Radiation injuries

High doses of ionizing radiation can cause acute illness by reducing blood cell production and damaging the digestive tract.

A very high dose of ionizing radiation can also damage the heart and blood vessels (cardiovascular system), the brain and the skin.

A radiation injury resulting from high to very high doses is called a tissue reaction. The dose required to cause visible tissue damage varies by tissue type.

Ionizing radiation can increase the risk of cancer.

Exposure of sperm and eggs to radiation increases the risk of genetic defects in offspring.

Physicians remove external and internal (inhaled or ingested) radioactive material as much as possible and treat the symptoms and complications of radiation injury.

In general, ionizing radiation refers to high-energy electromagnetic waves (X-rays and gamma rays) and particles (alpha particles, beta particles and neutrons) that can release electrons from atoms (ionization). Ionization alters the chemistry of the atoms involved and of all molecules containing these atoms. By altering the molecules in the strictly ordered environment of the cell, ionizing radiation can rupture and damage cells. Depending on the level of dose, the organs irradiated, and the type of cell damage, ionizing radiation can cause acute illness, increase the risk of cancer, or both.

Ionizing radiation is caused by radioactive substances (radionuclides) such as uranium, radon and plutonium. It is also generated by equipment, such as X-ray machines and the equipment used for radiation therapy.

Radio waves, such as those from cell phones and AM and FM radio stations, and visible light are also forms of electromagnetic radiation. However, because of their low energy, these types of radiation do not ionize and are not harmful to cells at the levels to which they are usually exposed. In this description, "radiation" refers exclusively to ionizing radiation.

Radiation measurement

The intensity of radiation is measured in several different units. The x-ray (R) is a measure of the ionizing power of radiation in the air and is usually used to express the intensity of irradiation. How much radiation someone is exposed to and how much radiation has been absorbed into the body can vary widely. The Gray value (Gy) and Sievert value (Sv) are measures of radiation dose, d. h. the sum of radiation deposited in matter. These units are used to measure dose in humans after exposure to radiation. The Gy and the Sv are similar, except that the Sv also measures how effective the different types of radiation are at causing damage, and how sensitive the different tissues of the body are to radiation. Low-level radiation is measured in milligrays (mGy; 1 mGy = 1 /1000 Gy) and millisieverts (mSv; 1 mSv = 1 /1000 Sv).

Contamination vs. Radiation

There are two ways in which a person’s radiation exposure can increase: through contamination and through exposure to radiation. Radiation. In many of the most serious radiation accidents, victims were exposed to both.

Contamination Is contact with radioactive material and its retention, typically in the form of dust or liquid. External contamination involves the skin or clothing, some of which may fall off or be rubbed off, contaminating other people and objects. Internal contamination is radioactive material deposited in the body through ingestion, inhalation, or skin tears. Once in the body, radioactive material can travel to various sites, such as the bone marrow, where it continues to emit radiation, increasing the dose until it is removed or has released all its energy (decays). Internal contamination is more difficult to correct than external contamination.

A contamination or. Radiation consists of being exposed to radiation but not radioactive material, which means that contamination does not occur. A common example is diagnostic X-rays, which are used to evaluate a broken bone, for example. One can be exposed to radiation without there being direct contact between the person and the source of radiation (such as radioactive material or an x-ray machine). When the source of radiation is removed or switched off, the exposure ceases. Radiation to. People who are irradiated but not contaminated are not radioactive, d. h., That they do not give off radiation and that their dose from that radiation source does not continue to increase.

Did you know .

On average, a person in the United States is exposed to about the same dose of natural radiation as that from human-generated radiation sources (almost all of which are medical radiation sources used to diagnose or treat a disease).

Sources of radiation

Everyone is constantly exposed to low-level radiation that occurs in nature (background radiation), and from time to time to radiation from man-made sources. Natural background radiation varies enormously worldwide and within countries. In the U.S., people are exposed to an average of about 3 mSv/year from natural sources, with levels varying roughly from 0.5 to 20 mSv per year depending on region, elevation above sea level, and local geology. An additional 3 mSv/year comes from artificial sources (mostly medical), so the average actual total dose per capita per year is about 6 mSv.

Background radiation

Sources of background radiation include:

Solar radiation and cosmic rays

Naturally occurring radioactive elements in the earth

Cosmic and solar radiation are strongly blocked by the Earth’s atmosphere, but are concentrated at the north and south poles because of the Earth’s magnetic field. Therefore, the impact of cosmic radiation is greater for people living closer to the poles or at high altitudes, and during flight.

Radioactive elements, especially uranium and the radioactive products into which it naturally decays (such as radon gas), are present in many rocks and minerals. These elements eventually end up in various substances, including food, water and building materials. Radon exposure accounts for about two-thirds of the naturally occurring radiation exposure to which people are exposed.

Doses from natural background radiation, even taken together, are far too low to cause radiation injury. To date, there is no evidence of health effects attributable to differences in the level of naturally occurring background radiation, since its risks are either nonexistent or so small that no effects are observed, given the low doses involved.

Artificial radiation

The most common are the artificial or. Man-made radiation sources in medical imaging examinations that use X-rays (especially computed tomography Computed tomography (CT) In computed tomography (CT), formerly also called axial computed tomography (CAT), an X-ray source and an X-ray detector rotate around a patient. The X-ray detector. Learn more [CT]) or in procedures in which a radioactive substance is administered (nuclear medicine cardiac scans radionuclide scanning Radionuclide scanning involves the use of radionuclides to produce images. A radionuclide is the radioactive form of an element, i.e., an unstable atom, that is formed by the release of. Learn more ). People who receive radiation as part of cancer therapy can receive very high doses of radiation. However, many efforts are made to limit radiation to only the diseased tissues and to minimize radiation to normal tissues.

Exposures can also occur from other man-made sources, such as radiation accidents or atomic dust from nuclear weapons testing. However, these radiations are only a small part of the annual radiation exposure. Radiation accidents usually involve people who handle radioactive materials and X-ray sources, such as food irradiators, industrial X-ray machines, and medical X-ray machines. Such individuals may be exposed to significant doses of radiation. These accidents are rare and are usually the result of a violation of safety regulations. Radiation exposures have also been caused by lost or stolen medical or industrial sources containing high amounts of radioactive material. Radiation injuries have also occurred in patients who have been X-rayed or who have had certain medical procedures in which a pulsed X-ray beam is used to display a moving X-ray image on a screen (fluoroscopy). Of these injuries, some are due to accidents or improper use. Sometimes, however, unavoidable radiation-related complications and tissue reactions can occur even when such procedures are performed properly.

In rare cases, significant amounts of radioactive material have been released from nuclear power plants. Past examples include the Three Mile Island nuclear accidents in Pennsylvania in 1979, the Chernobyl nuclear accident in Ukraine in 1986, and the Fukushima Daiichi nuclear plant accident in Japan in 2011. The accident at Three Mile Island did not result in significant radiation exposures. In fact, people living within 1.6 km of the power plant were exposed to only about 0.08 mSv of additional radiation. The approximately 115.000 people evacuated from the area near the Chernobyl nuclear power plant, on the other hand, were exposed to an average dose of about 30 mSv. For comparison, the typical dose from a single CT scan is between 4 and 8 mSv. Exposure of workers at the Chernobyl power plant was even significantly higher. More than 30 workers and emergency responders died within a few months of the accident, and many more people contracted acute radiation illnesses. There has been low-dose contamination from Chernobyl as far away as Europe, Asia, and even the United States (to a lesser extent). The average cumulative radiation dose to the population in the low-level contaminated areas (various regions in Belarus, Russia, and Ukraine) over a 20-year period after the accident was estimated to be about 9 mSv. It should be noted that the average annual supplemental dose (0.5 to 1.5 mSv per year) to which residents in areas contaminated by radioactive fallout from Chernobyl were exposed is, on balance, lower than normal background radiation in the United States (3 mSv per year). Some workers at the Fukushima Daiichi power plant were exposed to significant doses of radiation, but there were no deaths or permanent radiation-induced tissue reactions. People living within a 20-kilometer radius of the Fukushima Daiichi power plant have been evacuated for safety reasons. However, it is estimated that none of the nearby residents was exposed to more than about 5 mSv of radiation. According to World Health Organization projections, there will be only a very small number of cancer-related deaths associated with this accident.

Nuclear weapons release a large amount of energy and radiation. These weapons have not been used against people since 1945. However, several countries now have nuclear weapons, and terrorist groups have also attempted to obtain them or build them themselves, increasing the risk that these weapons will be used again. The vast majority of nuclear weapon detonation accidents are caused by the blast and thermal burns. A smaller part of the diseases (but still a considerable one) is caused by radiation.

Regarding possible intentional radiation due to terrorist activities (see Nuclear Weapons Radiation Exposure is discussed in detail elsewhere. Mass casualties with radiation exposure can be caused by the explosion of a nuclear device. A nuclear. Learn More ) include the use of a device that contaminates an area by spraying radioactive material (a radiation dispersal device that uses conventional explosive devices is called a "dirty bomb"). Other possible terrorist scenarios would include the use of hidden radiation sources that expose unsuspecting people to high doses of radiation, an attack on a nuclear power plant or radioactive material storage facility, and the detonation of nuclear weapons.

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