1. In principle, all local solid cancers with tumor diameter below 6.0cm are suitable for iodine 125 particle source treatment. Tumor diameter ≤6.0cm is suitable for iodine 125 particle source implantation; tumor diameter 6.0-10.0cm, with <3 surrounding metastatic satellite foci, can be considered as appropriate; tumor diameter >10.0cm, iodine 125 particle source implantation is prudent. 2.Untreated primary cancer such as prostate cancer, advanced laryngeal cancer. 3.Extended and spread part of local or regional cancer, especially those involving important tissues, which are difficult to be removed. Such as intermediate or advanced pancreatic cancer. 4.Recurrence or metastatic cancer with more isolated lesions, such as pelvic recurrence after Mile’s surgery for rectal cancer. 5.After external radiotherapy, the residual foci of cancer caused by dose or tissue tolerance, etc. 6.Prophylactic implantation in the lymphatic drainage area after radical cancer surgery, such as the implantation in the axilla after radical breast cancer surgery. 7.Particle implantation and external irradiation combined therapy are needed for locally progressive tumors. 8.Particle implantation can be used for the purpose of palliative treatment for locally progressive tumors that are difficult to be controlled by local treatment, or for those with distant metastases but with serious local symptoms. The tumors that can be treated by particle implantation in China include: prostate cancer, intracranial tumor, lung cancer, head and neck tumor, pancreatic cancer, liver cancer, kidney and adrenal tumor. For a large number of patients with advanced tumors, especially liver cancer, gallbladder cancer, pancreatic cancer and central lung cancer, which are difficult to be cured by surgery, brachytherapy with radioactive 125I particle implantation is a good remedial treatment method, and the current hardware such as CT and B ultrasound can meet the needs of radioactive particle implantation.