Radioactive particles are small short rods made of radionuclides that kill tumor cells by putting them into a metal shell and sealing them, which can treat malignant tumors by irradiating tumor cells at close range when buried in the body. It includes brief insertion therapy and permanent particle implantation therapy. Permanent particle implantation therapy is commonly used with 125 iodine (125I) and 103 palladium (103Pd), of which 125I is the most commonly used, with a half-life of 59.6 days. Short-term implantation therapy is commonly used with 192 iridium (192Ir). Studies have shown that the choice of isotope has no effect on tumor control. There are several commonly used methods of permanent radioactive particle implantation. One of the more common is the method described by Blasko in the USA, where transrectal ultrasound images are applied for radiotherapy planning calculations prior to implantation, and these images are subsequently used for intraoperative radioactive particle localization. The calculation of the dose distribution of radioactive particles is performed intraoperatively, and the use of advanced computer software allows for dose optimization. High-dose rate brachytherapy techniques have also been used in the treatment of prostate cancer.