Radiotherapy, also known as radiotherapy, is a means of treating tumors by using radiation (X-rays, electrons, gamma rays, proton rays, neutron rays, etc.) and is one of the three major treatments for malignant tumors (surgery, radiotherapy and chemotherapy). According to WHO, more than 70% of malignant tumors require radiotherapy in different stages of treatment. About 45% of all malignant tumor patients can survive long-term after treatment, of which, surgery contributes 22%, radiotherapy 18% and chemotherapy only 5%. People feel unfamiliar with radiotherapy, and even non-radiotherapy doctors do not know much about radiotherapy. The main reason is that people always associate radiotherapy with nuclear radiation and nuclear bombs, and think radiotherapy is a horrible treatment modality. In fact, any treatment is a double-edged sword, if used well, it is a cure, but if not used well, it will bring more side effects. Radiotherapy is a scientific, rational and controlled use of radiation to serve patients, and it is a highly scientific and technical profession that requires specialized radiologists, physicists, technicians and other personnel. The radiotherapist plays a leading role and is responsible for the entire treatment process and post-treatment follow-up of the patient. Secondly, due to the complexity of radiotherapy technology and expensive equipment, its operation and maintenance require professional and highly skilled personnel, and a radiotherapy equipment can easily cost tens of millions of dollars, or even hundreds of millions of dollars, requiring a large amount of capital and human investment. With the development of our country and the progress of our society, we have the ability to enjoy the benefits brought by high-tech development. In the past 10 years, with the rapid development of computer technology, radiotherapy has realized the transformation from conventional radiotherapy to modern radiotherapy. The characteristics of modern radiotherapy: high precision, high dose, high selection, high efficacy, short treatment course, and micro-invasive. The classic representatives are rotary intensity modulated arc radiotherapy system (VMAT), image guided radiotherapy (IGRT), spiral tomography radiotherapy system (TOMO), etc. Role of radiotherapy 1. Urological tumors: Taking prostate cancer as an example, radiotherapy is the main treatment for prostate cancer. The efficacy of radiotherapy for patients with intermediate – low risk prostate cancer is comparable to that of surgery, while the toxic side effects are less, and there are no adverse effects such as urinary incontinence and sexual dysfunction brought about by surgery. High-risk or locally progressive prostate cancer is treated with radiotherapy combined with endocrine therapy, which is the currently accepted treatment principle in the medical field. Especially with high technology such as VMAT and IGRT, the treatment of prostate cancer has been upgraded with more accurate radiotherapy, higher dose, better efficacy and less trauma. And it is possible to achieve large split radiotherapy for prostate cancer, so that patients can receive a better dose of radiotherapy in a shorter period of time, which greatly shortens the treatment time while not reducing the efficacy. 2.Lung cancer: Take early lung cancer as an example, early lung cancer can be cured. Before the emergence of modern radiotherapy, surgery was the only means to treat early lung cancer, but after the emergence of modern radiotherapy, lung cancer patients have another choice, a minimally invasive or non-invasive treatment means. It can eliminate the tumor without incision, anesthesia, lobe removal or even hospitalization, and the therapeutic effect is not lower than that of surgery, while the side effects are lower and the patient is more compliant. 3.Esophageal cancer: Esophageal cancer is one of the most common malignant tumors in China, which is known for its high incidence and difficulty in treatment. The emergence of concurrent radiotherapy has provided hope for many esophageal cancers, which can not only obtain the same survival as surgery, but also avoid the huge trauma of removing the esophagus and lifting the stomach to the chest cavity. 4.Head and neck tumors: Take nasopharyngeal cancer as an example, radiotherapy has the most significant effect in the treatment of nasopharyngeal cancer. The anatomical structure around the nasopharynx is extremely complex and the important organs are dense, so surgery is out of reach, while radiotherapy has obtained very good efficacy in the treatment of nasopharyngeal cancer. No matter early stage or locally progressive nasopharyngeal cancer, the long-term survival after radiotherapy is over 70%. For early-stage laryngeal cancer, radiotherapy has also achieved surprising results, with long-term survival reaching over 90%, while avoiding the problem of possible barriers to occurrence brought about by surgery. 5.Breast cancer: The treatment of breast cancer is a multidisciplinary and comprehensive treatment. In the past, the treatment of breast cancer pushed for enlarged excision. Since the intervention of radiotherapy, the surgery for breast cancer has become smaller and smaller, which has led to the current breast-conserving surgery. It can be said that there is no breast-conserving surgery without radiotherapy. 6.Gynecological tumors: Take cervical cancer as an example, cervical cancer is the second most common tumor in gynecology. For early stage cervical cancer patients, radiotherapy can achieve comparable efficacy with surgery and save the pain and psychological burden of anesthesia, surgery and removal of uterus or cervix; for patients with middle and late stage cervical cancer, surgery cannot be removed, radiotherapy combined with chemotherapy is the standard treatment plan in the world. 7.Liver cancer: Since the birth of modern radiotherapy, radiotherapy for liver cancer has ushered in unlimited hope. Liver cancer cells are very sensitive to radiation, and modern radiotherapy can give a high dose to the tumor lesion without affecting the function of other normal liver tissues. Whether it is early-stage liver cancer or intermediate or advanced liver cancer, radiotherapy can provide excellent treatment results. For some tumors near large blood vessels or important organs, surgery and ablation are very tricky and difficult to eradicate, while radiotherapy can achieve the purpose of eradicating tumors non-invasively or minimally invasively. 8.In addition, radiation therapy has become the standard treatment for rectal cancer, gastric cancer, lymphoma, central nervous system tumor, pediatric tumor, bone and soft tissue sarcoma, and metastases in various parts of the body. Radiation therapy technology 1.Vertical intensity modulated arc radiotherapy system (VMAT): This is the most advanced precision radiotherapy technology in the world, which not only can achieve coplanar or non-coplanar intensity modulated radiotherapy, but also greatly improve the radiotherapy efficiency. It allows the physician to adjust the volume distribution within the tumor target area to achieve inhomogeneous irradiation between the tumor surface and various points inside the tumor. VMAT allows the frame to rotate and the multi-leaf grating to move continuously to achieve treatment while rotating, so the treatment efficiency will be greatly improved and the patient’s discomfort during treatment will be minimized. 2.Image guided radiotherapy (IGRT): As the name implies, IGRT is the basis of precise radiotherapy, which can correct the errors caused by pose, organ movement and tumor volume changes during radiotherapy and realize precise radiotherapy. And it makes large-segment radiotherapy for malignant tumors widely available, especially for stereotactic radiotherapy (SBRT) for prostate cancer and early lung cancer is of great significance. 3.Large aperture 4D-CT: Large aperture 4D-CT is a special CT for radiotherapy; firstly, the large aperture can facilitate CT simulation and positioning of patients in different positions; secondly, it can dynamically capture the organ movement caused by respiratory motion, so that there will be no leakage during radiotherapy for lung cancer, liver cancer and other tumors due to respiratory motion. 4.3D Conformal Intensity Modulated Radiation Therapy: This is a kind of advanced precise radiotherapy technology in the world at present. It can select multiple irradiation fields from three-dimensional direction (three-dimensional) so that the shape, size and dose distribution of each field can be adapted to the projection of the tumor in that direction, and the radiation can be tightly fixed to the tumor (conformal) and the dose of irradiation to the surface and internal points of the tumor can be the same.