What is radiotherapy?

Radiotherapy in a narrow sense generally only refers to the former, which is what people generally call tumor radiotherapy. There are two irradiation methods of radiotherapy: one is long-distance radiotherapy (external irradiation), that is, radiation sources are irradiated at a certain distance from the patient's body, and the rays penetrate the human body to a certain depth to achieve the purpose of treating tumors. This method is the most widely used and the most important; The other is brachytherapy (internal irradiation), that is, the radioactive source is sealed in the tumor or the surface of the tumor, such as the natural cavity or tissue of the human body (such as tongue, nose, pharynx, esophagus, trachea, uterus) for irradiation, that is, the treatment is carried out in the cavity, tissue implantation, model application, etc., which is an auxiliary means for the treatment of cancer with a long-distance 60 Co therapeutic machine or accelerator. In recent years, with the continuous improvement of hospital medical equipment, brachytherapy has gradually become popular. There are three basic differences between internal and external irradiation treatment: ① Compared with external irradiation, the intensity of internal irradiation source is smaller, from a few millicuries to 100 millicuries, and the treatment distance is shorter; ② In vitro irradiation, most of the radiated energy is shielded by collimator and beam limiter, and only a small part of the energy reaches the tissue; In vivo irradiation, most of the energy is absorbed by the tissue; ③ In vitro irradiation, the radiation must pass through the skin and normal tissues to reach the tumor, and the tumor dose is limited by the tolerance of the skin and normal tissues. In order to obtain high and uniform tumor dose, it is necessary to choose different energy rays and adopt multi-field irradiation technology. In vivo irradiation, the radiation reaches the tumor tissue, and the deeper normal tissue is irradiated with a small amount. According to statistics, about 70% cancer patients need radiotherapy in the process of treating cancer, and about 40% pain can be cured by radiotherapy. The role and position of radiotherapy in tumor treatment are increasingly prominent. Radiotherapy has become one of the main methods to treat malignant tumors. Radiotherapy is the use of X-rays, gamma rays and other rays to treat human pathological tissues.