Malignant tumor is one of the major diseases that seriously endanger human health and human life. It can be used for the treatment of many kinds of malignant tumors, especially those that cannot be removed surgically or completely or multiple metastases, and can be applied repeatedly to achieve the best therapeutic effect. The principle of radionuclide therapy is to deliver radionuclides or le markers to the lesioned tissues or cells, or the lesioned tissues and cells can actively take up the radiopharmaceuticals, so that the radionuclides are concentrated in large quantities in the lesioned areas and the irradiation dose is mainly concentrated in the lesion, using the biological effect of ionizing radiation of β-particles emitted from the radionuclides to act directly or indirectly on biological macromolecules, such as nucleic acids and proteins. The biological effect of ionizing radiation emitted from nucleophores is used to directly or indirectly act on biological macromolecules, such as nucleic acids and proteins, to break their chemical bonds, resulting in changes in their molecular structure and function, and to inhibit or kill diseased cells for therapeutic purposes. In general, the sensitivity of normal cells to radionuclides varies, the greater the cell division activity, the stronger the ability to concentrate radionuclides, the more sensitive to radiation, the greater the radiation damage. While the radiation destroys or inhibits the diseased tissue, the damage to normal tissue is milder. Features of radionuclide internal irradiation therapy Targeted The lesion tissue can concentrate the radionuclide with high specificity, good efficacy and low toxic side effects. Continuous low dose rate irradiation The radionuclide concentrated in the lesion emits radiation during the decay process to irradiate the lesion cells at a continuous low dose rate, so that the lesion tissue has no time to repair. High absorbed dose The absorbed dose of internal irradiation therapy is determined by the effective half-life of the radionuclide in the lesion. The earliest and most widely used radionuclide therapy is in thyroid diseases, such as hyperthyroidism (commonly known as hyperthyroidism), thyroid cancer and its metastases, and other items that have been carried out with good results are bone metastases of cancer and pheochromocytoma. Particle nuclide implantation is a new technology in recent years, which can be implanted under direct surgical view or percutaneously by puncture, and can be used for a variety of tumors, with more than 80% of the symptoms being controlled and the mass shrinking. 1.131I treatment for hyperthyroidism Principle: The thyroid gland has a high 131I uptake function, and the amount of 131I uptake in hyperfunctional thyroid tissue is even higher. 131I decay mainly emits beta particles, which have an average range of 1mm in the tissue and generally have no effect on the surrounding normal tissues, and can be used to “excise” part of the thyroid tissue. It is possible to use radioactivity to “excise” part of the thyroid tissue while preserving a certain amount of thyroid tissue for therapeutic purposes. Indications: Poor efficacy of ATD or multiple relapses; long duration of disease or middle-aged or elderly patients (especially those with high risk factors for cardiovascular disease); allergy or other adverse reactions to ATD; contraindication to surgery or high risk of surgery; history of neck surgery or external irradiation; hyperthyroidism combined with hepatic impairment; hyperthyroidism combined with leukocytopenia or thrombocytopenia; hyperthyroidism combined with heart disease; other special types of hyperthyroidism. Contraindications: Pregnant and lactating patients. After the normal thyroid tissue is removed, the well-differentiated thyroid cancer tissues (papillary thyroid cancer and follicular carcinoma) can take in sufficient amount of 131I and use the radiation generated by the decay of 131I to destroy the tumor cells, so as to inhibit the growth of recurrence or metastases. It is used to inhibit the growth of recurrence or metastasis. Indications: Except for DTC with all cancer foci 3.0×109/L; good general condition. Contraindications: Pregnant and lactating patients; patients whose trauma has not completely healed after thyroid surgery; patients with WBC below 3.0×109/L; patients with severe impairment of liver and kidney function. Nuclear therapy for metastatic bone tumors Principle: The radiopharmaceuticals used for the treatment of metastatic bone tumors have good affinity with bone tissues, and more osteophilic radiopharmaceuticals can be taken up at sites with active metabolism of bone tissues. Bone metastasis tumor lesions can concentrate a large amount of radiopharmaceuticals because the bone tissue is destroyed and the osteogenic repair process is very active. The radioactive drug emits β-rays during the decay process, which can produce ionizing radiation effect to destroy tumor cells to achieve pain relief and suppress or destroy bone metastases. Currently, 89 strontium chloride (89SrCl2) and 153 samarium-ethylenediaminetetramethylphosphonic acid (153Sm-EDTMP) are often used in clinical practice. Indications: 1.Bone metastases diagnosed by clinical and bone imaging, bone imaging shows that the lesions are radiologically concentrated; 2.Metastatic bone tumor with bone pain; 3.Primary bone tumor failed to be surgically removed or residual, or with bone metastases; 4.WBC ≥ 3.5×109/L, platelets ≥ 80×109/L. Contraindications: Bone imaging shows that the metastases are radiologically concentrated Osteolytic changes in the “cold zone”; patients with severe bone marrow, liver and kidney dysfunction; patients who have undergone cytotoxic treatment recently (within 6 weeks). V. Radioactive particle implantation therapy Principle: Radionuclides with certain activity are marked on colloids, microspheres or metal wires, enclosed in a titanium alloy shell to make granular particles of very small volume, which are implanted into tumor entities or tumor-invaded tissues by surgery or with the help of imaging guidance to kill tumor cells or inhibit tumor growth by using radionuclide rays. Currently, the commonly used radionuclide is 125I particles. Indications: Multiple primary malignant tumors; extensive tumors that cannot be completely removed by invading surrounding tissues; extended and spreading parts of local or regional cancer, especially invading important tissues that are difficult to be surgically removed; local lesions that remain after external irradiation treatment due to dose or tolerance; isolated metastatic or recurrent cancer foci. Contraindications: tumors invading large blood vessels or near large blood vessels with infection; tumors in ulcerative deterioration; tumors with brittle quality, rich blood vessels and multiple sources of blood supply and certain sarcomas; cranio-cerebral tumors with extensive metastasis or subarachnoid implantation and intracranial hypertension; patients who are estimated to be unable to survive only the efficacy of treatment. Precautions for radionuclide therapy Pre-treatment preparation: 1. Health education. Inform patients and family members of the advantages and disadvantages of radionuclide therapy and possible toxic side effects and related complications, patiently and meticulously do a good job of explaining that radionuclide therapy is simple, safe and effective, relieve patients’ concerns, do a good job of health promotion, instruct patients and family members to do a good job of radiation safety protection, sign the relevant informed consent, obtain the trust, understanding and cooperation of patients and family members. 2. Diet. Some foods or drugs can affect the function of radionuclide uptake by the lesion, so they should be avoided before treatment. 131I foods rich in iodine (such as seafood like kelp and nori, salt first after frying before consumption) and iodine-containing drugs (such as iodophor, iodine contrast agent, thyroxine tablets and some traditional Chinese medicines like kombucha and shellac) should be prohibited for more than 4-6 weeks before treatment. Chemotherapy or radiotherapy should be stopped for at least 2-4 weeks and a low-calcium diet should be given for 1 week before nuclear therapy for bone metastases. 3. Pre-treatment examination. Before nuclear therapy, check the blood routine, white blood cell and platelet count, and liver and kidney function tests. Before radioactive iodine 131 treatment, check thyroid function and ultrasound of the neck, etc. Before implantation of 125I particles, the relationship between the mass and the surrounding tissues and organs should also be understood. 4. Radiation protection: Due to the high dose of 131I used in the treatment of DTC patients, they should be isolated in a nuclide treatment ward with special protective measures for about one week after taking the drug. Before the nuclide treatment, give a detailed explanation to patients and their families about precautions, instruct patients to handle excretion correctly, avoid contact with children and pregnant women, and minimize visits. Adverse reactions and treatment: 1. Gastrointestinal reactions: Some patients may experience weakness and poor appetite after treatment, and a few patients may experience vomiting and headache, which usually disappear on their own without special treatment. However, vomiting after taking the drug will make 1311 uptake not reach the expected effect, so 1311 treatment to prevent vomiting symptoms is the focus. 2, bone marrow suppression: A few patients may observe a transient decrease in white blood cells and platelets, so it is recommended that peripheral blood changes should be monitored weekly after treatment until they return to normal. 3. Local reactions: Taking high dose radioactive iodine 131 may cause neck swelling, laryngeal edema, salivary gland swelling and pain, etc. Patients are advised not to squeeze the neck; after treatment, they can take VitC or acidic candy and chew gum regularly to promote saliva secretion and reduce salivary gland irradiation; take prednisone to reduce laryngeal edema, neck swelling and pain and other local reactions; drink more water after taking the drug and keep defecating once a day to reduce pelvic and abdominal cavity irradiation. 4. Aggravated pain: At the initial stage after the treatment of bone metastasis cancer, there may be transient pain aggravation, which lasts about 2-4 days and becomes “rebound phenomenon” or “bone pain flicker”. Patients should be informed immediately that this is a normal reaction after treatment, and the motivation for the increased pain should be explained to eliminate their fear and anxiety, and analgesic treatment should be given if necessary. After radioactive iodine 125 particle implantation, a small number of patients may have pain, which can be treated symptomatically such as analgesia, and family members can also chat with patients to distract them and reduce their symptoms. 5.Fever: Fever occurs in a few patients after particle implantation and bone metastasis treatment, mostly low or moderate fever, which mostly returns to normal after symptomatic treatment, pay close attention to the change of body temperature, ask patients to drink more water, closely observe the change of vital signs, and give physical cooling and drug cooling treatment when necessary. 6, pulmonary embolism: radioactive particle implantation has fewer adverse reactions, pulmonary embolism is the most serious complication after particle implantation, the particle floating out can enter the larger blood vessels near the implantation organ, flow with the blood and enter the lungs. Therefore, the patient’s breathing should be closely observed after surgery, and the patient should be instructed to avoid kneading the implantation area as much as possible after surgery. If there is any discomfort such as dyspnea or chest pain, absolutely rest in bed, do not take deep breaths, avoid violent coughing and forceful activities, and report to the physician or seek medical treatment as early as possible. Discharge instruction: At the time of discharge, advise the patient to eat a high-calorie, high-protein, high-vitamin diet, and to exercise appropriately according to the physical condition to improve the immunity of the body, and instruct the family members to do their own protection. After discharge, if there is any discomfort, return to the hospital in time; if there is no special change in the condition, review after 1 month or 3-6 months. Patients with differentiated thyroid cancer treated with 131I removal therapy after surgery and some patients with hyperthyroidism treated with 131I need to take thyroxine replacement therapy for life, and patients are instructed to take the medication on time.