Varian Clinac iX, a linear gas pedal radiotherapy device with image guidance, integrates image guided radiotherapy (IGRT), intensity modulated radiotherapy (IMRT), and three dimensional conformal radiotherapy (3DCRT) to provide precise radiotherapy to tumors. It is the most advanced special equipment for tumor radiotherapy in the world. The difference between IMRT and conventional radiotherapy can be summarized as “four best”: 1) the largest dose of radiation within a certain range of the tumor target area; 2) the smallest dose of radiation to the normal tissues around the tumor target area; 3) the most uniform dose distribution within the tumor target area; 4) the most accurate positioning and irradiation of the tumor target area. The advantages of precise radiotherapy are “high precision, high dose, high efficacy and low damage”. The equipment is suitable for general radiotherapy and precise radiotherapy for benign/malignant tumors in various parts of the body.