What Are the Effects of Radiation Therapy on the Brain?

Radiation damage

Radiation damage is damage to body tissue caused by radiation exposure. In general, radiation is high-energy electromagnetic waves or high-energy particles produced by natural or artificial energy sources. Tissue damage can be caused by momentary irradiation of large doses of radiation or prolonged exposure of low doses of radiation. The harmful effects of some rays last only a short time, while others can cause chronic diseases. Significant early damage occurs within minutes or days of exposure to high-dose radiation, while long-term effects are not apparent for weeks, months, or even years. If someone is irradiated with mutations in the genetic material of their germ cells, children born after pregnancy may develop a genetic disorder.

Causes of radiation damage

Sources of harmful radiation were previously limited to X-rays and natural radioactive materials such as uranium and plutonium. The radiation produced by X-rays used for diagnostic tests today has been significantly reduced than before. The most common sources of high-energy radiation are artificial radioactive materials used in therapeutics, research laboratories, industry, and nuclear reactors.

Nuclear power plants may occasionally leak large amounts of radiation, such as the Three Mile Island Nuclear Power Plant in Pennsylvania in 1979 and the Chernobyl Nuclear Power Plant accident in Ukraine in 1986. The Sanli Island accident did not cause a lot of radiation; in fact, people living within 1 mile of the plant received less radiation than the average person received X-ray radiation in a year. Those living near the Chernobyl power plant suffered much greater radiation, killing more than 30 people and injuring many. Radiation from the accident has spread to Europe, Asia and the United States.

In the first 40 years of using nuclear energy, there were a total of 35 severe radioactive accidents (excluding the Chernobyl accident) and 10 deaths, but none were related to nuclear power plants. In the United States, nuclear power reactors must meet strict federal standards that limit the release of radioactive materials to a minimum.

Radiation injury related concepts

Rays can be measured in several different units. Roentgen (R) is a unit of measurement for the amount of radiation in the air. Gy (Gy) is a unit of measurement for the actual absorption of energy by a body tissue or substance that is irradiated. Some types of radiation produce more biological effects than others. Svd is the biological effect of absorbing the same amount of energy on the body.

Causes of Radiation Injury Effects and Degree of Damage

The degree of radiation damage is related to the dose, duration and rate of exposure. A beam of unidirectional high-speed radiation can be fatal, while radiation with the same total dose is accepted within weeks or months, and there may be only one effect that is barely measurable. The total dose and rate of irradiation determine the immediate effects of genetic material in the cell.

Dose rate is the ratio of the total dose of human radiation to time over a period of time. The radiation dose rate in the daily life environment is very low, about 1-2mGy (1mGy = 1 / 1000Gy) per year, and has no effect on the body. Radiation effects are cumulative; each exposure plus the previous cumulative dose determines the total dose, which is likely to have an impact on the body. As the dose rate or total dose increases, the perceived effect increases.

The area irradiated by the radiation also affects the effect. For example, when the radiation of more than 6 Gy radiates the entire body surface, it often causes death; however, if the irradiation area is small, such as radiation treatment of cancer, irradiation with a dose of 3 to 4 times will not cause serious damage to the body. The distribution of radiation in the body is also important. Sites where cells proliferate rapidly, such as the intestine and bone marrow, are more vulnerable to radiation damage than sites where they proliferate slowly, such as muscles and tendons. When treating cancer with radiation, protect the vulnerable parts of the body with a protective cover every time to avoid damage when using high doses of radiation.

Radiation injury symptoms of radiation injury

Radiation can cause two types of injury: acute injury (immediate effect) and chronic injury (delayed response). Acute radiation syndrome can damage many organs.

Radiation damage brain syndrome

Cerebral syndrome is caused by high doses (greater than 30 Gy) of radiation. Often life-threatening. The first symptoms are nausea and vomiting, followed by fatigue, lethargy, and even coma. These symptoms are much like encephalitis. Tremors, convulsions, and ataxia occur within a few hours until death.

Radiation Injury Gastrointestinal Syndrome

Gastrointestinal syndrome is caused by radiation that is smaller but still higher (above 4 Gy) than the above doses. Symptoms include severe nausea, vomiting, and diarrhea, leading to severe dehydration. Initially, the symptoms were caused by necrosis of the mucosal cells of the gastrointestinal tract. Symptoms recur due to progressive damage to the intestinal wall and bacterial infection. Finally, the cells that absorbed nutrients were completely destroyed, and a large amount of blood oozed from the injured site. New cells are usually regenerated 4 to 6 days after irradiation. But even then, the patient is likely to die of bone marrow failure after 2 to 3 weeks.

Radiation-induced hematopoietic syndrome

Hematopoietic system rays damage hematopoietic organs that produce blood cells such as bone marrow, spleen, and lymph nodes. Symptoms can occur after 2 to 10 Gy of radiation. At the beginning, there are loss of appetite, indifference, nausea, and vomiting. The symptoms are most severe 6 to 12 hours after radiation. Obviously, the symptoms can completely disappear after 24 to 36 hours. During relatively stable symptoms, hematopoietic cells in the lymph nodes, spleen, and bone marrow begin to decrease, causing severe shortages of red and white blood cells. Leukopenia that fights infection can cause serious infections.

- Radiation Damage Related Charts-Annual American Radiation Exposure

Annual average dose of radiation source (mSv)

Natural radiation source 0.82

Medical radiation (such as X-rays) 0.77

Weapon test radioactive dust 0.04 0.05

Nuclear industry <0.01

Nuclear research 0.01 or less

Consumer goods 0.03 0.04

Air transport 0.005

Radiotherapy Drug Transport 0.0001

Other 0.15

Total 1.84

If the total radiation dose exceeds 6 Gy, it is often life-threatening due to hematopoietic and gastrointestinal dysfunction.

Acute radiation sickness occurs after radiation treatment, especially after exposure to the abdomen of a patient. Symptoms include nausea, vomiting, diarrhea, loss of appetite, headache, fatigue, and tachycardia, which often disappear within hours or days. The cause is unknown.

Long-term or repeated exposure to low-dose radiation from radioactive implants or exogenous radiation can cause amenorrhea, decreased fertility in men and women, decreased sexual desire in women, cataracts, anemia, white blood cells and thrombocytopenia. Partial body exposure to large doses of radiation can cause hair loss, skin atrophy, ulcers, keratosis, spider nevus (telangiectasia). Can eventually cause skin squamous cell carcinoma. Ingestion of radioactive compounds, such as radium salts, can cause bone tumors years later.

Occasionally long after radiation treatment of cancer, severe damage to the irradiated organ may occur. Delayed impairment of renal function is unlikely to occur 6 months to 1 year after receiving high-dose radiation; anemia and hypertension may also occur. The accumulation of large doses of muscle can cause painful myopathy, with muscle atrophy and calcification, and very few patients can cause malignant muscle tumors. Radiation therapy for lung cancer can cause radiation pneumonitis. Large doses of radiation can also cause severe fibrosis of the lung tissue, which is life-threatening. After extensive mediastinal irradiation, it can cause myocarditis and pericarditis. Cumulative spinal cord exposure can cause catastrophic damage and paralysis. Extensive abdominal exposure (such as lymph node, testicular, or ovarian cancer) can cause chronic intestinal ulcers, fibrosis, and perforation.

During cell differentiation, radiation can alter genetic material. Cells outside the reproductive system, this change can cause abnormal cell proliferation, leading to diseases such as cancer and cataracts. Irradiation of ovaries and testes of experimental animals found that genetic abnormalities (mutations) of offspring increased, but this effect has not been confirmed in humans. Some researchers consider exposure below a certain dose (threshold) to be harmless. Other researchers believe that exposure to the ovaries and testes is harmful. As no conclusion has been reached so far, most authoritative sources recommend that both medical and professional exposure to radiation should be kept to a minimum. In any case, the probability of causing radiation-related diseases or genetic mutations per 1 Gy of radiation dose is estimated to be 1 in 100, and the average annual radiation dose per person is about 0.002 Gy.

Diagnosis and prognosis of radiation injury

A person who develops symptoms after receiving radiation treatment or being exposed to radiation in an accident should suspect radiation damage. There are many ways to check the body dysfunction, but there is no special method to diagnose radiation damage. The prognosis depends on the total dose, dose rate, and distribution in the body. Repeated blood and bone marrow examinations will reveal the severity of the injury.

In the presence of cerebral syndrome or gastrointestinal syndrome, the diagnosis is clear, but the prognosis is poor. Cerebral syndrome occurs, often dying within hours to days; gastrointestinal syndrome often dies within 3 to 10 days, although some people can survive for several weeks; hematopoietic system syndrome often dies within 8 to 50 days; it may Death was caused by severe infection in 2 to 4 weeks or major bleeding in 3 to 6 weeks.

Chronic radiation damage may be caused by exposure to radiation without knowing or being ignored, and diagnosis is difficult or even impossible. If radiation damage is suspected, the possibility of occupational radiation should be sought, and information can be consulted at the agency that maintains the radiation record. For those who are obviously exposed to radiation and have abnormalities, the chromosomes containing genetic material in the cells can be regularly checked. However, the results of these tests do not necessarily lead to a positive conclusion. If exposed to radiation, check your eyes regularly for cataracts.

Radiation Injury Treatment

The skin contaminated with radioactive material should be immediately rinsed with a large amount of water, and if possible, it should be washed with a special cleaning solution. Small skin lacerations must be carefully rinsed and debrided to remove all radioactive particles. If radioactive material is swallowed shortly, try to induce vomiting immediately. If receiving excessive radiation, respiratory monitoring and radiological examination of urine should be performed.

Radiation injured acute brain syndrome

Acute brain syndrome is fatal and tends to palliative care; relieves pain, anxiety, and difficulty breathing. Use sedatives to control convulsions.

Radiation-induced acute radiation sickness caused by abdominal radiotherapy

For acute radiation sickness caused by abdominal radiation therapy, anti-nausea and vomiting drugs (antiemetics) can be taken before radiation therapy to reduce symptoms.

Radiation Injury Gastrointestinal Syndrome

Gastrointestinal syndrome can be relieved by antiemetics, sedatives and a less irritating diet. You can eat the juice. Repeated blood transfusions and the use of antibiotics help patients to survive the first 4 to 6 days of exposure to radiation, until new cells in the gastrointestinal tract begin to grow.

Radiation-induced hematopoietic syndrome

Hematopoietic system syndrome, to correct anemia with blood transfusion. With antibiotics, absolutely avoid contact with people with germs to prevent infection. Bone marrow transplantation is performed if necessary (see section 170), but the success rate of transplantation is lower except for patients with identical twin bone marrow.

The treatment of long-term effects of chronic radiation must first eliminate the influence of radiation sources. Some radioactive substances such as radium, krypton, and radioactive strontium can be eliminated from the body with drugs, and these substances are absorbed from the urine and excreted from the urine. However, these drugs work best only after exposure to radiation. Radiation ulcers and tumors should be repaired by surgery and plastic surgery. Radiation-induced leukemia is treated in the same way as other leukemias, with chemotherapy (see section 157). Correcting anemia through blood transfusion is a temporary measure, as radiation-damaged bone marrow is unlikely to regenerate. Infertility cannot be cured, but hormone replacement therapy can be used for low levels of sex hormones caused by ovarian and testicular dysfunction.