This is also known as inter-tissue implantation therapy with radioactive particles. The radioactive particles are placed directly inside the prostate tumor through a precise positioning called the “3-D treatment planning system” to treat prostate cancer. In addition, radioactive particles can be permanently implanted in areas of the tumor that cannot be surgically removed during surgery and in lymph nodes that may have metastasized, to achieve better results than surgery alone. Currently, the most commonly used procedure in China is trans-perineal implantation under rectal ultrasound guidance. This type of radioactive source implantation needle is visible, which improves the accuracy of placement and reduces surgical complications and costs. During the procedure, the patient is placed in a lithotomy position and the transrectal ultrasound probe is placed in the rectum and secured in a template or fixator with a stepper. A template with a pre-puncture point is attached to the stepper. This ensures that the prostate images are acquired with accuracy and reproducibility during the procedure. By using computer software with an ultrasound device, ultrasound images can be superimposed on the template. A 17- or 18-gauge puncture needle is inserted into the prostate through the template. The transverse or longitudinal image of the ultrasound identifies the position of the puncture needle, and the sealed metal particles containing the radioisotope are implanted into the prostate as the puncture needle is withdrawn.