Intensity modulated radiation therapy is an emerging radiation technology for tumors developed at the end of last century and this century. The biggest difference with the previous radiotherapy is that it applies a lot of modern technology to make the target area, especially the irregular target area, obtain a dose distribution consistent with the shape of the target area, even if the three-dimensional shape of the radiation high dose is suitable with the tumor shape to achieve the basic consistency and reduce the dose to the surrounding normal tissues, so as to improve the efficacy and protect the normal tissues. Protect normal tissues. Intensity-modulated radiotherapy can be used for nasopharyngeal cancer, lung cancer, esophageal cancer, prostate cancer, pancreatic cancer, brain tumor, breast cancer, etc. The advantages of conformal radiotherapy include: (1) minimizing the radiation dose to the surrounding normal tissues and reducing radiation damage; (2) increasing the radiation dose and total dose of each radiotherapy treatment, which can improve the local control rate of some tumors; (3) giving different radiation doses to the target area at the same time; (4) irradiating several metastatic lesions at the same time, such as multiple liver metastases and brain metastases, etc.