band division in radio communication. Because the radiation performance is very low in this frequency range, it is rarely used in communication equipment, and its effect on organisms is mainly thermal effect. When the current frequency of RF reaches a certain value (>; 100kHz), which causes the movement of charged ions in the tissue, that is, friction heating (60~ 100℃). The common frequency of RF ablation equipment is 200~500kHz, and the output power is 100 ~400W.
ingredient
All RF thermal ablation depressions are composed of five parts: electric generator, measurement and control unit, electrode needle, skin electrode and computer. The system forms a closed loop, connecting the electrode needle with the skin electrode of the patient. The measurement and control unit automatically adjusts the output power of radiofrequency ablation by monitoring the changes of parameters such as impedance and temperature of tumor tissue, so that tumor tissue can rapidly produce large-scale coagulative necrosis. Ablation electrode is the core component of radiofrequency ablation instrument, because it directly affects the size and shape of coagulation and necrosis. The ideal shape of solidification zone should be spherical or oblate. Under the guidance of B-ultrasound or CT, the multi-needle electrode is directly pierced into the diseased tissue block, and the temperature in the tissue can exceed 60℃ with radio frequency electrode needle, resulting in cell death and necrosis area. If the local tissue temperature exceeds 100℃, the parenchyma around the tumor tissue and organs will solidify and necrosis, and a large area of spherical solidified necrosis area will be produced during treatment. In addition to the coagulation and necrosis area, there is also a hyperthermia area at 43~60℃, where cancer cells can be killed and normal cells can be restored.
The principle of radiofrequency ablation;
Radio frequency introduction
Radio frequency is a kind of high-frequency vibration with a frequency of 6.5438+0.5 million times per second. The human body is a complex structure composed of many organic and inorganic substances, and the body fluid contains a lot of dielectrics, such as ions, water, colloidal particles and so on. The human body mainly relies on ion movement to conduct current. Under the action of high frequency alternating current, the direction of ion concentration changes back and forth with the direction of current by plus or minus half a period. Under the high-frequency oscillation, the ions between the two electrodes move rapidly along the power line direction, and gradually change from the moving state to the vibrating state. Because of the different sizes, masses, charges and moving speeds of various ions, the ions rub against each other and collide with other particles to produce bio-thermal effects. Because of the poor heat dissipation of tumor, the temperature of tumor tissue is higher than that of its adjacent normal tissue, and cancer cells are sensitive to high heat, which can kill cancer cells without side effects.
heat effect
The therapeutic mechanism of RF therapeutic instrument with ablation and cutting function is mainly thermal effect. Radio frequency waves are essentially electromagnetic waves within a specific range. At present, most medical RF frequencies are 200 kHz-750 kHz. The working frequency of radio frequency therapeutic instrument (endoscope) is 400KHz. When radio frequency current flows through human tissues, the positive and negative ions in cells move rapidly due to the rapid change of electromagnetic field, so their friction with other molecules and ions in cells heats up the focus, which makes the water inside and outside the cells evaporate, dry, contract and fall off, resulting in aseptic necrosis, thus achieving the purpose of treatment.
Radiofrequency ablation treatment process
Under local anesthesia, 3 ~ 4 electrode catheters were sent to coronary sinus, high right atrium, His bundle and right ventricle through femoral vein and subclavian vein to stimulate atrium and ventricle to induce tachycardia in line with clinical conditions, locate the origin of tachycardia, and then the electrode catheter for ablation was sent to the located origin and connected to the external RF generator. Repeated electrophysiological examination after discharge, if tachycardia can not be induced and there is no attack in clinical follow-up, it means that ablation is successful.
Indications for radiofrequency ablation:
1, solid tumor
The radio frequency generated by the radio frequency generator is emitted to the center of hysteromyoma at a fixed point under the guidance of B-ultrasound, so that the hysteromyoma is heated to above 60℃, and finally dehydrated, coagulated, denatured and necrotic, and then gradually absorbed and excreted by the body, so as to achieve the purpose of eliminating hysteromyoma without surgery and preserving the uterus. Radiofrequency biological thermal effects have the following effects on uterine fibroids: 1) cell death of fibroids; 2) Vascular injury and blood supply occlusion; 3) nerve destruction in myoma; 4) the 4)pH value is reduced; 5) The hormone receptor is destroyed; 6) The immune system specially activates the phagocytic system, and finally the tumor shrinks and disappears.
2. Common gynecological diseases
The biological thermal effect of radio frequency makes the endometrium have the following functions: while scraping the endometrium, the basal layer is ablated to a shallow basal layer of 2-3 mm, so that it falls off and is discharged, thus achieving the purpose of treating functional uterine bleeding, and has no effect on the myometrium structure and ovarian function. Because radiofrequency ablation is completed under the guidance of B-ultrasound, the operation is intuitive and easy to observe, and it does not require laparotomy and will not remove any normal tissues, thus completely retaining the integrity of the uterus and pelvic structure. It is another new breakthrough in the history of gynecological minimally invasive surgery. Radiofrequency ablation can not only effectively eliminate fibroids, but also be used for functional uterine bleeding, cervical erosion, condyloma acuminatum and other diseases. After years of clinical research, the effect of radiofrequency ablation in gynecology is extremely ideal. Clinical data show that when hysteromyoma is less than 5 cm, the one-time cure rate is 97.83%. The one-time cure rate of uterine bleeding reached 965438 0.58%. The cure rate of cervical erosion was 97.03%.
3. Radical treatment of arrhythmia
Radiofrequency ablation therapy instrument for cardiac catheter RF ablation is a method to treat arrhythmia by introducing RF current (a kind of high-frequency electromagnetic wave) into the heart through cardiac catheter to ablate local myocardial cells in specific parts, so as to ablate the reentrant ring or eliminate abnormal lesions. It is a method that can achieve radical cure of arrhythmia. Radiofrequency catheter ablation for tachyarrhythmia was born in the mid-1980s, and it was introduced in China in the early 1990s. At present, this technology has been carried out in major hospitals across the country and tens of thousands of operations have been completed. Thousands of patients with tachycardia completely got rid of the disease and returned to normal life, study and work.
The most widely accepted new technology for doctors and patients.
It can be said that radiofrequency ablation is a new technology that develops rapidly and is widely accepted by both doctors and patients. At present, radiofrequency ablation technology is quite mature, and its indications have developed from simple paroxysmal supraventricular tachycardia (mainly atrioventricular accessory pathway and atrioventricular node dual pathway) to idiopathic ventricular tachycardia, frequent ventricular premature beats, atrial flutter, atrial tachycardia and atrial fibrillation. For common paroxysmal supraventricular tachycardia, the success rate of radiofrequency ablation can reach over 95%, and the postoperative recurrence rate is 1-3%.
How is radiofrequency catheter ablation performed?
Firstly, the electrodes of the cardiac catheter are sent through the internal jugular vein or subclavian vein and bilateral femoral veins for electrophysiological examination to determine the lesion site to be diagnosed and ablated. Then, a special large-head ablation catheter is selected to reach the focus, and RF current is emitted in a short time, and the current power is generally 20-30 watts. After the radio frequency current contacts the myocardial tissue, it produces local relative high temperature, which makes the local myocardial tissue dry and necrotic, and the necrotic myocardial tissue no longer plays the role of conducting electrical signals, thus the arrhythmia can be radically cured. The local damage caused by radio frequency current to myocardium is very limited, the diameter and depth are about 3-4 mm, and it will not affect cardiac function. After intracardiac electrophysiological examination, if ablation is successful, the operation is completed. The operation was performed under local anesthesia. During the whole operation, the patient was awake and could tell the doctor how he felt at any time. After the operation, most patients can go to the fields the next day and be discharged in two to three days. At present, the diseases that can be treated by this technology include: preexcitation syndrome and paroxysmal supraventricular tachycardia, atrial flutter and atrial fibrillation, ventricular tachycardia and atrial tachycardia caused by dual atrioventricular nodal pathways. Among them, the radical cure rate of paroxysmal supraventricular tachycardia can reach over 90%, and the cure rate of ventricular tachycardia is about 50%. Radiofrequency ablation of atrial tachycardia, atrial flutter and atrial fibrillation is in the clinical trial stage. 4. Percutaneous radiofrequency ablation of tumors under the guidance of imaging (CT, B-ultrasound, etc.). ), using radio frequency thermal effect to cause tissue coagulation and necrosis, to achieve the purpose of tumor resection. At present, it has become a new hot spot in many palliative treatments. The main principle of this technology is that the warhead emits medium and high frequency radio frequency waves (460k Hz), which can stimulate tissue cells to oscillate in plasma, and the ions collide with each other to generate heat, reaching 80- 100℃, which can effectively and quickly kill local tumor cells, and at the same time solidify the vascular tissue around the tumor to form a reaction zone, so that it can not continue to supply blood to the tumor, which is beneficial to prevent tumor metastasis. The whole treatment process is controlled by computer and monitored by TV screen. The range of tissue coagulation and necrosis (inactivated tumor area) can reach 5cm×5cm×5cm at a time by radio frequency waves emitted by cluster electrodes. It is the most advanced "guided therapy" and minimally invasive tumor resection.
Multipolar radiofrequency tumor ablation
abstract
It is a new minimally invasive treatment technology for solid tumors that has emerged in recent years. It can save patients from the pain of surgery. Compared with traditional treatment, it has the advantages of high curative effect, less trauma, less pain, quick recovery, no sequelae, no risk and wide indications. Experts at home and abroad praised it as a green treatment technology. The tolerance of tumor cells to heat is worse than that of normal cells. Local heating to 39-40℃ can stop the division of cancer cells, and when it reaches 4 1-42℃, it can kill cancer cells or cause DNA damage, and irreversible cell damage occurs above 49℃. The radio-frequency electrode of the cluster electrode emits high-frequency radio-frequency waves, which excites tissue cells to carry out plasma oscillation, and the generated heat can make the local temperature reach above 90℃, thus killing tumor cells quickly and effectively.
principle
The principle of this technology is that under the guidance of CT and color B-ultrasound, the multipole needle ablation electrode is accurately pierced into the tumor site. Under the control of the electronic computer, the radio frequency ablation instrument introduces the radio frequency pulse energy into the tumor tissue through the multipole needle, so that the tumor tissue generates local high temperature (70℃ -95℃), so as to achieve the purpose of coagulating and necrotizing the tumor tissue and its neighboring tissues that may spread, and to organize or absorb the necrotic tissue in situ.
Indications:
Radio frequency ablation can be used for benign and malignant solid tumors of human organs. At present, liver cancer, lung cancer and breast cancer are widely used in clinic. Primary tumors, metastatic tumors, advanced tumors that cannot be surgically removed, tumors that cannot be completely removed during surgery, and tumor patients who cannot tolerate radiotherapy and chemotherapy can all receive radiofrequency ablation treatment.
The treatment process is simple
The treatment was performed under local anesthesia, and the treatment time was about 1-2 hours. Patients can receive tumor ablation treatment while listening to music and watching TV, and the safety factor is higher. Compared with traditional tumor treatment methods, it has the advantages of low cost, less pain and quick recovery, and can be discharged after 1-3 days of postoperative observation. Combined with chemotherapy or radiotherapy, it can prolong patients' life, improve their quality of life and relieve their pain.
Development history of radiofrequency ablation
Radio frequency ablation has a long history, the technology is constantly improving and mature, and the effect is exact. Radio frequency ablation needle has developed from monopole to multipole, which has a small effective ablation range and poor effect on large tumors, so now there is a cluster multipole needle. It has been proved that if a tumor with a diameter of 7cm is treated with a spherical lesion with a diameter of 4cm, 22 acupoints are needed to completely cover it (it is difficult to operate in practice). It takes 12 points to destroy the focus of a sphere with a diameter of 5cm. In view of this situation, RITA developed a series of RF needles for tumors of different sizes. According to the size of the tumor, the first generation umbrella multipole needle or monopole needle can be selected for tumors with a diameter less than 3cm. However, due to the influence of temperature conduction, the lesions of various unipolar needles are relatively small, and the larger tumors above 3cm will not be completely destroyed. Even if the tumor is injured by unipolar needle for many times, it will not be completely covered, and the normal lung tissue of the patient will also be damaged. For tumors with a diameter of 3cm to 5cm, the second generation multipole needle should be selected. The second generation anchor multipole needle developed by RITA Company in the United States has a maximum ablation diameter of more than 5cm at a time, so it is suitable for all tumors below 5cm. The latest third-generation super needle should be selected for tumors with a diameter of 5cm to 7cm. Studies have proved that if a tumor with a diameter of 7cm is treated with a spherical lesion with a diameter of 4cm, 22 acupoints are needed to completely cover it (it is difficult to operate in practice). It takes 12 points to destroy the focus of a sphere with a diameter of 5cm. RITA recently developed the third generation super multipole needle. The diameter of one ablation is more than 7cm, and the heat conduction is faster and more uniform by using a special injection pump, which greatly shortens the treatment time and has a more accurate effect on treating large tumors. Patients are more relaxed. Generally, local anesthesia and CT scanning are used to locate the tumor, and the tumor is punctured (percutaneously) according to the measured distance and angle. After the electrode was inserted into the tumor center, the electrode was unfolded and radiofrequency ablation was started.
Radiofrequency ablation therapy is suitable for children after three years old.
Radiofrequency ablation therapy is to send the electrode catheter to a specific part of the heart cavity through blood vessel puncture, to find the abnormal conduction path of the heart or the position of ectopic pacing point, and then discharge ablation after fine mapping. Usually, when the number of premature beats per day exceeds 1000, and the lesion position is convenient for catheter operation, radiofrequency ablation can be selected. Children's tachyarrhythmia usually needs radiofrequency ablation surgery, which shows that the heart rate suddenly increases, and the heart rate can be as high as 180-300 beats per minute. There is no radical cure except radiofrequency ablation. Arrhythmia may last for a long time, such as premature beats, most of which will last for seven or eight years, or even more than ten years, and preexcitation syndrome will last for life. When severe arrhythmia occurs, children's activities are limited and their quality of life is poor. If they have recurrent attacks, it will cause heart enlargement and heart function decline for a long time, so we should treat them as soon as possible. Some arrhythmia, such as premature beats, drugs can not shorten the course of disease, but only relieve symptoms. Moreover, the drug is toxic, and if it is used all the time, the child will lose more than the gain. Therefore, only when arrhythmia affects the quality of life and physical condition of children can drug treatment be used, and radiofrequency ablation can also be used under appropriate circumstances. However, because children have small blood vessels and small hearts, it is difficult and risky to implement radiofrequency ablation, so it is necessary to choose carefully. For children with tachyarrhythmia under 3 years old, drug treatment should be taken first as far as possible, and children over 3 years old can consider radiofrequency ablation.