What is radionuclide internal irradiation therapy?
In contrast to the ordinary external irradiation treatment (radiation from outside the body to the diseased tissue), internal irradiation treatment is the introduction of drugs into the body through oral or intravenous injection, which is different from the ordinary drugs, it is a drug containing radionuclide that can be gathered in the diseased tissue, and then the radionuclide will emit a kind of radiation to kill cancer cells, so as to achieve the purpose of treating the disease.
Is it safe to apply radionuclide internal irradiation treatment?
The radionuclide in internal irradiation therapy can only kill the diseased tissues within 2~3mm, but has no effect on the surrounding normal tissues, just like a missile destroying its target.
Which type of hyperthyroidism is suitable for radioactive iodine-131 treatment?
Graves’ disease (toxic diffuse goiter) and hyperthyroidism in Graves’ disease can be treated with Iodine-131 in the following cases.
1. Abnormal liver function, hypocellularity unsuitable for antithyroid drug (ATD) treatment; allergy to ATD drugs;
2. Relapse after ATD treatment;
3, relapse after surgical treatment or unwilling to operate;
4. Toxic nodular goiter with hyperthyroidism (Plummer’s disease);
5. Chronic lymphocytic thyroiditis with Graves’ disease;
6. Non-toxic goiter can also be treated with iodine-131 from a cosmetic point of view.
What preparations should be made before iodine-131 treatment for hyperthyroidism?
Because iodine-containing foods, medications and antithyroid drugs can affect the uptake of iodine-131 by the thyroid gland, antithyroid drugs and iodine-containing foods and medications should be discontinued for at least 4-6 weeks prior to treatment. Symptomatic treatment of hyperthyroidism symptoms such as panic attacks, low white blood cells and abnormal liver function should be continued during discontinuation of medication.
What tests should be done before iodine-131 treatment for hyperthyroidism?
Before taking iodine-131 treatment, patients with hyperthyroidism should have their thyroid iodine-131 uptake rate measured, biochemical indicators of thyroid function such as TT3, TT4, FT3, FT4 and TSH measured, thyroid antibodies such as A-Tg, A-TPO and TSH receptor antibodies (TRAb, TBII, etc.) measured, thyroid nuclear imaging or ultrasound examination to clarify the size of the thyroid gland and make a preliminary judgment on the nature of thyroid nodules. The nature of the thyroid nodule.
What is iodine-131? What are its medical uses?
Iodine-131 is a radioactive drug, an isotope of iodine, with a physical half-life of 8.04 days; it emits gamma rays for imaging and beta rays for treatment to perform diagnostic and therapeutic functions. Since the synthesis of thyroxine by the thyroid tissue in the body requires the participation of iodine, iodine-131 can accumulate in the thyroid tissue. Beta rays have a range of only 2 mm in the thyroid gland, and the energy it releases can destroy the hyperfunctioning thyroid tissue and shrink the enlarged thyroid gland as if it had undergone an operation. Therefore, iodine-131 is mainly used for the treatment of hyperthyroidism such as Graves’ disease and Plummer’s disease. It is also used for thyroid function measurement, thyroid imaging, and the treatment and follow-up of well-differentiated thyroid cancer and its metastases.
Are nuclear medicine tests of the thyroid gland harmful to the body?
The chemical amount of iodine-131 used for thyroid iodine-131 uptake measurement is very small. The chemical amount of the commonly used radioactive dose of 2 microjuice is 1.6×10-11 grams, which has no effect or harm to human body.
The radioactive drug 99mTcO4-, which is commonly used for thyroid imaging, has a short physical half-life (6 hours). The radioactive dose received by the patient is lower than the dose of a single X-ray chest film.
Can hyperthyroidism treated with iodine-131 cause hypothyroidism?
All three current treatments for hyperthyroidism (anti-thyroid medication, iodine-131, and surgery) can cause hypothyroidism. Therefore, hypothyroidism is not caused only by iodine-131 treatment.
The incidence of hypothyroidism due to hyperthyroidism treated with iodine-131 varies from hospital to hospital, but in China, the incidence varies from 10-25%, and is increasing year by year.
Can patients with hyperthyroidism be treated with both antithyroid drugs and iodine-131?
Since antithyroid medication can affect the uptake of iodine-131 by the thyroid gland and the biochemical measurements of thyroid function, patients should stop taking antithyroid medication (ATD) and avoid iodine-containing food and medication for more than 4 weeks before undergoing nuclear medicine examination and treatment. However, in patients with severe hyperthyroidism, because the general condition of the patient is poor and the therapeutic effect of iodine-131 is slow, in order to prevent aggravation of the disease or the emergence of hyperthyroid crisis, the drug is usually stopped only three days before the determination of the iodine absorption rate of the thyroid gland, and ATD therapy is continued after three days of iodine-131 until iodine-131 takes effect.
Can hyperthyroidism with malignant proptosis recover after iodine-131 treatment?
According to different reports, 15-60% of patients with hyperthyroidism may have proptosis in one or both eyes, either before the onset of hyperthyroidism or during the treatment of hyperthyroidism, or in a few patients after the control of hyperthyroidism or even during hypothyroidism. There is no specific treatment for hyperthyroidism proptosis at home and abroad. Clinical practice shows that most of the hyperthyroidism proptosis is reduced after iodine-131 treatment, but in very few patients, the proptosis is still aggravated after the hyperthyroidism is controlled.
What are the treatment options for hyperthyroidism in Graves’ disease? What are the advantages and disadvantages of each?
There are three main treatment options for hyperthyroidism in Graves’ disease, including internal antithyroid drug (ATD) therapy, 131I therapy in nuclear medicine, and surgical treatment.
Internal ATD treatment is relatively mild and the dosage can be adjusted in time during the treatment. One of the disadvantages of ATD treatment is that it is easy to relapse when the medication is stopped or reduced, and the relapse rate of ATD treatment is reported to be around 40-60%.
The symptoms of hyperthyroidism start to improve about 4 weeks after treatment, and the remission rate of hyperthyroidism can reach 75-80% in about one year. 131I treatment does not cause any damage to liver, kidney function and hematopoietic function. Therefore, it is suitable for the treatment of hyperthyroidism patients with abnormal liver and kidney function or decreased blood cells due to ATD treatment. A major complication of 131I therapy is hypothyroidism, and studies have shown that some patients with hypothyroidism occurring within one year after 131I therapy (early onset hypothyroidism) can return to normal after thyroid hormone replacement therapy; however, patients with hypothyroidism occurring one year after 131I therapy (late onset hypothyroidism) often require a longer period of time or lifelong hypothyroidism. However, hypothyroidism that occurs after one year of 131I therapy (late-onset hypothyroidism) often requires longer or lifelong thyroid hormone replacement therapy. In addition, in patients with hyperthyroidism with severe proptosis, surgical treatment should be used to avoid further worsening of the proptosis.
Surgical treatment usually involves subtotal thyroidectomy to treat hyperthyroidism, which provides rapid relief of hyperthyroidism and is particularly suitable for patients with markedly enlarged thyroid glands with proptosis and hyperthyroidism with nodules, but has the disadvantage of being invasive and may cause surgical complications such as damage to the recurrent laryngeal nerve and hypoparathyroidism in some cases. Some patients still have recurrence of hyperthyroidism or hypothyroidism after surgery.
What are the pros and cons of hypothyroidism treatment?
Once hypothyroidism is diagnosed, the treatment is relatively simple. Thyroid hormone replacement therapy is used to bring the patient’s thyroid hormone level to normal. However, if heart disease is accompanied by low thyroid hormone, supplemental treatment from small doses is required.
Under what circumstances is radionuclide therapy suitable for bone metastases?
As we all know, patients with malignant tumors will have multiple metastases in various parts of the body when they reach advanced stage, among which bone is also a common metastatic site. Especially for patients with lung cancer, breast cancer and prostate cancer, about 70%~80% of them will have bone metastasis, and nearly half of them have severe bone pain. Usually we apply external irradiation for treatment (radiotherapy), but when multiple bone metastases occur throughout the body, this method is quite limited. If a nuclide bone scan suggests radioactive concentration at the site of multiple bone metastases throughout the body, we can consider applying radionuclide for treatment at this time. Radionuclide internal irradiation for the treatment of bone metastatic cancer can relieve pain, reduce symptoms, improve patients’ survival quality, and even prolong life.
Which patients with bone metastases are suitable for treatment with radionuclide irradiation?
For patients with extensive bone metastases, if the bone imaging shows radioactive concentration at the lesion site, white blood cells above 3.5×109/L and platelets above 90×109/L, they can be treated with radionuclide irradiation.
Why can radionuclide be used to treat bone metastases?
Bone tissue is damaged by the invasion of tumor cells at the site of bone metastasis, and the repairing effect of osteoblasts is extremely active. The radiopharmaceuticals used to treat bone metastases have osteotropic effect, therefore, the metabolically active parts of bone tissue will concentrate the radiopharmaceuticals, while normal bone will concentrate less. In this way, the radiopharmaceuticals will concentrate around the tumor lesion and irradiate the tumor with beta rays emitted by radionuclides to achieve pain relief and destruction of tumor tissue.
Why can 89Sr be applied to treat bone metastasis cancer?
89Sr is a highly osteophilic radionuclide, which is of the same family as calcium and participates in the metabolic process of bone minerals like calcium after entering the body. After intravenous injection, the amount of 89Sr in bone metastasis lesions is 2~25 times of normal bone, and it stays in the cancer lesions, its retention time in bone tumor lesions is about 100 days, emitting rays to kill cancer cells, shrink the lesions and play a good analgesic effect. The distance of the radiation in the tissue is only 2.4mm, which will not damage the surrounding normal tissues or organs.
Is 89Sr safe to treat bone metastases?
There may be transient bone marrow suppression when 89Sr is applied to treat bone metastases. About 20%-30% of patients may have a decrease in white blood cells and platelets after treatment, and most of them can return to the pre-treatment level after 2~3 months. Therefore, the application of 89Sr is safe for the treatment of bone metastasis cancer.
Compared with other treatment methods, what are the advantages of applying radionuclide to treat bone metastatic cancer and is it expensive?
Current methods of treating bone pain caused by bone metastatic cancer such as analgesics, chemotherapy and hormone therapy all have great side effects and the effect is not ideal for advanced patients. Although the application of external irradiation therapy can effectively treat bone pain, it is more effective in treating single bone metastases and is not applicable to extensive bone metastases. Internal radionuclide irradiation therapy is a kind of targeted treatment, which is simple, can be directly injected intravenously, with little damage to the surrounding tissues and few side effects, not only has good pain relief effect, but also has the effect of eliminating and shrinking bone metastases. The commonly used nuclear agents for internal irradiation therapy are 89Sr and 153Sm.
153Sm is a phosphate compound as a carrier to concentrate in the lesion bone site, the highest uptake ratio at the lesion site 3 days after injection, thus the time of pain relief is relatively fast, but the maintenance time of pain relief is relatively short, and monthly injection is needed. The price of each treatment is about 2000 RMB. For 89Sr treatment, the accumulation of drug at the tumor site reaches a peak about 10 days after injection, so the time of pain relief is relatively slow, but the maintenance time is long, the average maintenance time is 3~6 months, so the second treatment time should be at least 3 months apart. The efficiency of 89Sr and 153Sm in the treatment of bone metastases is 80%-90%, especially for patients whose primary tumors are prostate cancer, breast cancer and lung cancer. Moreover, 89Sr has less inhibitory effect on bone marrow than 153Sm. Therefore, 153Sm is recommended for patients with severe disease who want to relieve pain faster and whose families are in relative financial difficulties, while 89Sr is recommended for patients with mild pain who want to maintain pain relief for a longer period of time.
Why is nuclear medicine imaging a functional metabolic and molecular diagnostic imaging technique?
Nuclear medicine imaging is a diagnostic imaging technique at the functional metabolic and cellular molecular level. Patients receive intravenous or oral doses of tiny amounts of imaging drugs called disease “probes”, which are involved in the circulation and metabolism of organs and tissues in the body, and constantly emit extremely weak signals, which are tracked and probed by doctors outside the body using high-tech methods, in the form of numbers, images, curves or photographs. It is also useful for early detection and judgment of abnormal changes in functional metabolism and cellular molecular level in human body, for early localization, characterization, quantification and regular diagnosis of complex and difficult diseases that cannot be detected or difficult to diagnose by conventional radiological imaging, such as various malignant tumors, for correct guidance of reasonable individualized and comprehensive treatment of malignant tumors, and for early screening of malignant tumors, cardiovascular and cerebrovascular diseases and functional brain diseases in high-risk groups. It is very helpful. Nuclear medicine functional imaging is simple, sensitive, specific, non-invasive, safe, easy to repeat, accurate and reliable.
What are the main methods of molecular imaging in nuclear medicine?
Nuclear medicine molecular imaging technology mainly includes PET (Positron Emission Computed Tomography) and SPECT (Single Photon Emission Computed Tomography), which occupy a very important position in molecular imaging research and can make quantitative analysis of physiological and biochemical processes in living tissues, such as blood flow, energy metabolism, protein synthesis, fatty acid metabolism, neurotransmitter synthesis rate It is also possible to quantify physiological and biochemical processes in living tissues, such as blood flow, energy metabolism, protein synthesis, fatty acid metabolism, rate of neurotransmitter synthesis, receptor density, selectivity and kinetics of ligand binding, protein function and gene expression. By directly labeling drugs with positron emitters, we can make prospective judgments on drug dose, site of action, possible toxic side effects, etc., determine the type of metabolic reactions and products, observe the interaction between drugs and other drugs, drug-nutrient interactions, drug-receptor interactions, drug-enzyme interactions, etc., so as to achieve diagnosis and efficacy judgment.
What is SPECT technology?
It is actually a gamma camera with one or more probes rotating 360° around a patient’s organ, acquiring a frame at certain angles during the rotation, and then superimposing the images and reconstructing them into cross-sectional, coronal, sagittal or any desired tomogram in different directions, in section. SPECT can perform both planar and dynamic (functional) imaging of organs.