Technology Introduction: Radiation particle brachytherapy is commonly known as “particle knife or in vivo gamma knife”, which is a minimally invasive treatment method invented by the international medical community for the shortage of tumor surgery and external radiotherapy. The “particle knife” is actually a three-dimensional particle implantation treatment planning system, through which the volume of the target area, the effective dose area and the number of particles needed are calculated. This technology is a high-tech product integrating many disciplines such as radiation physics, radiobiology, tumor radiology and computer application. The main features are: radioactive particle implantation treatment for tumors that are difficult to be completely removed by surgery, subclinical areas of tumors and lymphatic drainage areas that may metastasize, after being implanted into the focal area of the body, the radioactive particles are directly close to the tumor cells and continuously release γ-rays at close range to achieve targeted “blasting” and achieve the effect of overall killing of tumors. The implantation of radioactive particles can be done intraoperatively and can be done at a distance. Particle implantation can be performed intraoperatively or under the guidance of minimally invasive techniques such as thoracoscopy, laparoscopy, ultrasound, CT, etc. It has the advantages of small trauma, target center accuracy, high conformality, low dose continuous irradiation, etc. The local control rate of tumor can reach more than 90%. If external irradiation can be used, tumor regression will be faster, and the external radiation dose can be reduced to reduce the side effects of radiotherapy. Currently, iodine-125 particle implantation has been used as a common method for cancer treatment in China. Treatment principle: The tiny radiation source implanted in the lesion continuously releases low-energy gamma rays to irradiate tumor cells, which continuously damages the DNA double strand of tumor cells, thus causing the tumor cells to lose their proliferation ability and die to achieve the therapeutic effect. Compared with distant external irradiation, the radiobiological characteristics of 125I particles are mainly different in dose rate. There are higher therapeutic ratios: (1) the low dose rate of 125I particles significantly reduces the oxygen enhancement ratio (OER); (2) the high relative biological effect (1.0~1.5 or 1.2~2.0); (3) the long half-life makes the radiation work continuously and improves the killing effect on tumor cells. Because the repair of sublethal damage is more likely to occur with conventional divided external irradiation, the repair of sublethal damage to tumor cells will be inhibited by giving conventional external irradiation at a high dose rate during the continuous low-dose irradiation phase. Indications: 1. Untreated primary solid tumors. 2.Tumors that require preservation of important functional tissues or surgery will involve important organs. 3.Those who are not willing to undergo surgical resection. 4.Preventing local or regional spread of tumor and enhancing the effect of radical treatment, i.e. for prophylactic implantation. 5.Metastatic tumor or postoperative isolated tumor metastases that lose surgical value. 6.Those who cannot be removed surgically. 7.Intraoperative residual tumor or the cutting edge is too close to the tumor. 8.Persons with poor or failed external irradiation effect. 9.Insufficient dose of external irradiation or difficult to upgrade, need to supplement the dose. 10.Palliative treatment of middle and late stage tumor. It is used for a wide range of diseases, including: glioma, meningioma, brain metastasis, nasopharyngeal and orbital tumors, oropharyngeal and oral cancer, metastatic cancer of the neck, lung cancer (primary or metastatic), pleural mesothelioma, breast cancer, esophageal cancer, mediastinal malignant tumors, liver cancer, bile duct cancer, pancreatic cancer, advanced gastrointestinal cancer, kidney and adrenal tumors, prostate cancer, uterine and cervical cancer, bone and soft tissue malignant tumors, etc. It is generally believed that radioactive particle implantation is suitable for slow-growing and well-differentiated tumors. 125I is suitable for tumors with a potential doubling time (Tpot) >10 days and well-differentiated tumors. Studies have shown that the effective treatment time is 120 days with a doubling time (BT) of 5 days and 275 days with a BT of 30 days. Advantages: 1. Iodine-125 seed source is a low activity, low dose, short range, easy to protect sealed type radiation source. 2. It has advantages such as one-time minimally invasive treatment, and patients can be discharged from the hospital in 1~3 days after surgery. 3.The penetration of radiation between tissues (radiation range) is only 1.7cm, so doctors, patients and families do not need special protection and it is very safe to use. 4.No damage or slight damage to the surrounding normal tissues, no systemic toxic side effects. 5.Treatment planning system (TPS) can meet the need of target area dose specific design and can kill the tumor precisely. 6.It can cooperate with other treatment programs, such as chemotherapy and external radiotherapy, to achieve the best therapeutic effect of comprehensive treatment. 7. The intraoperative implantation has minimal trauma to normal tissues, without fully revealing the surgical field and avoiding blind extensive clearance, which can reduce the surgical trauma to a greater extent. 8.The compatibility of radioactive particles is good, the shell is made of peptide alloy, and there is no rejection reflection in human body.