Manifestations of radiation exposure - radiation sickness. Radiation toxicology Early radiation toxicity

Hiroshima, Nagasaki, Chernobyl - these are black pages in the history of mankind associated with atomic explosions. Negative radiation effects were observed among the affected population. The effect of ionizing radiation is acute, when the body is destroyed in a short time and death occurs, or chronic (irradiation in small doses). The third type of influence is long-term. It causes the genetic effects of radiation.

The impact of ionizing particles is different. In small doses, radioactive radiation is used in medicine to combat oncology. But almost always it negatively affects health. Small doses of atomic particles are catalysts (accelerators) for the development of cancer and the breakdown of genetic material. Large doses lead to partial or complete death of cells, tissues and the whole organism. The difficulty in monitoring and tracking pathological changes lies in the fact that when receiving low doses of radiation, there are no symptoms. The effects can show up years or even decades later.

The radiation effects of human exposure have the following consequences:

• Mutations.
• Cancers of the thyroid gland, leukemia, breast, lungs, stomach, intestines.
• Hereditary disorders and genetic code.
• Metabolic and hormonal imbalance.
• Damage to the organs of vision (cataract), nerves, blood and lymphatic vessels.
• Accelerated aging of the body.
• Ovarian sterility in women.
• Dementia.
• Violation of mental and mental development.

Routes and degree of exposure

Human exposure occurs in two ways - external and internal.

The external radiation that the body receives comes from emitting objects:

• space;
• radioactive waste;
• nuclear weapons testing;
• natural radiation of the atmosphere and soil;
• accidents and leaks at nuclear reactors.

Internal exposure to radiation is carried out from within the body. Radiation particles are found in food products that a person consumes (up to 97%), and in small amounts in water and air. In order to understand what happens to a person after exposure to radiation, you need to understand the mechanism of its effects.

Powerful radiation causes the process of ionization in the body. This means that free radicals are formed in cells - atoms that lack an electron. To make up for the missing particle, free radicals take it away from neighboring atoms. Thus, a chain reaction occurs. This process leads to a violation of the integrity of DNA molecules and cells. As a result - the development of atypical cells (cancerous), massive cell death, genetic mutations.

Radiation doses in Gy (Gray) and their consequences:

• 0.0007-0.002 - the rate of radiation received by the body per year;
• 0.05 - maximum allowable dose for humans;
• 0.1 is the dose at which the risk of developing gene mutations doubles;
• 0.25 - the maximum allowable single dose in emergency conditions;
• 1.0 - development of acute radiation sickness;
• 3-5 - ½ of those affected by radiation die within the first two months due to damage to the bone marrow and, as a result, a violation of the hematopoietic process;
• 10-50 - death occurs in 10-14 days due to damage to the gastrointestinal tract (gastrointestinal tract);
• 100 - death occurs in the first hours, sometimes after 2-3 days due to damage to the central nervous system (central nervous system).

Classification of lesions in radiation exposure

Radiation exposure leads to damage to the intracellular apparatus and cell functions, which subsequently causes their death. The most sensitive cells that divide rapidly are leukocytes, intestinal epithelium, skin, hair, nails. Hepatocytes (liver), cardiocytes (heart) and nephrons (kidneys) are more resistant to radiation.

Radiation Effects of Irradiation

Somatic consequences:

• acute and chronic radiation sickness;
• eye damage (cataract);
• radiation burns;
• atrophy and thickening of the irradiated areas of the skin, blood vessels, lungs;
• fibrosis (growth) and sclerosis (replacement by a connective structure) of soft tissues;
• decrease in the quantitative composition of cells;
• dysfunction of fibroblasts (cell matrix, the basis for its appearance and development).

Somatic-stochastic consequences:

• tumors of internal organs;
• mental retardation;
• congenital deformities and developmental anomalies;
• fetal cancer due to irradiation;
• reduction in life expectancy.

Genetic Consequences:

• change in heredity;
• dominant and recessive gene mutations;
• chromosomal rearrangements (changes in the number and structure of chromosomes).

Symptoms of radiation injury

The symptoms of radiation exposure depend primarily on the radioactive dose, as well as on the area affected and the duration of a single exposure. Children are more susceptible to radiation. If a person has such internal diseases as diabetes mellitus, autoimmune pathologies (rheumatoid arthritis, lupus erythematosus), this will aggravate the effect of radioactive particles.

A single dose of radiation causes more injury than the same dose, but received over several days, weeks or months.

With a single exposure to a large dose or if a large area of ​​the skin is affected, pathological syndromes develop.

Cerebrovascular syndrome

These are signs of radiation exposure associated with damage to the vessels of the brain and impaired cerebral circulation. The lumen of the vessels narrows, the supply of oxygen and glucose to the brain is limited.

Symptoms:

• hemorrhages in the cerebellum - vomiting, headache, impaired coordination, strabismus in the direction of the lesion;
• hemorrhage in the bridge - the eyes do not move to the sides, they are located only in the middle, the pupils do not dilate, the reaction to light is weak;
• hemorrhage in the thalamus - complete paralysis of half of the body, the pupils do not react to light, the eyes are lowered to the nose, the outcome is always fatal;
• subarachnoid hemorrhage - sharp intense pain in the head, aggravated by any physical movements, vomiting, fever, changes in heart rhythms, fluid accumulation in the brain with subsequent edema, epileptic seizures, repeated hemorrhages;
• thrombotic stroke - impaired sensitivity, deviation of the eyes to the lesion, urinary incontinence, impaired coordination and purposefulness of movements, mental retardation, steady repetition of phrases or movements, amnesia.

Gastrointestinal syndrome

Occurs if a person is irradiated with a dose of not 8-10 Gy. This is typical for patients with the 4th degree of acute radiation sickness. It appears no earlier than 5 days.

Symptoms:

• nausea, loss of appetite, vomiting;
• bloating, intense diarrhea;
• violation of the water-salt balance.

Subsequently, necrosis develops - necrosis of the intestinal mucosa, then sepsis.

Syndrome of infectious complications

This condition develops due to a violation of the blood formula, as a result, a decrease in natural immunity. The risk of exogenous (external) infection increases.

Complications of radiation sickness:

• oral cavity - stomatitis, gingivitis;
• respiratory organs - tonsillitis, bronchitis, pneumonia;
• Gastrointestinal - enteritis;
• radiation sepsis - pus formation intensifies, pustules appear on the skin and internal organs.

Oropharyngeal syndrome

This is an ulcerative bleeding lesion of the soft tissues of the oral and nasal cavities. The victim has edematous mucosa, cheeks, tongue. The gums become loose.

Symptoms:

• severe pain in the mouth, when swallowing;
• a lot of viscous mucus is produced;
• respiratory failure;
• development of pulmonitis (damage to the alveoli of the lungs) - shortness of breath, wheezing, ventilation failure.

Hemorrhagic syndrome

Determines the severity and outcome of radiation sickness. Blood clotting is disturbed, the walls of blood vessels become permeable.

Symptoms - in mild cases, small, pinpoint hemorrhages in the mouth, in the anus, on the inside of the legs. In severe cases, radiation exposure causes massive bleeding from the gums, uterus, stomach and lungs.

Radiation damage to the skin

At small doses, erythema develops - a pronounced reddening of the skin due to the expansion of blood vessels, later necrotic changes are observed. Six months after irradiation, pigmentation appears, proliferation of connective tissue, persistent telangiectasias appear - expansion of capillaries.

Human skin after radiation atrophies, becomes thin, easily damaged by mechanical action. Radiation burns of the skin are not treatable. The skin does not heal and is very painful.

Genetic mutations from exposure to radiation

Another sign of radiation exposure is gene mutations, a violation of the structure of DNA, namely one of its links. Such an insignificant, at first glance, change leads to serious consequences. Gene mutations irreversibly change the state of the organism and in most cases lead to its death. The mutant gene causes such diseases - color blindness, idiopathy, albinism. appear in the first generation.

Chromosomal mutations - a change in the size, number and organization of chromosomes. Their areas are being restructured. They directly affect the growth, development and functionality of internal organs. Carriers of chromosomal breakdowns die in childhood.

Consequences of exposure to radiation on a global scale:

1. The fall in the birth rate, the deterioration of the demographic situation.
2. The rapid growth of oncological pathology among the population.
3. A trend towards deteriorating health of children.
4. Serious violations of the immune status among the child population, which is located in the zones of influence of radiation.
5. A marked reduction in average life expectancy.
6. Genetic failures and mutations.

A significant part of the changes caused by the influence of radioactive particles is irreversible.

The risk of cancer after radiation exposure is directly proportional to the radiation dose. Radiation, even in minimal doses, negatively affects the well-being and functioning of internal organs. People often attribute their condition to chronic fatigue syndrome. Therefore, after diagnostic or therapeutic measures associated with radiation, it is necessary to take measures to remove it from the body and strengthen the immune system.

radiation damage- pathological changes in the body, organs and tissues that develop as a result of exposure to ionizing radiation. During radiation therapy, general and local radiation injuries are noted. General reactions are early changes. Local radiation damage in the area of ​​local exposure is divided into early and late. Conventionally, early radiation injuries include changes that developed during radiation therapy and within 100 days after its completion. The radiobiological rationale for these timings includes the time needed to repair sub-lethal injuries. Radiation damage that appears after 3 months, often many years after radiation therapy, is called late, or long-term, effects of radiation.

In the process of radiation treatment, radiation reactions may appear - changes that often disappear within 2-4 weeks without treatment.

In some patients, only early or only late local radiation injuries are noted. The clinical manifestation and course of radiation damage are determined by the magnitude and time distribution of the total absorbed dose, as well as by the tolerance of tissues in the irradiated volume and, apparently, by individual sensitivity.

Currently, the types of normal tissues are divided into the so-called hierarchical, or H-type (from English hierarchy), and flexible, or F-type (from English flexible). The first type of tissue is distinguished by the nature of the cells: stem cells, growth fractions, postmiotic mature cells. The processes during irradiation proceed quickly in them, they are responsible for the appearance of early radiation damage. These include hematopoietic cells, mucous membranes, epithelium of the small intestine. Tissues of the second type consist of cells in which renewal processes are slow. These include tissues of the kidney, liver, cells of the central nervous system. When flexible tissues are irradiated, late radiation damage occurs.

The appearance of early radiation damage is associated with functional circulatory disorders, radiation cell death, and a decrease in repair processes in healthy tissues surrounding the tumor. Early

injuries to a small extent depend on the dose per fraction, have an α/β ratio of more than 10 Gy, while shortening the total time of the course of exposure leads to an increase in their frequency and severity. But early damage can quickly regress. Their appearance does not always indicate the occurrence of late radiation damage over time.

With the development of late radiation damage, morphological changes in blood and lymphatic vessels are revealed. Gradually, these changes lead to obliteration and thrombosis of blood vessels, sclerotic and other changes. The appearance of late radiation injuries occurring 3 months after the end of treatment depends on the dose per fraction, is characterized by the value of the α/β ratio from 1 to 5 Gy, and has no connection with the duration of the course of irradiation. Late radiation damage usually requires treatment, although tissue changes are almost irreversible.

The level of necessary tumoricidal doses often exceeds the level of tolerance of the tissues and organs surrounding the tumor.

Tolerant doses of gamma radiation for various organs and tissues with dose fractionation of 2 Gy 5 times a week (cited by M. S. Bardychev, 1996)

The main factors influencing the occurrence and severity of radiation damage include the magnitude and rate of the absorbed dose; dose fractionation regimen; volume of irradiated healthy tissues; the initial state of the body, irradiated tissues - concomitant diseases.

An increase in the total dose leads to an increase in the risk of radiation damage. The dose rate is also directly (but not linearly) related to the likelihood of late damage. The fractionation mode significantly affects the prognosis of radiation damage. Lower-

single dose reduction, daily dose splitting, and the use of split courses of irradiation reduce the appearance of late radiation injuries. Concomitant diseases that are accompanied by a deterioration in trophic processes in tissues, such as diabetes mellitus, anemia, as well as chronic inflammatory processes in organs that fall into the irradiation zone, significantly increase the risk of radiation damage.

Currently, the classification of the Radiotherapy Oncology Group, jointly with the European Organization for Research and Treatment of Cancer (RTOG / EORG, 1995), is considered the most complete. The classification is supplemented by the Criteria of the Cooperative Investigation Group to more accurately characterize predominantly early toxic effects, since modern radiotherapy is usually used in combination with introductory, simultaneous or adjuvant chemotherapy. In the classification, injuries are assessed on a six-point scale from 0 to 5, taking into account the severity of their manifestations, while the symbol "0" corresponds to the absence of changes, and "5" - the death of the patient as a result of radiation damage.

Acute radiation injury (RTOG)

Continuation of the table.

Continuation of the table.

The end of the table.

RTOG/EORTC Late Radiation Injury Rating Scale

Table continuation

The end of the table.

Prevention of radiation damage includes a rational choice of the type of radiation energy, taking into account the features of the distribution of energy in the irradiated volume, as well as distribution in time, the use of radio modifiers. Preventive measures include the mandatory treatment of chronic concomitant diseases, the appointment of vitamins, enzymes, natural or artificial antioxidant drugs. Local prophylaxis involves not only the treatment of chronic processes in organs that fall into the scope of irradiation, but also additional exposure to drugs that improve tissue trophism. Treatment of early radiation reactions is important. The protective effect of the rational use of radio modifiers has been proven.

Treatment of late radiation injuries. Treatment of late radiation injuries skin is built taking into account the clinical form of damage. The use of low-intensity laser radiation is highly efficient. Apply steroid and fortified oils. In the treatment of radiation fibrosis, absorbable drugs are used: dimethyl sulfoxide, lidase, glucocorticoids. Sometimes it is necessary to resort to radical excision of damaged tissues, followed by skin-plastic replacement of the defect. Currently, radiation damage to the skin is associated with errors in planning and conducting radiation therapy.

To treat lesions oral mucosa natural or artificial antioxidant preparations are used: tocopherol, ascorbic acid, eleutherococcus extract, triovit preparations, ionol, dibunol, mexidol. Be sure to prescribe a sparing diet, antibacterial (taking into account individual sensitivity) and antifungal therapy.

During radiation therapy for cancer larynx it is advisable to gargle with antiseptic agents, inhalations with anti-inflammatory and mucosal reparation-improving drugs.

In the treatment of radiation pulmonitis the most effective are the use of inhalations of a 15-20% solution of dimethyl sulfoxide, active antibiotic therapy, expectorants, bronchodilator therapy, general restorative treatment.

Treatment of radiation damage hearts carried out according to the general principles of cardiology, depending on the type of manifestation of complications - treatment of rhythm disturbances, ischemic changes, symptoms of heart failure.

With radiation esophagitis it is recommended to take fresh butter, sea buckthorn oil or olive oil before meals.

Local treatment of radiation injuries guts aimed at reducing inflammatory processes in the damaged area of ​​the intestine and at stimulating reparative processes. According to the recommendations of M. S. Bardychev, the author of numerous works on the prevention and treatment of radiation injuries, it is necessary to apply cleansing enemas with a warm infusion of chamomile decoction for a week, then for 2-3 weeks in the morning and evening, taking into account the level of damage 50-75 - percentage solution

dimexide in combination with 30 mg of prednisolone. In the next 2-3 weeks, oil microclysters, ointments of methyluracil, caratoline, rosehip oil or sea buckthorn are prescribed. Intense pain in the rectum should be stopped with methyluracil suppositories with novocaine, anesthesin, platifillin and prednisolone. Rectovaginal or vesicovaginal fistulas up to 1 cm in diameter usually close within 6 to 12 months with this treatment. With rectal fistulas of a larger diameter, an operation is necessary to remove the sigmoid colon with the formation of an artificial anus. In case of formation of stenoses in the irradiated segments of the small or large intestine in the long term, appropriate surgical treatment is carried out.

For the prevention of subdiaphragmatic sections arising from irradiation diarrhea astringents and absorbents are recommended (astringent collection, starch, activated carbon, enterosorbents), and imodium is used to stop it. For removal nausea And vomiting antiemetics are effective in combination with sedatives and vitamins of group B. Antioxidants - vitamins A (100,000 units / day), C (1-2 g 2 times a day) are also indicated. To normalize bowel function and prevent dysbacteriosis, enzyme preparations (festal, enzistal, mezim forte) and bifidumbacterin (hilak-forte, vita-flor, etc.) are prescribed. A rational and sparing diet is recommended with the exclusion of all irritating foods (spicy, salty, fried, spices, spirits, etc.).

Radiation treatment cystitis includes intensive anti-inflammatory therapy and stimulation of reparative processes. Treatment consists in the use of antibiotics in accordance with individual sensitivity, instillations into the bladder of antiseptic solutions and agents that stimulate reparative processes (solutions of proteolytic enzymes, 5% dimexide solution, 10% dibunol or methyluracil). If ureteral stenosis occurs, bougienage is performed or stents are installed. With an increase in hydronephrosis and the threat of uremia, the imposition of a nephrostomy is indicated.

In the treatment of radiation cystitis and rectitis, the addition of standard treatment regimens with low-intensity laser irradiation increased the effectiveness of the treatment of radiation injuries of the bladder and rectum.

Radiation lymphostasis and elephantiasis of the extremities often develop as a result of irradiation of regional lymphatic collectors or when radiation treatment is combined with surgery (when regional lymphatic collectors are removed). The treatment consists in restoring the lymphatic drainage pathways with the help of microsurgical lymphovenous shunting.

Emphasis should be placed on maintenance non-specific drug therapy with high-field irradiation. To combat pancytopenia, appropriate hemostimulating therapy (dexamethasone, colony-stimulating factor preparations) is prescribed. All patients are shown the appointment of antiplatelet agents and drugs that improve

microcirculation (trental, chimes, teanicol, aescusan). Low-intensity systemic laser therapy is also effective for stopping radiation reactions.

In terms of reducing the risk of radiation damage, strategic approaches to the use of methods and means that reduce the impact of post-radiation effects on normal tissues, such as laser radiation, hypoxic therapy, and other radioprotectors and immunomodulators, are important.

Radiation toxicology studies the distribution, exchange kinetics, and biological effects of radioactive isotopes. This information is used in practice to establish and evaluate the maximum allowable levels of content and intake of radioactive isotopes in the body by air, water and food.

Irradiation when radioactive isotopes enter the body continues continuously until the isotope completely decays or is removed from the body. Sometimes exposure lasts for years or even for the life of the victim. In this case, predominant irradiation of individual organs and systems of the body is most often observed.

The degree of toxicity and the specificity of the biological action of a radioactive isotope is determined by its physical (type and energy of radiation, half-life, emitter dose), chemical (form of the administered compound, solubility at pH of tissues and organs, degree of affinity for tissue structures) and physiological (path of entry, magnitude and the rate of absorption of the radionuclide from the depot, the nature and type of distribution, the rate of excretion from the body) properties, as well as the degree of radiosensitivity of the object under study.

Biologically active amounts of most radioactive isotopes are of negligible weight. The amount of Sr90 corresponding to 1 curie weighs 6.9 10 -3 g, and the maximum allowable dose (2 microcuries) is only 1.4 10 -8 g. The damaging effect of radioactive isotopes is caused not by their chemical properties, but by radiation during decay . Only in very slowly decaying radioactive isotopes (U238, Th232, etc.) does not radiation, but chemical toxicity come to the fore. Radioactive isotopes can enter the body through the lungs (inhalation of aerosols, vapors, smoke), the gastrointestinal tract (with water and food), skin and wounds. For diagnostics and therapy, in addition to those listed, subcutaneous, intramuscular, intraperitoneal and interstitial administration of isotopes is used.

When inhaled, radioactive aerosols, passing through the respiratory tract, partially settle in the nasopharynx and oral cavity, and from there they may enter the digestive tract; particles of a certain size and gases enter the lungs. As a result of the activity of the ciliated epithelium, a certain proportion of the particles is removed from the respiratory tract and also, due to ingestion, enters the gastrointestinal tract.

The degree of penetration, the magnitude and duration of retention of aerosols in the lungs depend on their charge, particle size and properties of the inhaled compound. In the case of inhalation of poorly soluble compounds under conditions optimal for retaining aerosols in the lungs (particle size> 0.5≤2 microns), about 25% of the radioactive substance is immediately removed with exhaled air, 50% is retained in the upper respiratory tract and removed within a few hours as a result of the activity of the ciliated epithelium. Of the 25% of aerosols that have entered the lower respiratory tract, 10% are quite quickly, also due to the activity of the ciliated epithelium, removed from the lungs, enter the oral cavity and are swallowed.

The remaining 15% slowly disappear from the lungs. Most of the remaining activity is retained in the lungs or phagocytosed and enters the lymph nodes of the lungs, where it is firmly fixed. As a result, as well as the small volume of the lymph nodes compared to the mass of the lungs, the concentration of poorly soluble radioactive aerosols in the lymph nodes in the late periods after inhalation of the isotope can be 100-1000 times higher than that in the lungs. Highly soluble compounds of radioactive substances are quickly absorbed from the lungs and, depending on their properties, are distributed in the body in various ways. The absorption of radioactive isotopes from the gastrointestinal tract depends on the chemical properties of the administered compound and the physiological state of the organism. With rare exceptions (tritium oxide), radioactive isotopes are poorly absorbed through intact skin.

The distribution in the body of isotopes of elements belonging to the same group of the periodic system has much in common. Elements of the I main group (Li, Na, K, Rb, Cs) are completely resorbed from the intestine, relatively evenly distributed throughout the organs, and relatively quickly excreted in the urine. Elements of group II (Ca, Sr, Ba, Ra) are well absorbed from the intestines, selectively deposited in the skeleton, and excreted in a slightly larger amount with feces than with urine. Elements III of the main and IV side groups, including light lanthanides, actinides and transuranium elements, are practically not absorbed from the intestine, but, getting into the blood in one way or another, they are selectively deposited in the liver and, to a lesser extent, in the skeleton. They are excreted mainly with feces. Elements V and VI of the main groups, with the exception of polonium, are relatively well absorbed from the intestine and excreted almost exclusively (up to 70-80%) in the urine during the first day, therefore, they are deposited in the organs in a relatively small amount.

The decrease in radioactivity in organs occurs as a result of radioactive decay, the redistribution of isotopes in the body or excretion from it. These processes occur simultaneously and independently of each other.

The physical decay of radioactive isotopes (see) obeys an exponential law, which means the constancy of the proportion of radioactive atoms decaying per unit time. The period of time during which the initial radioactivity of an isotope is halved is called the physical half-life.

An exponential or power-law model is used to describe the kinetics of isotope elimination from organs and tissues and from the organism as a whole. In the first case, to calculate the amount of the isotope in the body, it is assumed that it is released at a constant rate, i.e., a certain proportion of the isotope present in the body is released per unit of time. The removal of an isotope is most often described by the sum of two or more exponentials. This indicates that in the organ or tissue there are several fractions of the isotope, which have different bond strengths with tissue structures and different excretion rates.

In the power model, the amount of the isotope retained in the body is calculated as a function of the time elapsed since the isotope entered the body. The mathematical equations describing this dependence are found empirically for each isotope.

The rate of excretion of a radioactive substance from the body (or organ) is characterized by the biological half-life, i.e., the time during which the radioactivity is halved only due to the removal of the substance. The length of time during which the radioactivity in the body is reduced by half due to radioactive decay and excretion of the substance from the body is called the effective half-life.

The toxicity of radioactive substances, as a rule, is estimated by the amount of radioactivity per unit weight of the animal (µcurie/g, µcurie/kg, etc.). The biological effect, however, is more conveniently associated with the absorbed dose in tissues, organs and the body as a whole, measured in rads (see Doses of ionizing radiation). The dose value in rads can be calculated from data on the amount of the isotope per unit weight of the tissue, knowledge of its decay pattern, i.e., the type and energy of the radiation and the effective half-life.

The clinical picture of the lesion, caused by radionuclides well absorbed from the injection site (Sr89, Sr90, Ba140, Cs137, Ra226, H3), does not depend on the route of their entry into the body. In the case of radioactive isotopes that are poorly resorbed from the depot (Y91, Y90, Ce144, Pu239, Po210), the lesion is largely determined by the method of administration of the substance and is characterized by the predominance of pathological processes at the site of isotope administration.

When hit by radioactive isotopes, evenly distributed in the body, the clinical picture of radiation injury is basically the same as when exposed to external sources of radiation. In case of damage caused by the ingress of radioactive isotopes, selectively deposited in the bone tissue and liver, changes associated with the site of exposure to the emitter come to the fore. In particular, the occurrence of bone tumors, leukemia, cirrhosis and liver neoplasms is characteristic.

Considering that the biological effect of radioactive isotopes that have entered the body can be eliminated only after they are removed from the body, and the possibilities for accelerating this process are still very limited, the prevention of poisoning by radioactive isotopes is of paramount importance (see Radiation hygiene). Therapy of lesions caused by radioactive isotopes is reduced to measures that reduce their absorption from the gastrointestinal tract, accelerate their excretion from the body with the help of various complexing agents and treat intoxication.

After the accident at the Fukushima-1 nuclear power plant, many people (working at the plant and in the vicinity, as well as living in the surrounding area) faced the risk of radiation contamination. In such situations, it is simply necessary to know its symptoms.

After the accident at the Fukushima-1 nuclear power plant, many people (working at the plant and in the vicinity, as well as living in the surrounding area) faced the risk of radiation contamination. In such situations, it is simply necessary to know its symptoms.

1. Nausea and vomiting

The earliest signs of radiation contamination are vomiting and disorientation. If vomiting starts within an hour of being exposed to radiation, then you have received a large dose and, without medical intervention, the risk of death is enormous.

2. Appearance of untreated ulcers on the body

Radiation reduces the number of platelets responsible for blood clotting. As a result, non-healing ulcers and wounds appear on the body. It mainly manifests itself as a rash or spots caused by subcutaneous bleeding.

3. Bleeding

Also, due to the inability of the blood to clot, unexpected bleeding from the nose, mouth, and rectum can occur.

4. Diarrhea and vomiting with blood

The symptoms are the same as described above, but the cause is somewhat different. Radiation thins the walls of the intestines and stomach, inflammation begins and, as a result, stools and vomiting with blood.

5. Radiation burns

The first sign of the so-called skin radiation syndrome is itching. On the affected skin, redness, blisters and open wounds may appear, later the skin begins to peel off.

6. Hair loss

The radiation damages the hair follicles, causing the hair to fall out.

7. Headache, weakness and fatigue

Due to the anemia that occurs when blood is lost, weakness and fainting may occur. It also leads to hypotension or extremely low blood pressure.

8. Wounds in the mouth and on the lips

Radiation destroys bone marrow and white blood cells, leading to an increased risk of bacterial, viral, and fungal infections. This, ultimately, is what kills those suffering from radiation sickness.

1
1 LDC MIBS LLC, St. Petersburg
2 MIBS-Medical Institute named after Berezina Sergey, St. Petersburg; FSBEI HE "St. Petersburg State University"
3 MIBS-Medical Institute. Berezina Sergey, St. Petersburg; FGBOU VO SZGMU them. I. I. Mechnikov of the Ministry of Health of Russia, St. Petersburg
4 LDC MIBS im. S. Berezina, St. Petersburg; FGBOU VO "North-Western State Medical University im. I.I. Mechnikov" of the Ministry of Health of Russia, St. Petersburg

Target: to evaluate the results of the treatment of patients with lung neoplasms of various nature and sizes in the MIBS clinic using two types of linear accelerators.
Material and methods: from December 2011 to February 2017, 71 patients were treated with a total number of primary and metastatic lung lesions of 103. Of all neoplasms, 37 were central, 66 were peripheral; patients treated for primary lung tumors were denied surgical treatment. The treatment was carried out on two types of linear accelerators: CyberKnife (SK) (out of 64 neoplasms for 38 (59.4%) using the Synchrony respiration tracking system) and TrueBeam STx (TB) (on the area of ​​39 neoplasms using the Gating respiration tracking system ).
results: observation group consisted of 50 patients with 71 lung lesions. The average tumor volume was 44.7 cm3 (0.2-496.5 cm3). The median follow-up was 7 months. (1–57 months). Local control was achieved in 100% of cases, the median duration of control was 6 months. (1–57 months). Local control was maintained in most cases of systemic progression of the underlying disease. For 19 (26.8%) formations, the results of treatment achieved a complete response, the median of which was 5 months. (1–47 months). Continued growth was observed in 16 (22.5%) cases, 15 of which were primary tumors. The frequency of early toxicity (cough, shortness of breath) during treatment with CK was lower (8% versus 19% with TB), in most patients it did not exceed grade II, complications of grade III toxicity were observed in 5 patients. The frequency of late radiation complications did not differ in patients treated with both linear accelerators and did not exceed grade II in all patients. Early and late radiation complications of IV degree were not observed in any patient. The 1-, 2-, and 3-year overall survival rates were 83.6%, 77.3%, and 65.8%, respectively.
Conclusion: stereotactic radiation therapy allows achieving and maintaining local control in most patients with a fairly low incidence of radiation complications. When irradiating primary lung tumors, higher doses may be more effective in achieving and maintaining local control.

Keywords: stereotactic radiation therapy, non-small cell lung cancer, lung metastases.

For citation: Martynova N.I., Vorobyov N.A., Mikhailov A.V., Smirnova E.V., Gutsalo Yu.V. The use of stereotactic radiation therapy in patients with primary and metastatic lung tumors // RMJ. 2017. No. 16. pp. 1169-1172

The use of stereotactic radiation therapy in patients with primary and metastatic lung tumors
MartynovaN.I. 1 , Vorob "ev N.A. 1 - 3 , Mikhailov A.V. 1 , Smirnova E.V. 1 , 3 , Gutsalo Yu.V. 1

1 Medical and Diagnostic Center of International Institute of Biological Systems named after Berezin Sergei, St. Petersburg
2 Saint Petersburg State University
3 North Western State Medical University named after I.I. Mechnikov, St. Petersburg

This study illustrates the evaluation of the treatment of patients with lung neoplasms of various nature and sizes in the IIBS clinic performed on two types of linear accelerators.
Patients and methods: from December 2011 to February 2017, 71 patients with a total of 103 primary and metastatic formations of the lungs were treated. Of all the tumors, 37 were central and 66 were peripheral; patients treatment receiving for primary lung tumors were refused a surgical treatment. Treatment was carried out on two types of linear accelerators: CyberKnife (CK) (with the use of the Synchrony Breathing System for 38 (59.4%) out of 64 tumors) and TrueBeam STx (TB) (with the use of the Gating Breathing System on the area of ​​39 tumors).
Results: the observation group consisted of 50 patients with 71 lung formations. The average volume of tumors was 44.7 cm3 (0.2-496.5 cm3). Median observation was 7 months (1-57 months). Local control was achieved in 100% of cases, median duration of control was 6 months (1-57 months). Local control was maintained even in most cases of systemic progression of the underlying disease. For 19 (26.8%) formations, according to the results of treatment, a complete response was achieved, the median of which was 5 months (1-47 months). Continued growth was observed in 16 (22.5%) cases, 15 of which were primary tumors. The frequency of early toxicity (cough, dyspnea) in CK treatment was lower (8% vs. 19% for TB), most patients did not exceed grade II severity, complications of grade III toxicity were observed in 5 patients. The frequency of late radiation complications did not differ in patients receiving treatment on both linear accelerators and did not exceed the grade II in all patients. Early and late radiation complications of grade IV were not observed in any patient. 1-, 2- and 3-year overall survival was 83.6, 77.3 and 65.8%, respectively.
Conclusion: stereotactic radiotherapy allows to achieve and maintain local control in the majority of patients at a sufficiently low incidence of radiation complications. When irradiating primary lung tumors, higher doses may be more effective in achieving and maintaining local control.

key words: stereotactic radiation therapy, non-small cell lung cancer, metastases to the lungs.
For quote: Martynova N.I., Vorob "ev N.A., A.V. Mikhailov et al. The use of stereotactic radiation therapy in patients with primary and metastatic lung tumors // RMJ. 2017. No. 16. P. 1169–1172.

The article is devoted to the possibilities of using stereotactic radiation therapy in patients with primary and metastatic lung tumors.

Lung cancer is the most common oncological disease among the adult population, and metastatic lung disease occurs in most oncological diseases of other localizations. Currently, the standard of care for early stages of primary non-small cell lung cancer is surgery, and in the case of metastatic lung disease, chemotherapy or lung resection. Stereotactic radiotherapy (SRT) is an alternative treatment for patients with a localized disease who are not amenable to surgery. There are studies showing the high efficacy of SLT with a low complication rate in patients with primary and metastatic lung lesions. Today, SLT is a common treatment method, with high efficacy and moderate toxicity. The use of SLT in malignant tumors is described in international guidelines for the treatment of oncological diseases, but, unfortunately, this technique is not widely used in the Russian Federation. Our study reflects our own experience with the use of SLT in lung neoplasms.

Material and methods

In the period from December 2011 to April 2017 in the Department of Radiation Oncology of the Medical Institute. Berezin Sergey treated 71 patients with primary and metastatic lung tumors in the volume of high-dose SLT. The mean age of the patients was 60.9 years (19–90 years). Data on patients are presented in Table 1. 103 neoplasms were exposed to irradiation, of which 33 (32%) were primary tumors of the lung, 70 (68%) were metastases of tumors of various localizations: lung - 25 (24%), urinary tract - 10 (9 .7%), melanoma - 5 (4.8%), colon cancer - 12 (11.6%), other (PNET, non-seminoma) - 5 (4.8%). The percentage of neoplasms by histological type is shown in the diagram (Fig. 1).

Among primary lung tumors, 42.3% was squamous cell carcinoma, 57.7% was adenocarcinoma. Surgical treatment was denied to patients with a primary lung tumor due to severe comorbidities. One patient with primary squamous cell lung cancer and process stage cT3N0M0 refused surgical treatment. Previously, 8 patients received radiation therapy in the conventional mode to the lung and/or mediastinal region: five received radiation therapy for primary lung cancer (including after the surgical stage), one for mediastinal lymphoma. Two patients received adjuvant radiation therapy after resection of metastases of a primitive neuroectodermal tumor in the lungs.
The treatment was carried out on two types of linear accelerators: TrueBeam STx (TB) (39 (37.9%) neoplasms using IMRT and VMAT techniques) and CyberKnife (CK) (64 (62.1%) neoplasms).
The principle of the CK linac dose delivery method is to sequentially deliver low dose beams that intersect at the target to produce a sharp dose reduction gradient beyond the target volume (the so-called "pencil" beam). To determine the volume of exposure at the planning stage, the position of the target at all points of the respiratory cycle, determined using 4D-CT, was taken into account. The target dose for 26 (40.6%) tumors was administered to a volume composed of the sum of all target displacements over a complete respiratory cycle (or ITV, internal tumor volume). When irradiating 38 (59.4%) neoplasms, in order to reduce the amount of irradiation, the Synchrony moving target control system was used, which allows tracking and predicting the change in the position of the target directly during treatment.
Treatment on the TrueBeam STx device was carried out using the breath tracking system in 100% of cases. Patients were positioned according to laser marking and X-ray data. All patients underwent Cone Beam Computed Tomography (CBCT) before each treatment. Nine patients underwent irradiation of 3 to 5 formations simultaneously.
The effect was assessed by CT data. MRI was used in case of involvement of soft tissue structures. The first control after the treatment was carried out one month after treatment, then every 3 months. during the first year, then every 6 months. In case of suspected progression of the disease, as well as in controversial cases, the patient was prescribed an additional examination in the scope of PET-CT.

results

The observation group consisted of 52 patients with 81 lesions in the lungs, of which 18 patients were exposed to radiation only primary lesions, 30 patients had metastases of tumors of various localizations, four received treatment for both primary and metastatic lesions of the lungs. The mean CTV volume was 44.7 cm3 (0.2–496.5 cm3). The total focal dose from 30 to 60 Gy was administered in 3–10 fractions. The most frequent fractionation regimen in the treatment of central tumors was 8 × 7.5 Gy (total equivalent dose 87.6 Gy at α / β = 10), for peripheral lesions - 3 × 15 Gy (total equivalent dose 93.8 Gy at α /β=10). The median follow-up was 7 months. (1–57 months). Local control was achieved in 100% of cases, with a median duration of local control of 6 months. (1–57 months). In 19 (26.8%) formations, a complete response was achieved as a result of treatment, the median duration of which was 5 months. (1–47 months). Progression of the disease in the form of continued growth after treatment was observed in 17 (22.5%) cases, 15 of which developed a relapse of squamous cell lung tumor. The appearance of new foci was noted in 29 patients, while in 27 (93%) of them, local control (control over the irradiated lesion) was maintained throughout the entire observation period. A comparative evaluation of the effectiveness of the treatment performed on the TB and CK devices revealed a slight advantage in achieving a complete response in the treatment on the CK device (27% vs. 23% on the TB device, p<0,05). Среднее время до достижения полного регресса оказалось сравнимым (в среднем 10 мес. на обоих линейных ускорителях). Ранняя токсичность проявлялась кашлем, одышкой, гипертермией, при лечении на CK оказалась ниже, чем на TB (8% против 19%, p<0,05), и у большинства пациентов не превышала II степени. Ранняя токсичность III степени тяжести наблюдалась у 5 пациентов с объемом образований более 200 см3, расположенных центрально. Частота поздних лучевых осложнений (постлучевой пневмонит, постлучевой фиброз, кашель) не различалась у пациентов, получающих лечение на обоих линейных ускорителях, и не превышала II степени у всех 9 пациентов. Ранних и поздних лучевых осложнений IV степени не наблюдалось ни у одного пациента. Общая 7-месячная выживаемость составила 89,8% (рис. 2).

Discussion

Based on our own experience and taking into account the literature data, we can conclude that SLT allows achieving and maintaining local control in most patients at the level of early toxicity of I–II degrees. Among patients with volumetric lung lesions, a large group consisted of patients who were denied surgical treatment due to the high risk of postoperative complications. The median age was 65 years, while in the majority of elderly patients, comorbidities not only worsen the quality of life, but also limit the use of surgical treatment. In addition, some of them have already received treatment for primary tumors. For such patients, treatment in the amount of conventional radiation therapy is widely used. A total dose of 60–66 Gy, 2 Gy per fraction, is applied to the area of ​​the tumor and regional lymph nodes (lymph nodes of the mediastinum) for 6–7 weeks. At the same time, the 5-year cancer-specific survival rate was about 30%, and the main cause of progression and death was the loss of local control. In our study, SLT in the area of ​​lung cancer metastases was performed in 15 patients who had previously undergone radical treatment for the primary tumor, including pulmonectomy. When oligometastases or a new primary tumor appear in a single lung, surgical treatment is not possible. For this category of patients, SLT may be the method of choice, allowing not only to safely administer effective doses in a short time, but also to obtain results comparable to surgical treatment.
SLT is actively used in the treatment of localized lung cancer in inoperable cases, according to the NCCN recommendations. Nevertheless, its use is also possible in patients with a widespread tumor process. This is especially important in cases of tumor localization near the esophagus, trachea and large bronchi, the apex of the lung. Local control of the irradiated foci in such cases helps to avoid complications such as compression or germination of the wall of a hollow organ or the brachial plexus and chest wall.
At the moment, we are conducting an intermediate evaluation of the results obtained. The overall 5- and 7-month survival rates were 92.9% and 89.8%, respectively. In all cases, the death of patients was associated with systemic progression of the disease.
After treatment, 12 patients showed signs of continued growth of 17 lesions, 15 of which had the histological structure of squamous cell lung cancer (5 - primary tumor; 10 - metastases). The median time to progression was 7 months. (2–36 months). Local control in squamous cell carcinoma is lower than in tumors of a different histological structure (Fig. 3). The analysis did not show a significant relationship between the applied dose and the duration of local control among all irradiated formations, and there was also no relationship between the value of the summed total equivalent dose and the duration of local control among primary lung formations. The volume of tumors did not significantly affect the duration of local control and the frequency of local relapses. When analyzing data on primary squamous cell tumors, a negative linear dependence of the summed total equivalent dose and the probability of recurrence was revealed (p=0.01, 86.8%). The same relationship persisted for all squamous formations (p=0.012, 46%). The volume of tumors also did not affect the duration of local control and the frequency of local recurrences.


None of the patients during the entire observation period had toxicity exceeding grade III. The technique has shown itself to be safe when irradiating large volumes of tumors, which makes it possible not only to achieve local control, but also to deliver high doses in the case of palliative treatment.

Conclusion

In accordance with the literature data and on the basis of our experience, we believe that in the presence of contraindications to surgical treatment, SLT allows achieving and maintaining local control in most patients with various volumes of tumor formations with a low incidence of radiation complications. When irradiating squamous cell lung tumors, high doses and/or other modes of hypofractionation (with an increase in the total equivalent dose within the tolerance of the surrounding tissues) may be more effective in achieving and maintaining local control.

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