Image-guided radiation therapy (IGRT) is a four-dimensional radiation therapy technology, which adds the concept of time factor to the three-dimensional radiotherapy technology and fully takes into account the movement of anatomical tissues during treatment and the displacement errors between treatment sessions, such as respiratory and peristaltic movements, daily positioning errors, contraction of the target area, etc., which cause changes in the distribution of radiation therapy dose and affect the treatment plan. Before and during the treatment, we use various advanced imaging devices to monitor the tumor and normal organs in real time, and adjust the treatment conditions according to the changes in the position of the organs so that the irradiation field can closely follow the target area, so that it can achieve the real sense of precise treatment. 1.About 70% of malignant tumor patients need to receive radiation therapy 2.IGRT (Image Guided Radiation Therapy) is the most advanced tumor radiation therapy technology in the world, which enables patients to obtain accurate images of patient’s body position, important organs and tumor anatomical location in the actual position of tumor radiation therapy, and through real-time online correction and radiation treatment plan revision, patients can obtain the most accurate radiation therapy every time. The patient receives the most accurate radiation treatment every time by real-time online correction and radiation treatment plan revision. It can accurately kill tumor cells while maximizing the protection of normal tumor surrounding tissues, thus significantly improving the radiotherapy and cure rate of tumor patients while improving the quality of life. 3.Indications: IGRT is generally applicable to all kinds of tumors that can be treated by traditional radiotherapy, but it is more suitable for tumors located in complex anatomical locations, tumors adjacent to important organs and tissues, tumors that require high-dose irradiation and recurrent tumors, etc. Such as nasopharyngeal cancer, laryngeal cancer, tonsil cancer, nasal sinus cancer, parotid cancer, intracranial glioma and other malignant tumors in the head and neck, breast cancer; malignant lymphoma, rectal and anal canal cancer, rectal and anal canal cancer, cervical cancer, prostate cancer, liver cancer, stomach cancer and other malignant tumors in the abdomen; and tumors located in the spine. 4.Brief process of treatment: ① clinical diagnosis and staging, determination of radiotherapy plan ② positioning of CT simulation and positioning machine ③ outlining of target area and important tissues and organs ④ physical 3D plan formulation and confirmation ⑤ verification of plan on radiotherapy machine (only IGRT can achieve this) ⑥ turn on the machine after accurate treatment. Repeat the last three steps if necessary.