Radiation sickness is a complex of general and local reactive changes caused by the effect of increased doses of ionizing radiation on cells, tissues and the environment of the body. Radiation sickness occurs with the phenomena of hemorrhagic diathesis, neurological symptoms, hemodynamic disorders, a tendency to infectious complications, gastrointestinal and skin lesions. Diagnosis is based on the results of dosimetric monitoring, characteristic changes in the hemogram, biochemical blood test, myelogram. In the acute stage of radiation sickness, detoxification, hemotransfusion, antibiotic therapy, and symptomatic therapy are performed.
Radiation sickness is a common disease caused by the influence of radioactive radiation on the body in the range exceeding the maximum permissible doses. It occurs with damage to the hematopoietic, nervous, digestive, skin, endocrine and other systems. Throughout life, a person is constantly exposed to small doses of ionizing radiation emanating from both external (natural and man-made) and internal sources that penetrate the body during breathing, water and food consumption and accumulate in tissues. A., with a normal radiation background, taking into account the above-mentioned factors, the total dose of ionizing radiation usually does not exceed 1-3 mSv (mGr) / year and is considered safe for the population. According to the conclusion of the International Commission on Radiological Protection, radiation sickness may develop if the exposure threshold is exceeded by more than 1.5 Sv/ year or a single dose of 0.5 Sv is received.
Radiation damage can occur due to a single (or short-term) exposure to high intensity or prolonged exposure to low doses of radiation. High-intensity damaging effects are characteristic of man-made disasters in the nuclear power industry, testing or use of nuclear weapons, total irradiation in oncology, hematology, rheumatology, etc. Chronic radiation sickness can develop in medical personnel of radiology and therapy departments (radiologists, radiologists), patients undergoing frequent radiological and radionuclide studies.
The damaging factors can be alpha and beta particles, gamma rays, neutrons, X-rays; simultaneous exposure to various types of radiation energy is possible – the so-called mixed irradiation. At the same time, the neutron flux, X-ray and gamma radiation can cause radiation sickness when exposed externally, whereas alpha and beta particles cause damage only when they enter the body through the respiratory or digestive tract, damaged skin and mucous membranes.
Radiation sickness is the result of damaging effects occurring at the molecular and cellular level. As a result of complex biochemical processes, products of pathological fat, carbohydrate, nitrogen, water-salt metabolism appear in the blood, causing radiation toxemia. The damaging effects primarily affect the actively dividing cells of the bone marrow, lymphoid tissue, endocrine glands, intestinal and skin epithelium, neurons. This causes the development of bone marrow, intestinal, toxemic, hemorrhagic, cerebral and other syndromes that make up the pathogenesis of radiation sickness.
The peculiarity of radiation damage is the absence at the time of direct exposure to heat, pain and other sensations, the presence of a latent period preceding the development of a detailed picture of radiation sickness.
The classification of radiation sickness is based on the criteria of the time of injury and the dose of absorbed radiation. With a single massive exposure to ionizing radiation, acute radiation sickness develops, with prolonged, repeated in relatively small doses, chronic radiation sickness develops. The severity and clinical form of acute radiation injury are determined by the radiation dose:
Radiation injury occurs with simultaneous / short-term irradiation with a dose of less than 1 Gy; pathological changes are reversible.
The bone marrow form (typical) develops with simultaneous / short-term irradiation with a dose of 1-6 Gy. The mortality rate is 50%. It has four degrees:
- (light) – 1-2 Gr
- (medium) – 2-4 Gr
- (heavy) – 4-6 Gr
- (extremely heavy, transitional) – 6-10 Gr
The gastrointestinal form is the result of simultaneous/ short-term irradiation with a dose of 10-20 Gy. It proceeds with severe enteritis, bleeding from the gastrointestinal tract, fever, infectious and septic complications.
The vascular (toxemic) form manifests with simultaneous / short-term irradiation with a dose of 20-80 Gy. It is characterized by severe intoxication and hemodynamic disorders.
The cerebral form develops with simultaneous / short-term irradiation with a dose of more than 80 Gy. The fatal outcome occurs 1-3 days after irradiation from cerebral edema.
The course of a typical (bone marrow) form of acute radiation sickness goes through IV phases:
- I – phase of primary general reactivity – develops in the first minutes and hours after radiation exposure. Accompanied by malaise, nausea, vomiting, arterial hypotension, etc.
- II – latent phase – the primary reaction is replaced by an imaginary clinical well-being with an improvement in the subjective state. It starts from 3-4 days and lasts up to 1 month.
- III – phase of the developed symptoms of radiation sickness; proceeds with hemorrhagic, anemic, intestinal, infectious, etc. syndromes.
- IV – recovery phase.
Chronic radiation sickness in its development goes through 3 periods: formation, recovery and consequences (outcomes, complications). The period of formation of pathological changes lasts 1-3 years. In this phase, a clinical syndrome characteristic of radiation damage develops, the severity of which can vary from mild to extremely severe. The recovery period usually begins 1-3 years after a significant decrease in intensity or complete cessation of radiation exposure. The outcome of chronic radiation sickness may be recovery, incomplete recovery, stabilization of the changes received or their progression.
Acute radiation sickness
In typical cases, radiation sickness occurs in the bone marrow form. In the first minutes and hours after receiving a high dose of radiation, in the first phase of radiation sickness, the victim experiences weakness, drowsiness, nausea and vomiting, dryness or bitterness in the mouth, headache. With simultaneous irradiation at a dose of more than 10 Gy, fever, diarrhea, arterial hypotension with loss of consciousness may develop. From local manifestations, transient erythema of the skin with a bluish tinge may be noted. From the peripheral blood, early changes are characterized by reactive leukocytosis, which is replaced by leukopenia and lymphopenia on the second day. The absence of young cell forms is determined in the myelogram.
In the phase of apparent clinical well-being, the signs of the primary reaction disappear, and the victim’s well-being improves. However, an objective diagnosis determines the lability of blood pressure and pulse, decreased reflexes, impaired coordination, the appearance of slow rhythms according to EEG data. After 12-17 days after radiation damage, baldness begins and progresses. Leukopenia, thrombocytopenia, and reticulocytopenia are increasing in the blood. The second phase of acute radiation sickness can last from 2 to 4 weeks. With an irradiation dose of more than 10 Gy, the first phase can immediately pass into the third.
In the phase of pronounced clinical symptoms of acute radiation sickness, intoxication, hemorrhagic, anemic, infectious, skin, intestinal, neurological syndromes develop. With the beginning of the third phase of radiation sickness, the condition of the victim worsens. At the same time, weakness, fever, and hypotension increase again. Against the background of deep thrombocytopenia, hemorrhagic manifestations develop, including bleeding gums, nosebleeds, gastrointestinal bleeding, hemorrhages in the central nervous system, etc. The consequence of the lesion of the mucous membranes is the occurrence of ulcerative-necrotic gingivitis, stomatitis, pharyngitis, gastroenteritis. Infectious complications of radiation sickness most often include sore throats, pneumonia, lung abscess.
With high-dose radiation, radiation dermatitis develops. In this case, primary erythema forms on the skin of the neck, elbow bends, axillary and inguinal areas, which is replaced by swelling of the skin with the formation of blisters. In favorable cases, radiation dermatitis is resolved with the formation of pigmentation, scarring and compaction of subcutaneous tissue. When the vessels are interested, radiation ulcers and skin necrosis occur. Hair loss is common: there is hair removal on the head, chest, pubis, loss of eyelashes and eyebrows. In acute radiation sickness, there is a deep inhibition of the function of the endocrine glands, mainly the thyroid gland, gonads, and adrenal glands. In the long-term period of radiation sickness, an increase in the development of thyroid cancer was noted.
Gastrointestinal tract damage can occur in the form of radiation esophagitis, gastritis, enteritis, colitis, hepatitis. At the same time, nausea, vomiting, pain in various parts of the abdomen, diarrhea, tenesmus, admixture of blood in the feces, jaundice are observed. Neurological syndrome accompanying the course of radiation sickness is manifested by increasing adynamia, meningeal symptoms, confusion, decreased muscle tone, increased tendon reflexes.
During the recovery phase, well-being gradually improves, and impaired functions are partially normalized, however, anemia and asthenovegetative syndrome persist in patients for a long time. Complications and residual lesions of acute radiation sickness may include the development of cataract, cirrhosis of the liver, infertility, neuroses, leukemia, malignant tumors of various localizations.
Chronic radiation sickness
In the chronic form of radiation sickness, the pathological effects unfold more slowly. The leading ones are neurological, cardiovascular, endocrine, gastrointestinal, metabolic, hematological disorders.
A mild degree of chronic radiation sickness is characterized by nonspecific and functionally reversible changes. Patients feel weakness, decreased performance, headaches, sleep disorder, instability of the emotional background. Among the permanent signs are a decrease in appetite, dyspeptic syndrome, chronic gastritis with reduced secretion, biliary dyskinesia. Endocrine dysfunction in radiation sickness is expressed in a decrease in libido, menstrual disorders in women, impotence in men. Hematological changes are unstable and not pronounced. The course of mild chronic radiation sickness is favorable, recovery without consequences is possible.
With an average degree of radiation damage, more pronounced vegetative-vascular disorders and asthenic manifestations are noted. There are dizziness, increased emotional lability and excitability, weakening of memory, possible attacks of loss of consciousness. Trophic disorders are added: alopecia, dermatitis, nail deformities. Cardiovascular disorders are represented by persistent arterial hypotension, paroxysmal tachycardia. Hemorrhagic phenomena are characteristic of the II degree of severity of chronic radiation sickness: multiple petechiae and ecchymoses, recurrent nasal and gingival bleeding. Typical hematological changes are leukopenia, thrombocytopenia; in the bone marrow – hypoplasia of all hematopoietic sprouts. All changes are persistent.
Severe radiation sickness is characterized by dystrophic changes in tissues and organs that are not compensated by the regenerative capabilities of the body. Clinical symptoms are progressive, intoxication syndrome and infectious complications, including sepsis, are additionally added. There is a sharp asthenization, persistent headache, insomnia, multiple hemorrhages and repeated bleeding, loosening and loss of teeth, ulcerative-necrotic changes of the mucous membranes, total baldness. Changes in peripheral blood, biochemical parameters, and bone marrow are deeply pronounced. With the IV, extremely severe degree of chronic radiation sickness, the progression of pathological shifts occurs steadily and quickly, leading to an imminent fatal outcome.
The development of radiation sickness can be assumed based on the picture of the primary reaction, the chronology of the development of clinical symptoms. Facilitates the diagnosis of establishing the fact of radiation damaging effects and dosimetric control data.
The severity and stage of the lesion can be determined by the change in the picture of peripheral blood. With radiation sickness, there is an increase in leukopenia, anemia, thrombocytopenia, reticulocytopenia, increased ESR. When analyzing biochemical parameters in the blood, hypoproteinemia, hypoalbuminemia, electrolyte disorders are detected. The myelogram shows signs of pronounced hematopoiesis depression. With a favorable course of radiation sickness, the reverse development of hematological changes begins in the recovery phase.
Of auxiliary importance are other laboratory diagnostic data (microscopy of skin and mucous ulcer scrapings, blood culture for sterility), instrumental studies (EEG, electrocardiography, ultrasound of the abdominal cavity, pelvis, thyroid gland, etc.), consultations of narrow-profile specialists (hematologist, neurologist, gastroenterologist, endocrinologist, etc.).
In acute radiation sickness, the patient is hospitalized in a sterile box, providing aseptic conditions and bed rest. Priority measures include decontamination (gastric lavage, enema, skin treatment), administration of antiemetics, elimination of collapse. During internal irradiation, the administration of drugs that neutralize known radioactive substances is indicated. In the first day after the appearance of signs of radiation sickness, powerful detoxification therapy (infusion of saline, plasma-substituting and saline solutions), forced diuresis is carried out. With the phenomena of necrotic enteropathy, hunger, parenteral nutrition, treatment of the oral mucosa with antiseptics are prescribed.
In order to combat hemorrhagic syndrome, blood transfusions of platelet and erythrocyte mass are carried out. With the development of DIC syndrome, transfusion of freshly frozen plasma, plasmapheresis is performed. In order to prevent infectious complications, antibiotic therapy is prescribed. A severe form of radiation sickness, accompanied by bone marrow aplasia, is an indication for its transplantation. In chronic radiation sickness, therapy is mainly symptomatic.
Prognosis and prevention
The prognosis of radiation sickness is directly related to the massiveness of the radiation dose received and the time of the damaging effect. Patients who have survived the critical period of 12 weeks after irradiation have a chance of a favorable prognosis. However, even with non-lethal radiation damage, the victims may subsequently develop hemoblastoses, malignant neoplasms of various localization, and various genetic anomalies may be detected in the offspring.
In order to prevent radiation sickness, persons in the radio emission zone should use personal radiation protection and control equipment, radioprotective drugs that reduce the radiosensitivity of the body. Persons in contact with ionizing radiation sources must undergo periodic medical examinations with mandatory hemogram monitoring.