All chemical elements form isotopes with unstable nuclei, which emit α-particles, β-particles or γ-rays during their half-life. Iodine has 37 types of nuclei with the same charge, but differing in the number of neutrons that determine the mass of the nucleus and the atom. The charge of all isotopes of iodine (I) is 53. When they mean an isotope with a certain number of neutrons, write this number next to the symbol, through a dash. In medical practice, I-124, I-131, I-123 are used. The normal isotope of iodine (not radioactive) is I-127.

The number of neutrons serves as an indicator for various diagnostic and therapeutic procedures. Radioiodine therapy is based on the varying half-lives of the radioactive isotopes of iodine. For example, an element with 123 neutrons decays in 13 hours, with 124 - in 4 days, and I-131 will have a radioactive effect after 8 days. More often, I-131 is used, during the decay of which γ-rays, inert xenon and β-particles are formed.

The effect of radioactive iodine in the treatment

Iodine therapy is prescribed after the removal of the thyroid gland completely. With partial removal or conservative treatment, this method does not make sense to use. The follicles of the thyroid gland receive iodides from the tissue fluid that surrounds them. Iodides enter the tissue fluid by diffusion or by active transport from the blood. During iodine starvation, secretory cells begin to actively capture radioactive iodine, and degenerate cancer cells do this much more intensively.

β-particles, released during half-life, kill cancer cells.

The striking ability of β-particles acts at a distance of 600 - 2000 nm, which is quite enough to destroy only the cellular elements of malignant cells, and not neighboring tissues.

The main goal of radioiodine therapy is the final removal of all remnants of the thyroid gland, because even the most skillful operation leaves behind these remnants. Moreover, in the practice of surgeons, it has already become customary to leave several gland cells around the parathyroid glands for their normal operation, as well as around the recurrent nerve that innervates the vocal cords. The destruction of the iodine isotope occurs not only in the residual tissues of the thyroid gland, but also metastasis in cancerous tumors, which makes it easier to monitor the concentration of thyroglobulin.

γ-rays do not have a therapeutic effect, but they are successfully used in the diagnosis of diseases. The γ-camera built into the scanner helps to determine the localization of radioactive iodine, which serves as a signal for the recognition of cancerous metastases. The accumulation of the isotope occurs on the surface of the front of the neck (in the place of the former thyroid gland), in the salivary glands, along the entire length of the digestive system, in the bladder. Few, but still there are iodine uptake receptors in the mammary glands. Scanning reveals metastases in trimmed and nearby organs. Most often they are found in the cervical lymph nodes, bones, lungs and tissues of the mediastinum.

Treatment prescriptions for radioactive isotopes

Radioiodine therapy is indicated for use in two cases:

If the state of a hypertrophied gland is detected in the form of a toxic goiter (nodular or diffuse). The state of diffuse goiter is characterized by the production of thyroid hormones by the entire secretory tissue of the gland. In nodular goiter, only the nodular tissue secretes hormones. The tasks of introducing radioactive iodine are reduced to the inhibition of the functionality of hypertrophied areas, since the radiation of β-particles destroys precisely those places that are prone to thyrotoxicosis. At the end of the procedure, either the normal function of the gland is restored, or hypothyroidism develops, which is easily normalized when using an analogue of the hormone thyroxine - T4 (L-form).
If a malignant neoplasm of the thyroid gland (papillary or follicular cancer) is found, the surgeon determines the degree of risk. In accordance with this, risk groups are distinguished according to the level of tumor progress and possible distant localization of metastases, as well as the need for radioactive iodine treatment.
The low-risk group includes patients with a small tumor, not exceeding 2 cm and located in the outline of the thyroid gland. No metastases were found in neighboring organs and tissues (especially in the lymph nodes). Such patients do not need to inject radioactive iodine.
Patients with an average risk have a tumor larger than 2 cm, but not exceeding 3 cm. If an unfavorable prognosis develops and the capsule in the thyroid gland germinates, a dose of radioactive iodine of 30-100 mCi is prescribed.
The high-risk group has a pronounced aggressive pattern of cancer growth. There is germination in neighboring tissues and organs, lymph nodes, there may be distant metastases. Such patients require treatment with a radioactive isotope greater than 100 millicuries.

Radioiodine Administration Procedure

The radioactive isotope of iodine (I-131) is synthesized artificially. It is taken in the form of gelatin capsules (liquid) orally. Capsules or liquid are odorless and tasteless, swallowed only with a glass of water. After taking the liquid, it is recommended to immediately rinse your mouth with water and swallow it without spitting it out.

In the presence of dentures, it is better to remove them for a while before using liquid iodine.

You can’t eat for two hours, you can (even need) to take a plentiful drink of water or juice. Iodine-131, not absorbed by the thyroid follicles, is excreted in the urine, so urination should occur every hour with the control of the content of the isotope in the urine. Medicines for the thyroid gland are taken no earlier than 2 days later. It is better if the patient's contacts with other people at this time are strictly limited.

Before the procedure, the doctor must analyze the medications taken and stop them at different times: some of them - a week, others at least 4 days before the procedure. If a woman is of childbearing age, then pregnancy planning will have to be postponed for a period determined by the doctor. Previous surgery requires a test for the presence or absence of tissue capable of absorbing iodine-131. 14 days before the start of the introduction of radioactive iodine, a special diet is prescribed, in which the normal isotope of iodine-127 must be completely eliminated from the body. The list of products for the effective removal of iodine will be prompted by the attending physician.

Treatment of cancerous tumors with radioactive iodine

If the iodine-free diet is correctly observed and the period of restrictions on the intake of hormonal drugs is observed, the thyroid cells are completely cleared of iodine residues. With the introduction of radioactive iodine against the background of iodine starvation, cells tend to capture any isotope of iodine and are affected by β-particles. The more actively cells absorb a radioactive isotope, the more they are affected by it. The dose of irradiation of thyroid follicles that capture iodine is several tens of times greater than the effect of a radioactive element on surrounding tissues and organs.

French experts have calculated that almost 90% of patients with lung metastases survived after treatment with a radioactive isotope. Survival within ten years after the application of the procedure was more than 90%. And these are patients with the last (IVc) stage of a terrible disease.

Of course, the described procedure is not a panacea, because complications after its use are not excluded.

First of all, it is sialadenitis (inflammation of the salivary glands), accompanied by swelling, soreness. This disease develops in response to the introduction of iodine and the absence of thyroid cells capable of capturing it. Then the salivary gland has to take over this function. It should be noted that sialadenitis progresses only at high radiation doses (above 80 mCi).

There are cases of violation of the reproductive function of the reproductive system, but with repeated exposures, the total dose of which exceeds 500 mCi.

Treatment after thyroidectomy

After taking the drug, the patient is placed in a single room, which is equipped in accordance with the specifics.

Medical personnel are limited to contact for up to five days. At this time, visitors should not be allowed into the ward, especially pregnant women and children, in order to protect them from the flow of radiation particles. Urine and saliva of the patient are considered radioactive and are subject to special disposal.

Pros and cons of radioactive iodine treatment

The described procedure cannot be called completely “harmless”. Thus, during the action of a radioactive isotope, temporary phenomena are noted in the form of painful sensations in the region of the salivary glands, tongue, and front of the neck. The mouth is dry, itchy in the throat. The patient is sick, there is frequent urge to vomit, swelling, food becomes not tasty. In addition, old chronic diseases become aggravated, the patient becomes lethargic, gets tired quickly, and is prone to depression.

Despite the negative aspects of treatment, the use of radioactive iodine is increasingly used in the treatment of thyroid gland in clinics.

The positive reasons for this pattern are:

there is no surgical intervention with cosmetic consequences;
general anesthesia is not required;
the relative cheapness of European clinics compared to operations with a high quality of service and scanning equipment.

Danger of radiation on contact

It should be remembered that the benefit provided in the process of using radiation is obvious to the patient himself. For the people around him, radiation can play a cruel joke. Not to mention the visitors of the patient, let us mention that medical workers provide care only when necessary and, of course, in protective clothing and gloves.

After discharge, you should not be in contact with a person closer than 1 meter, and with a long conversation, you should move 2 meters away. In the same bed, even after discharge, it is not recommended to sleep in the same bed with another person for 3 days. Sexual contacts and being near a pregnant woman are strictly prohibited within a week from the date of discharge, which occurs five days after the procedure.

How to behave after irradiation with an isotope of iodine?

Eight days after discharge, children should be kept away from themselves, especially contact. After using the bathroom or toilet, flush three times with water. Hands are washed thoroughly with soap.

It is better for men to sit on the toilet when urinating to prevent splashing of radiation urine. Breastfeeding should be discontinued if the patient is a nursing mother. The clothes in which the patient was on treatment are placed in a bag and washed separately a month or two after discharge. Personal belongings are removed from common areas and storage. In case of emergency admission to the hospital, it is necessary to warn the medical staff about the recent course of iodine-131 irradiation.

Iodine isotope I-131 has long been successfully used in the diagnosis and treatment of thyroid diseases. But for some reason, not only among patients in our country, but also among medical workers, there are different prejudices and fears about the method of radioiodine therapy. This is due to the rare use of this treatment method in clinical practice and the lack of awareness of doctors in this matter.

What is hidden under the terrible name "radioactive iodine"

Radioactive iodine (I-131)- this is one of the isotopes of the most common iodine (I-126). An isotope is a variety of an atom of a chemical element that has the same serial number but differs in its mass number. This difference makes the atom of the isotope unstable, which leads to its decay with radioactive radiation. In nature, there are many isotopes of the same chemical element, and iodine is no exception.

Two isotopes of radioactive iodine have been used in medicine- I-131 and I-123. Iodine with a mass number of 123 has no cytotoxic effect on thyroid cells and is used only for diagnostic purposes (thyroid scan).

I-131 has the ability to spontaneously disintegrate an atom. The half-life is 8 days. In this case, a neutral xenon atom, a gamma-ray quantum and a beta particle (electron) are formed. The therapeutic effect is carried out precisely thanks to the beta particles. Such particles have a very high speed of movement, but a small range in tissues (up to 2 mm). Thus, they penetrate into biological tissues (thyroid cells) and destroy the cell (cytotoxic effect).

Thanks to iodine accumulates in the human body exclusively in the cells of the thyroid gland, I-131 performs its action only here, it does not act on any other tissues.

Gamma radiation, which is formed during the radioactive decay of an iodine atom, penetrates the human body (has a long range, but little energy). Thus, it does not affect the cells of the body. But it can be used for diagnostic purposes. So you can determine where else in the body iodine has accumulated using a special gamma camera that records such radiation. If there are such foci, then we can think about the existence of metastases of thyroid cancer.

Radioactive iodine therapy is prescribed in 2 cases:

with hyperproduction of thyroid hormones (diffuse toxic goiter, thyrotoxicosis, thyroid adenoma);
malignant tumor of the thyroid gland (papillary and follicular cancer).

Therapy with radioactive iodine refers to highly effective and highly selective (influence only on thyroid cells) methods of treatment of thyroid diseases. It has long been actively used in the US and Europe. There is no need to be afraid of such treatment, because it can give you a healthy and long life.

All chemical elements form isotopes with unstable nuclei, which emit α-particles, β-particles or γ-rays during their half-life. Iodine has 37 types of nuclei with the same charge, but differing in the number of neutrons that determine the mass of the nucleus and the atom. The charge of all isotopes of iodine (I) is 53. When they mean an isotope with a certain number of neutrons, write this number next to the symbol, through a dash. In medical practice, I-124, I-131, I-123 are used. The normal isotope of iodine (not radioactive) is I-127.

The effect of radioactive iodine in the treatment

β-particles, released during half-life, kill cancer cells. The striking ability of β-particles acts at a distance of 600 - 2000 nm, which is quite enough to destroy only the cellular elements of malignant cells, and not neighboring tissues.

Treatment prescriptions for radioactive isotopes

Radioiodine therapy is indicated for use in two cases:

If the state of a hypertrophied gland is detected in the form of a toxic goiter (nodular or diffuse). The state of diffuse goiter is characterized by the production of thyroid hormones by the entire secretory tissue of the gland. In nodular goiter, only the nodular tissue secretes hormones. The tasks of introducing radioactive iodine are reduced to the inhibition of the functionality of hypertrophied areas, since the radiation of β-particles destroys precisely those places that are prone to thyrotoxicosis. At the end of the procedure, either the normal function of the gland is restored, or hypothyroidism develops, which is easily normalized when using an analogue of the hormone thyroxine - T4 (L-form). If a malignant neoplasm of the thyroid gland (papillary or follicular cancer) is found, the surgeon determines the degree of risk. In accordance with this, risk groups are distinguished according to the level of tumor progress and possible distant localization of metastases, as well as the need for radioactive iodine treatment. The low-risk group includes patients with a small tumor, not exceeding 2 cm and located in the outline of the thyroid gland. No metastases were found in neighboring organs and tissues (especially in the lymph nodes). Such patients do not need to inject radioactive iodine. Patients with an average risk have a tumor larger than 2 cm, but not exceeding 3 cm. If an unfavorable prognosis develops and the capsule in the thyroid gland germinates, a dose of radioactive iodine of 30-100 mCi is prescribed. The high-risk group has a pronounced aggressive pattern of cancer growth. There is germination in neighboring tissues and organs, lymph nodes, there may be distant metastases. Such patients require treatment with a radioactive isotope greater than 100 millicuries.

Radioiodine Administration Procedure

In the presence of dentures, it is better to remove them for a while before using liquid iodine.

Treatment of cancerous tumors with radioactive iodine

Whole body being scanned after sequential radioactive iodine therapy in a patient with papillary thyroid cancer

Of course, the described procedure is not a panacea, because complications after its use are not excluded. First of all, it is sialadenitis (inflammation of the salivary glands), accompanied by swelling, soreness. This disease develops in response to the introduction of iodine and the absence of thyroid cells capable of capturing it. Then the salivary gland has to take over this function. It should be noted that sialadenitis progresses only at high radiation doses (above 80 mCi).

There are cases of violation of the reproductive function of the reproductive system, but with repeated exposures, the total dose of which exceeds 500 mCi.

Often, cancer patients are prescribed iodine therapy after removal of the thyroid gland. The objective of this procedure is the final defeat of cancer cells remaining after the operation, not only in the thyroid gland, but also in the blood. After taking the drug, the patient is placed in a single room, which is equipped in accordance with the specifics.

Medical personnel are limited to contact for up to five days. At this time, visitors should not be allowed into the ward, especially pregnant women and children, in order to protect them from the flow of radiation particles. Urine and saliva of the patient are considered radioactive and are subject to special disposal.

Pros and cons of radioactive iodine treatment

Despite the negative aspects of treatment, the use of radioactive iodine is increasingly used in the treatment of thyroid gland in clinics. The positive reasons for this pattern are:

there is no surgical intervention with cosmetic consequences; general anesthesia is not required; the relative cheapness of European clinics compared to operations with a high quality of service and scanning equipment.

Danger of radiation on contact

How to behave after irradiation with an isotope of iodine?

Eight days after discharge, children should be kept away from themselves, especially contact. After using the bathroom or toilet, flush three times with water. Hands are washed thoroughly with soap. It is better for men to sit on the toilet when urinating to prevent splashing of radiation urine. Breastfeeding should be discontinued if the patient is a nursing mother. The clothes in which the patient was on treatment are placed in a bag and washed separately a month or two after discharge. Personal belongings are removed from common areas and storage. In case of emergency admission to the hospital, it is necessary to warn the medical staff about the recent course of iodine-131 irradiation.

Treatment with radioactive iodine is sometimes the only chance of saving a person suffering from one of the forms (papillary or follicular) of differentiated thyroid cancer.

The main goal of radioiodine therapy is the destruction of thyroid follicular cells. However, not every patient can get a referral for this type of treatment, which has a number of indications and contraindications.

What is radioiodine therapy, in what cases is it used, how to prepare for it, and in which clinics can one receive treatment? All these questions can be answered in our article.

The concept of the method

In radioiodine therapy, radioactive iodine is used (in the medical literature it can be referred to as iodine-131, radioiodine, I-131) - one of the thirty-seven isotopes we all know of iodine-126, which is available in almost every first-aid kit.

With a half-life of eight days, radioiodine breaks down spontaneously in the patient's body. In this case, the formation of xenon and two types of radioactive radiation: beta and gamma radiation.

The therapeutic effect of radioiodine therapy is provided by the flow of beta particles (fast electrons), which have an increased penetrating ability into biological tissues located around the iodine-131 accumulation zone due to the high escape velocity. The penetration depth of beta particles is 0.5-2 mm. Since their range is limited to these values only, radioactive iodine works exclusively within the thyroid gland.

The equally high penetrating power of gamma particles allows them to easily pass through any tissue of the patient's body. For their registration, high-tech equipment is used - gamma cameras. Not producing any therapeutic effect, gamma radiation helps to detect the localization of radioiodine accumulations.

Having scanned the patient's body in a gamma camera, the specialist can easily identify the foci of accumulation of a radioactive isotope.

This information is of great importance for the treatment of patients suffering from thyroid cancer, since the luminous foci that appear in their bodies after a course of radioiodine therapy allow us to draw a conclusion about the presence and location of malignant neoplasm metastases.

The main goal of radioactive iodine treatment is the complete destruction of the tissues of the affected thyroid gland.

The therapeutic effect, which occurs two to three months after the start of therapy, is akin to the result obtained during the surgical removal of this organ. Some patients with a recurrence of pathology may be assigned a second course of radioiodine therapy.

Indications and contraindications

Radioiodine therapy is prescribed for the treatment of patients suffering from:

Hyperthyroidism is a disease caused by an increased activity of the functioning of the thyroid gland, accompanied by the appearance of small benign nodular neoplasms. Thyrotoxicosis - a condition caused by an excess of thyroid hormones, which is a complication of the aforementioned disease. All types of thyroid cancer, characterized by the occurrence of malignant neoplasms in the tissues of the affected organ and accompanied by the addition of an inflammatory process. Treatment with radioactive iodine is especially necessary for patients in whose bodies distant metastases have been found that have the ability to selectively accumulate this isotope. The course of radioiodine therapy in relation to such patients is carried out only after a surgical operation to remove the affected gland. With the timely use of radioiodine therapy, most patients suffering from thyroid cancer can be completely cured.

Radioiodine therapy has proven effective in the treatment of Graves' disease, as well as nodular toxic goiter (otherwise referred to as functional autonomy of the thyroid gland). In these cases, radioactive iodine treatment is used instead of surgery.

The use of radioiodine therapy is especially justified in case of recurrence of the pathology of the already operated thyroid gland. Most often, such relapses occur after operations to remove diffuse toxic goiter.

Given the high likelihood of postoperative complications, experts prefer to use radioiodine treatment tactics.

An absolute contraindication to the appointment of radioid therapy is:

Pregnancy: exposure to radioactive iodine on the fetus can provoke malformations of its further development. Infant breastfeeding period. Breastfeeding mothers taking radioactive iodine treatment need to wean the baby for quite a long time.

Pros and cons of the procedure

The use of iodine-131 (compared to surgical removal of the affected thyroid gland) has a number of advantages:

It is not associated with the need to introduce the patient into a state of anesthesia. Radiotherapy does not require a rehabilitation period. After treatment with an isotope, the patient's body remains unchanged: no scars and scars (inevitable after surgery) that disfigure the neck remain on it. Swelling of the larynx and unpleasant sore throat, which develop in a patient after taking a capsule with radioactive iodine, are easily stopped with the help of topical preparations. Radioactive radiation associated with the intake of an isotope is localized mainly in the tissues of the thyroid gland - it almost does not spread to other organs. Since reoperation for a malignant tumor of the thyroid gland can be life threatening, radioiodine therapy, which can completely stop the consequences of recurrence, is a completely safe alternative to surgery.

At the same time, radioiodine therapy has an impressive list of negative aspects:

It should not be used on pregnant women. Nursing mothers are forced to stop breastfeeding their children. Given the ability of the ovaries to accumulate a radioactive isotope, it will be necessary to protect against pregnancy for six months after completion of therapy. Due to the high probability of violations associated with the normal production of hormones necessary for the proper development of the fetus, offspring should be planned only two years after the use of iodine-131. Hypothyroidism, which inevitably develops in patients undergoing radioiodine therapy, will require long-term treatment with hormonal drugs. After the use of radioiodine, there is a high probability of developing autoimmune ophthalmopathy, leading to a change in all soft tissues of the eye (including nerves, fatty tissue, muscles, synovial membranes, fatty and connective tissues). A small amount of radioactive iodine accumulates in the tissues of the mammary glands, ovaries and prostate. Exposure to iodine-131 can provoke a narrowing of the lacrimal and salivary glands with a subsequent change in their functioning. Radioiodine therapy can lead to significant weight gain, fibromyalgia (severe muscle pain) and causeless fatigue. Against the background of radioactive iodine treatment, an exacerbation of chronic diseases can occur: gastritis, cystitis and pyelonephritis, patients often complain of changes in taste, nausea and vomiting. All of these conditions are short-lived and respond well to symptomatic treatment. The use of radioactive iodine increases the likelihood of developing a malignant tumor of the small intestine and thyroid gland. One of the main arguments of opponents of radioidtherapy is the fact that the thyroid gland, destroyed as a result of exposure to the isotope, will be lost forever. As a counterargument, one can argue that after the surgical removal of this organ, its tissues cannot be restored either. Another negative factor of radioiodine therapy is associated with the need for a three-day strict isolation of patients who have taken a capsule with iodine-131. Since their body then begins to emit two types (beta and gamma) of radioactive radiation, during this period, patients become dangerous to others. All clothing and items used by a patient undergoing radioiodine treatment are subject to either special treatment or disposal in compliance with radioactive protection measures.

Which is better, surgery or radioactive iodine?

Opinions on this subject are contradictory even among specialists involved in the treatment of thyroid diseases.

Some of them believe that after a thyroidectomy (a surgical operation to remove the thyroid gland), a patient taking estrogen-containing drugs can lead a completely normal life, since a regular intake of thyroxine can replenish the function of the missing gland without causing side effects. Proponents of radioiodine therapy emphasize that this type of treatment completely eliminates the side effects (the need for anesthesia, removal of the parathyroid glands, damage to the recurrent laryngeal nerve) that are inevitable during a surgical operation. Some of them are even cunning, claiming that radioiodine therapy will lead to euthyroidism (normal functioning of the thyroid gland). This is an extremely erroneous assertion. In fact, radioiodine therapy (as well as thyroidectomy surgery) is aimed at achieving hypothyroidism - a condition characterized by complete suppression of the thyroid gland. In this sense, both methods of treatment pursue completely identical goals. The main advantages of radioiodine treatment are complete painlessness and non-invasiveness, as well as the absence of the risk of complications arising after surgery. Complications associated with exposure to radioactive iodine, in patients, as a rule, are not observed.

So what is the best technique? In each case, the last word remains with the attending physician. In the absence of contraindications to the appointment of radioiodine therapy in a patient (suffering, for example, Graves' disease), he will most likely advise to prefer it. If the doctor believes that it is more expedient to perform a thyroidectomy, you must listen to his opinion.

Training

It is necessary to start preparation for taking the isotope two weeks before the start of treatment.

It is advisable not to allow iodine to get on the surface of the skin: patients are prohibited from lubricating wounds with iodine and applying an iodine mesh to the skin. Patients should refuse to visit the salt room, bathing in sea water and inhaling sea air saturated with iodine. Residents of the sea coasts need isolation from the external environment at least four days before the start of therapy. Vitamin complexes, nutritional supplements and drugs containing iodine and hormones fall under a strict ban: they should be discontinued four weeks before radioiodine therapy. A week before taking radioactive iodine, all drugs prescribed for the treatment of hyperthyroidism are canceled. Women of childbearing age are required to take a pregnancy test: this is necessary to eliminate the risk of pregnancy. Before the procedure for taking a capsule with radioactive iodine, a test is carried out for the absorption of radioactive iodine by the tissues of the thyroid gland. If the gland was removed surgically, an iodine sensitivity test of the lungs and lymph nodes is performed, since it is they who take on the function of accumulating iodine in such patients.

Diet before therapy

The first step in preparing a patient for radioiodine therapy is to follow a low-iodine diet aimed at reducing the iodine content in the patient's body in every possible way so that the effect of the radioactive drug will bring a more tangible effect.

Because the low-iodine diet is given two weeks prior to taking the radioactive iodine capsule, the patient is brought to a state of iodine starvation; as a result, tissues capable of absorbing iodine do so with maximum activity.

Prescribing a diet low in iodine requires an individual approach to each patient, so the recommendations of the attending physician in each case are of decisive importance.

A low-iodine diet does not mean that the patient should give up salt. You should only use a non-iodized product and limit its amount to eight grams per day. The diet is called low iodine because foods low in iodine (less than 5 micrograms per serving) are still allowed.

Patients undergoing radioiodine therapy should completely abstain from:

Seafood (shrimp, crab sticks, sea fish, mussels, crabs, algae, sea kale and dietary supplements based on them). All types of dairy products (sour cream, butter, cheeses, yoghurts, dry milk porridges). Ice cream and milk chocolate (a small amount of dark chocolate and cocoa powder is allowed to be included in the patient's diet). Salted nuts, instant coffee, chips, canned meat and fruit, french fries, oriental dishes, ketchup, salami, pizza. Dried apricots, bananas, cherries, applesauce. Iodized eggs and foods with a lot of egg yolks. This does not apply to the use of egg whites that do not contain iodine: during the diet, you can eat them without any restrictions. Dishes and products colored in different shades of brown, red and orange, as well as medicines containing food dyes of similar colors, since many of them may contain iodine-containing dye E127. Bakery products of factory production containing iodine; corn flakes. Soy products (tofu cheese, sauces, soy milk) rich in iodine. Greens of parsley and dill, leaf and watercress. Cauliflower, zucchini, persimmons, green peppers, olives, potatoes, baked in a "uniform".

During the period of a low-one diet, the use of:

Peanut butter, unsalted peanuts, coconuts. Sugar, honey, fruit and berry jams, jellies and syrups. Fresh apples, grapefruits and other citrus fruits, pineapples, cantaloupe, raisins, peaches (and their juices). White and brown rice. Egg noodles. Vegetable oils (except soy). Raw and freshly cooked vegetables (except for potatoes, beans, and soybeans). Frozen vegetables. Poultry meat (chicken, turkey). Beef, veal, lamb meat. Dried herbs, black pepper. Cereal dishes, pasta (in limited quantities). Carbonated soft drinks (lemonade, erythrosin-free diet cola), tea, and well-filtered coffee.

Treatment with radioactive iodine of the thyroid gland

This type of treatment is one of the highly effective procedures, the distinguishing feature of which is the use of a small amount of a radioactive substance that selectively accumulates precisely in those areas that require therapeutic exposure.

It has been proven that, compared with remote beam irradiation (with a comparable dosage of exposure), radioiodine therapy is able to create a dose of radiation in the tissues of the tumor focus fifty times higher than that of radiation treatment, while the effect on bone marrow cells and the structures of bones and muscles was tens of times smaller.

The selective accumulation of the radioactive isotope and the shallow penetration of beta-particles into the thickness of biological structures provides the possibility of a point effect on the tissues of tumor foci with their subsequent destruction and complete safety in relation to adjacent organs and tissues.

How is radioiodine therapy performed? During the session, the patient receives a gelatin capsule of the usual size (devoid of smell and taste), inside which is radioactive iodine. The capsule should be swallowed quickly with a large (at least 400 ml) amount of water.

Sometimes the patient is offered radioactive iodine in liquid form (usually in a test tube). After taking such a drug, the patient will have to rinse his mouth thoroughly, then swallowing the water used for this. Patients with removable dentures will be asked to remove them before the procedure.

In order for radioiodine to be better absorbed, providing a high therapeutic effect, the patient should refrain from eating and drinking any drinks for an hour.

After taking the capsule, radioactive iodine begins to accumulate in the tissues of the thyroid gland. If it was removed surgically, the accumulation of the isotope occurs either in the tissues remaining from it, or in partially altered organs.

Excretion of radioiodine occurs through feces, urine, secretion of sweat and salivary glands, the patient's breath. That is why the radiation will settle on the objects of the environment surrounding the patient. All patients are warned in advance that a limited number of things should be taken to the clinic. Upon admission to the clinic, they are required to change into the hospital linen and clothes issued to them.

After receiving radioiodine, patients in an isolated box must strictly observe the following rules:

When brushing your teeth, avoid splashing water. The toothbrush should be thoroughly rinsed with water. When visiting the toilet, use the toilet carefully, avoiding splashing of urine (for this reason, men should only urinate while sitting). It is necessary to flush urine and stool at least twice, waiting for the tank to fill. Any accidental spillage of fluid or secretions should be reported to the nurse or nurse. During vomiting, the patient should use a plastic bag or toilet (flush the vomit twice), but in no case - not a sink. It is forbidden to use reusable handkerchiefs (there must be a supply of paper ones). Used toilet paper is flushed out with stools. The front door must be kept closed. Leftover food is placed in a plastic bag. Feeding birds and small animals through the window is strictly prohibited. Showering should be daily. In the absence of a chair (it should be daily), you need to inform the nurse: the attending physician will definitely prescribe a laxative.

Visitors (especially small children and pregnant women) are not allowed near a patient in strict isolation. This is done in order to prevent their radiation contamination by the flow of beta and gamma particles.

Treatment after thyroidectomy

Radioiodine therapy is often given to cancer patients who have undergone thyroidectomy. The main goal of such treatment is the complete destruction of abnormal cells that could remain not only in the location of the removed organ, but also in the blood plasma.

The patient who has taken the drug is sent to an isolated ward, equipped with the specifics of treatment. All contacts of the patient with medical personnel dressed in a special protective suit are limited to the most necessary procedures.

Patients treated with radioactive iodine must:

Increase the amount of fluid you drink to speed up the elimination of iodine-131 decay products from the body. Shower as often as possible. Use personal hygiene items. Using the toilet, pull off the water twice. Change underwear and bedding daily. Since radiation is perfectly removed by washing, you can wash the patient's things together with the clothes of the rest of the family. Avoid close contact with small children: pick them up and kiss them. Stay close to babies as little as possible. Within three days after discharge (it is carried out on the fifth day after taking the isotope), sleep only alone, separately from healthy people. It is allowed to have sexual intercourse, as well as to be near a pregnant woman, only one week after discharge from the clinic. If a patient who has recently undergone radioactive iodine treatment is urgently admitted to a hospital, he is obliged to inform the medical staff about this, even if the exposure was carried out in the same clinic. All patients who have undergone radioiodine therapy will take thyroxin for life and visit the endocrinologist's office twice a year. In all other respects, their quality of life will be the same as before treatment. The above restrictions are temporary.

Effects

Radioiodine therapy can cause certain complications:

Sialadenitis - an inflammatory disease of the salivary glands, characterized by an increase in their volume, compaction and soreness. The impetus for the development of the disease is the introduction of a radioactive isotope against the background of the absence of a remote thyroid gland. In a healthy person, thyroid cells would fire up to eliminate the threat and absorb the radiation. In the body of the operated person, this function is taken over by the salivary glands. The progression of sialadenitis occurs only when a high (above 80 millicurie - mCi) radiation dose is received. Various reproductive disorders, but such a reaction of the body occurs only as a result of repeated exposures with a total dosage exceeding 500 mCi.

Everyone knows the high danger of radioactive iodine-131, which caused a lot of trouble after the accidents in Chernobyl and Fukushima-1. Even minimal doses of this radionuclide cause mutations and cell death in the human body, but the thyroid gland suffers especially from it. The beta and gamma particles formed during its decay are concentrated in its tissues, causing severe radiation and the formation of cancerous tumors.

Radioactive iodine: what is it?

Iodine-131 is a radioactive isotope of ordinary iodine, called "radioiodine". Due to a fairly long half-life (8.04 days), it quickly spreads over large areas, causing radiation contamination of soil and vegetation. I-131 radioiodine was first isolated in 1938 by Seaborg and Livinggood by irradiating tellurium with a stream of deuterons and neutrons. Subsequently, Abelson discovered it among the fission products of the atoms of uranium and thorium-232.

Sources of radioiodine

Radioactive iodine-131 is not found in nature and enters the environment from man-made sources:

Nuclear power plants.
Pharmaceutical production.
Tests of atomic weapons.

The technological cycle of any power or industrial nuclear reactor includes the fission of uranium or plutonium atoms, during which a large amount of iodine isotopes accumulate in the plants. Over 90% of the entire family of nuclides are short-lived isotopes of iodine 132-135, the rest is radioactive iodine-131. During the normal operation of a nuclear power plant, the annual release of radionuclides is small due to filtration, which ensures the decay of nuclides, and is estimated by experts at 130-360 Gbq. If there is a violation of the tightness of a nuclear reactor, radioiodine, having high volatility and mobility, immediately enters the atmosphere along with other inert gases. In the gas and aerosol emission, it is mostly contained in the form of various organic substances. Unlike inorganic iodine compounds, organic derivatives of the iodine-131 radionuclide pose the greatest danger to humans, since they easily penetrate the lipid membranes of cell walls into the body and are subsequently carried with blood to all organs and tissues.

Major accidents that have become a source of iodine-131 contamination

In total, there are two major accidents at nuclear power plants that have become sources of radioiodine contamination of large areas - Chernobyl and Fukushima-1. During the Chernobyl disaster, all the iodine-131 accumulated in the nuclear reactor was released into the environment along with the explosion, which led to radiation contamination of a zone with a radius of 30 kilometers. Strong winds and rains carried radiation around the world, but the territories of Ukraine, Belarus, the southwestern regions of Russia, Finland, Germany, Sweden, and the UK were especially affected.

In Japan, explosions at the first, second, third reactors and the fourth power unit of the Fukushima-1 nuclear power plant occurred after a strong earthquake. As a result of the violation of the cooling system, several radiation leaks occurred, leading to a 1250-fold increase in the number of iodine-131 isotopes in sea water at a distance of 30 km from the nuclear power plant.

Another source of radioiodine is nuclear weapons testing. So, in the 50-60s of the twentieth century, explosions of nuclear bombs and shells were carried out in the state of Nevada in the United States. Scientists noticed that I-131 formed as a result of explosions fell out in the nearest areas, and it was practically absent in semi-global and global fallouts due to a short half-life. That is, during the migrations, the radionuclide had time to decompose before falling along with precipitation to the Earth's surface.

Biological effects of iodine-131 on humans

Radioiodine has a high migration ability, easily enters the human body with air, food and water, and also enters through the skin, wounds and burns. At the same time, it is quickly absorbed into the blood: after an hour, 80-90% of the radionuclide is absorbed. Most of it is absorbed by the thyroid gland, which does not distinguish stable iodine from its radioactive isotopes, and the smallest part is absorbed by muscles and bones.

By the end of the day, up to 30% of the total incoming radionuclide is fixed in the thyroid gland, and the accumulation process directly depends on the functioning of the organ. If hypothyroidism is observed, then radioiodine is absorbed more intensively and accumulates in the tissues of the thyroid gland in higher concentrations than with reduced gland function.

Basically, iodine-131 is excreted from the human body with the help of the kidneys within 7 days, only a small part of it is removed along with sweat and hair. It is known that it evaporates through the lungs, but it is still not known how much is excreted from the body in this way.

Iodine-131 toxicity

Iodine-131 is a source of dangerous β- and γ-irradiation in a ratio of 9:1, capable of causing both mild and severe radiation injuries. Moreover, the most dangerous is the radionuclide that enters the body with water and food. If the absorbed dose of radioiodine is 55 MBq/kg of body weight, acute exposure of the whole body occurs. This is due to the large area of beta-irradiation, which causes a pathological process in all organs and tissues. The thyroid gland is especially severely damaged, intensively absorbing radioactive isotopes of iodine-131 together with stable iodine.

The problem of the development of thyroid pathology became relevant during the accident at the Chernobyl nuclear power plant, when the population was exposed to I-131. People received large doses of radiation not only by inhaling contaminated air, but also by drinking fresh cow's milk with a high content of radioiodine. Even the measures taken by the authorities to exclude natural milk from the sale did not solve the problem, since about a third of the population continued to drink milk obtained from their own cows.

It's important to know!
Especially strong irradiation of the thyroid gland occurs when dairy products are contaminated with iodine-131 radionuclide.

As a result of radiation, the function of the thyroid gland decreases, with the subsequent possible development of hypothyroidism. This not only damages the thyroid epithelium, where hormones are synthesized, but also destroys the nerve cells and blood vessels of the thyroid gland. The synthesis of the necessary hormones is sharply reduced, the endocrine status and homeostasis of the whole organism are disturbed, which can serve as the beginning of the development of cancerous tumors of the thyroid gland.

Radioiodine is especially dangerous for children, since their thyroid glands are much smaller than those of an adult. Depending on the age of the child, the weight can be from 1.7 g to 7 g, while in an adult it is about 20 grams. Another feature is that radiation damage to the endocrine gland can be latent for a long time and manifest itself only during intoxication, illness, or during puberty.

A high risk of developing thyroid cancer occurs in children under one year of age who have received a high dose of irradiation with the isotope I-131. Moreover, the high aggressiveness of tumors has been precisely established - within 2-3 months, cancer cells penetrate into the surrounding tissues and blood vessels, metastasize to the lymph nodes of the neck and lungs.

It's important to know!
Thyroid tumors are 2-2.5 times more common in women and children than in men. The latent period of their development, depending on the dose of radioiodine received by a person, can reach 25 years or more, in children this period is much shorter - on average, about 10 years.

"Useful" iodine-131

Radioiodine, as a remedy for toxic goiter and cancerous tumors of the thyroid gland, began to be used as early as 1949. Radiotherapy is considered a relatively safe method of treatment; without it, various organs and tissues are affected in patients, the quality of life worsens and its duration decreases. Today, the I-131 isotope is used as an additional tool to combat the recurrence of these diseases after surgery.

Like stable iodine, radioiodine is accumulated and retained for a long time by thyroid cells, which use it for the synthesis of thyroid hormones. Since tumors continue to perform a hormone-forming function, they accumulate iodine-131 isotopes. When they decay, they form beta particles with a range of 1-2 mm, which locally irradiate and destroy thyroid cells, and the surrounding healthy tissues are practically not exposed to radiation.

The radioactive isotope of iodine 131 has a half-life. Radioactive isotopes produced by fission (Digest)

During fission, various isotopes are formed, one might say, half of the periodic table. The probability of producing isotopes is different. Some isotopes are more likely to be formed, some are much less (see figure). Almost all of them are radioactive. However, most of them have very short half-lives (minutes or less) and rapidly decay into stable isotopes. However, among them there are isotopes that, on the one hand, are readily formed during fission, and on the other hand, have half-lives of days and even years. They are the main danger for us. Activity, i.e. the number of decays per unit time and, accordingly, the number of "radioactive particles", alpha and/or beta and/or gamma, is inversely proportional to the half-life. Thus, if there are the same number of isotopes, the activity of an isotope with a shorter half-life will be higher than with a longer one. But the activity of an isotope with a shorter half-life will fall off faster than one with a longer one. Iodine-131 is formed during fission with approximately the same "hunt" as cesium-137. But iodine-131 has a half-life of "only" 8 days, while cesium-137 has about 30 years. In the process of fission of uranium, at first the number of its fission products, both iodine and cesium, increases, but soon equilibrium comes to iodine - how much it is formed, so much decays. With caesium-137, due to its relatively long half-life, this equilibrium is far from being reached. Now, if there was a release of decay products into the external environment, at the initial moments of these two isotopes, iodine-131 poses the greatest danger. Firstly, due to the peculiarities of fission, a lot of it is formed (see Fig.), and secondly, due to the relatively short half-life, its activity is high. Over time (after 40 days), its activity will drop by 32 times, and soon it will practically not be visible. But cesium-137 at first may not "shine" so much, but its activity will subside much more slowly.
Below are the most "popular" isotopes that pose a danger in case of accidents at nuclear power plants.

radioactive iodine

Among the 20 radioisotopes of iodine formed in the fission reactions of uranium and plutonium, a special place is occupied by 131-135 I (T 1/2 = 8.04 days; 2.3 h; 20.8 h; 52.6 min; 6.61 h), characterized by a high yield in fission reactions, high migratory ability and bioavailability.

In the normal mode of operation of nuclear power plants, releases of radionuclides, including radioisotopes of iodine, are small. Under emergency conditions, as evidenced by major accidents, radioactive iodine, as a source of external and internal exposure, was the main damaging factor in the initial period of the accident.

Simplified scheme for the decay of iodine-131. The decay of iodine-131 produces electrons with energies up to 606 keV and gamma quanta, mainly with energies of 634 and 364 keV.

The main source of radioiodine intake for the population in the zones of radionuclide contamination was local food of plant and animal origin. A person can receive radioiodine along the chains:

plants → human,
plants → animals → human,
water → hydrobionts → human.

Surface contaminated milk, fresh dairy products and leafy vegetables are usually the main source of radioiodine intake for the population. Assimilation of the nuclide by plants from the soil, given the short period of its life, is of no practical importance.

In goats and sheep, the content of radioiodine in milk is several times higher than in cows. Hundredths of incoming radioiodine accumulate in animal meat. Significant amounts of radioiodine accumulate in the eggs of birds. The coefficients of accumulation (excess over the content in water) 131 I in marine fish, algae, mollusks reaches 10, 200-500, 10-70, respectively.

The isotopes 131-135 I are of practical interest. Their toxicity is low compared to other radioisotopes, especially alpha-emitting ones. Acute radiation injuries of severe, moderate and mild degree in an adult can be expected with oral intake of 131 I in the amount of 55, 18 and 5 MBq/kg of body weight. The toxicity of the radionuclide upon inhalation intake is approximately twice as high, which is associated with a larger area of contact beta irradiation.

All organs and systems are involved in the pathological process, especially severe damage in the thyroid gland, where the highest doses are formed. The doses of irradiation of the thyroid gland in children due to its small mass when receiving the same amount of radioiodine are much higher than in adults (the mass of the gland in children, depending on age, is 1: 5-7 g, in adults - 20 g).

Radioactive Iodine Radioactive iodine contains much more detailed information, which, in particular, may be useful to medical professionals.

radioactive cesium

Radioactive cesium is one of the main dose-forming radionuclides of uranium and plutonium fission products. The nuclide is characterized by high migratory ability in the environment, including food chains. The main source of radiocesium intake for humans is food of animal and vegetable origin. Radioactive cesium supplied to animals with contaminated feed accumulates mainly in muscle tissue (up to 80%) and in the skeleton (10%).

After the decay of radioactive isotopes of iodine, radioactive cesium is the main source of external and internal exposure.

In goats and sheep, the content of radioactive cesium in milk is several times higher than in cows. In significant quantities, it accumulates in the eggs of birds. The coefficients of accumulation (excess over the content in water) of 137 Cs in the muscles of fish reaches 1000 or more, in mollusks - 100-700,
crustaceans - 50-1200, aquatic plants - 100-10000.

The intake of cesium to a person depends on the nature of the diet. So after the Chernobyl accident in 1990, the contribution of various products to the average daily intake of radiocesium in the most contaminated areas of Belarus was as follows: milk - 19%, meat - 9%, fish - 0.5%, potatoes - 46%, vegetables - 7.5%, fruits and berries - 5%, bread and bakery products - 13%. An increased content of radiocesium is recorded in residents who consume large quantities of "gifts of nature" (mushrooms, wild berries, and especially game).

Radiocesium, entering the body, is relatively evenly distributed, which leads to almost uniform exposure of organs and tissues. This is facilitated by the high penetrating power of gamma quanta of its daughter nuclide 137m Ba, which is approximately 12 cm.

In the original article by I.Ya. Vasilenko, O.I. Vasilenko. Radioactive cesium contains much more detailed information about radioactive cesium, which, in particular, may be useful to medical professionals.

radioactive strontium

After the radioactive isotopes of iodine and cesium, the next most important element whose radioactive isotopes contribute the most to pollution is strontium. However, the share of strontium in irradiation is much smaller.

Natural strontium belongs to microelements and consists of a mixture of four stable isotopes 84Sr (0.56%), 86Sr (9.96%), 87Sr (7.02%), 88Sr (82.0%). According to the physicochemical properties, it is an analogue of calcium. Strontium is found in all plant and animal organisms. The body of an adult contains about 0.3 g of strontium. Almost all of it is in the skeleton.

Under the conditions of normal operation of nuclear power plants, releases of radionuclides are insignificant. They are mainly due to gaseous radionuclides (radioactive noble gases, 14 C, tritium and iodine). Under conditions of accidents, especially large ones, releases of radionuclides, including strontium radioisotopes, can be significant.

Of greatest practical interest are 89 Sr
(T 1/2 = 50.5 days) and 90 Sr
(T 1/2 = 29.1 years), characterized by a high yield in the fission reactions of uranium and plutonium. Both 89 Sr and 90 Sr are beta emitters. The decay of 89 Sr produces a stable isotope of yttrium ( 89 Y). The decay of 90 Sr produces beta-active 90 Y, which in turn decays to form a stable isotope of zirconium (90 Zr).

C scheme of the decay chain 90 Sr → 90 Y → 90 Zr. The decay of strontium-90 produces electrons with energies up to 546 keV; the subsequent decay of yttrium-90 produces electrons with energies up to 2.28 MeV.

In the initial period, 89 Sr is one of the components of environmental pollution in the zones of near fallout of radionuclides. However, 89 Sr has a relatively short half-life and over time 90 Sr begins to predominate.

Animals receive radioactive strontium mainly with food and, to a lesser extent, with water (about 2%). In addition to the skeleton, the highest concentration of strontium was noted in the liver and kidneys, the minimum - in the muscles and especially in fat, where the concentration is 4-6 times lower than in other soft tissues.

Radioactive strontium belongs to osteotropic biologically hazardous radionuclides. As a pure beta emitter, it poses the main danger when it enters the body. The nuclide is mainly supplied to the population with contaminated products. The inhalation route is less important. Radiostrontium is selectively deposited in the bones, especially in children, exposing the bones and the bone marrow contained in them to constant radiation.

Everything is described in detail in the original article by I.Ya. Vasilenko, O.I. Vasilenko. Radioactive strontium.