Radiation Protection Activity
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Ionizing radiation is all around us and we cannot avoid exposure to naturally occurring (background) forms of ionizing radiation. Controlled radiation sources, like those used in the irradiation process, tritium exit signs, or ionizing smoke detectors, can even protect us. We also benefit from radiation that is used in medicine, nuclear power generation, construction, and other industrial processes. People who work with radiation sources must follow radiation protection practices.
The public should also be aware of radiation protection principles and where they can be used to limit exposure to radiation. The three basic radiation protection concepts are time, distance and shielding.
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When radioactive atoms decay, they give off energy in the form of ionizing radiation (alpha particles, beta particles or gamma rays). The energy is called ionizing radiation because as this radiation moves through matter it has enough energy to knock tightly bound electrons from atoms. This causes the atom to become a charged ion. Radioactive atoms continue to decay (some for seconds or days, others for thousands of years) until they give off enough energy to become stable atoms and no longer emit ionizing radiation.
If ionizing radiation is absorbed by the body, the effects can potentially damage living cells and the DNA of these cells. Our bodies can handle some degree of exposure to ionizing radiation and still repair damaged cells. This is because humans have evolved in the presence of radiation. The effects of ionizing radiation may vary from person to person based on the total amount of energy absorbed, the time period and dose rate of the exposure, and the particular organs exposed. Dose refers to the quantity of energy absorbed by a person exposed to radiation and in the United States it is measured in millirem (mrem) or rem (Roentgen Equivalent Man). A person's risk generally increases with the amount of exposure.
People may be exposed to an increased radiation dose in certain situations (for example, when receiving a medical radiation treatment or during a radiological emergency). The concepts of time, distance and shielding are used to help limit radiation exposure. These radiation protection concepts can be applied separately or in combination. For example, people who work with radioactive materials may have time limits on how long they can be near a source which are set according to the exposure risk and shielding requirements such as wearing protective clothing or working behind a barrier.
Time: The dose of radiation you receive depends on how long you are near a radiation source. Setting time limits helps keep the time spent near a source of radiation as short as possible. For example, a worker may only be allowed to work around radioactive materials for 4 to 6 hours of an 8-hour shift.
Distance: The radiation dose you receive strongly depends on how close you are to a radioactive source. For example, barrels of radioactive waste might emit or give off a dose of 20 millirem (mrem) per hour at a distance of 1 foot from the surface. At 5 feet away, the dose rate would be less than 1 mrem per hour. As you distance yourself from the radiation source, you increase the likelihood that some radiation will lose its energy. As a rule, as you double the distance from the radiation source, you reduce the exposure by a factor of four. Conversely, decreasing the distance by half increases the exposure by a factor of four.
Shielding: Placing some material or a barrier, called shielding, between a person and a radiation source is another way to minimize the amount of radiation exposure. The image below shows the penetrating power of ionizing radiation (far right) and potential methods of shielding against alpha particles, beta particles, gamma rays and x-rays (center).
The international symbol of radiation, called a 'tri-foil,' or 'trefoil,' is used to identify areas restricted because of the presence of radiation. This symbol is displayed where radioactive materials are handled or where radiation-producing equipment is used. The trefoil symbol is often displayed with a message about the nature of the radiation hazard so authorized people can take the appropriate radiation protection precautions before entering the restricted area.
Believing the trefoil symbol was not intuitive, the United Nations introduced a new international radiation symbol in . Both symbols are meant to identify an ionizing radiation source and alert people of the potential dangers, so they can take action to protect themselves against radiation exposure. The new international symbol indicates to the public the importance of moving away from the source.
The hazardous materials, or HAZMAT, placard for radioactive materials must be displayed on packages, cargo units and transport vehicles when radioactive materials are transported by road, air, rail or water. Carriers are responsible for handling and storing these materials properly to prevent the release of radioactive materials. If an accident should occur during transport, the radioactive placard identifies the radiation source. First Responders can use this information to assess and respond to the situation appropriately.
Individuals and communities began thinking about fallout shelters in the late s and early s. In the early s fallout shelters became part of a comprehensive Defense Civil Preparedness Agency (DCPA) program created to prepare U.S. citizens in the event of a nuclear attack. The fallout shelter sign is displayed on the outside of some buildings (e.g., schools or other public buildings) so the public can locate them in the event of an emergency. The symbol may also be displayed inside buildings to mark access routes to the shelter area.
In , the Federal Emergency Management Agency (FEMA) took over the DCPA responsibilities. FEMA is still involved in disaster and emergency response along with state and local governments and other federal agencies, including the Environmental Protection Agency (EPA).
The Radiation Protection activities introduce middle and high school students to the history of radiation protection, the concepts and devices used in radiation protection, careers and laws related to radiation protection, and radiological emergency planning and response. Students will learn about events that led to the development of radiation protection practices. They will gain an understanding of the radiation protection concepts of time, distance and shielding and an understanding of the devices people can use to detect radiatio. Students will become familiar with the warning signs that may alert us and others to the presence of radiation.
NOTE: The term 'radiation' used in the activities generally refers to ionizing radiation unless otherwise indicated.
If you want to learn more, please visit our website Radiation Protection Solutions.
All EPA RadTown classroom materials can be used individually or modified and combined to create multiple lessons. Activity options allow you to customize the activities to fit the time you have available (e.g., 1'2 class periods) and meet the needs and interests of your students. The time needed to complete activities is between 45-60 minutes, not including optional activities or extensions.
The concepts within these activity sets can be used to support the following science standards:
The concepts in the Vocabulary Activities align with the following:
The concepts in the History of Radiation Protection activity align with the following:
The concepts in the Time, Distance and Shielding activity align with the following:
The concepts in the Radiation Warning and Protection Equipment activity align with the following:
The concepts in Buildings as Shielding activity align with the following:
The concepts in A Career in Radiation Protection activity align with the following:
The concepts in the Impact of Radiological Emergencies activity align with the following:
The concepts in the Benefits of Radiation activity align with the following:
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/4.0/ ), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Pain physicians usually use C-arm fluoroscopy for the treatment of patients. The C-arm fluoroscope is an important device for pain interventions. However, pain physicians can be exposed to radiation during use of C-arm fluoroscopy. According to a previous study in Korea, most pain physicians were worried about the adverse biological effects of radiation exposure [ 1 ]. However not many pain physicians had knowledge of radiation safety [ 1 , 2 ]. Furthermore, not many pain physicians used radiation protective devices and radiation protective methods [ 1 , 2 ]. Even though almost all pain physicians had used thyroid protectors and aprons, the use of lead glasses and gloves was low. For reducing radiation exposure, there are 3 principals: time, distance, and shielding.
Radiation exposure can be accumulated over the time of exposure. In C-arm fluoroscopy guided interventions, the time spent checking the C-arm fluoroscopy is related to the radiation exposure. The longer the exposure time, the more radiation exposure to the pain physician. Therefore, it is important to reduce the usage time of C-arm fluoroscopy [ 2 , 3 ]. For reducing the usage time, the physician has to improve his skill in intervention and the radiographer has to check the X-ray at the correct location, and at the right moment without blurred image.
A greater distance from the radiation source can reduce radiation exposure. The amount of radiation exposure is not inversely proportional to the distance from the radiation source, but is inversely proportional to the square of the distance [ 2 , 4 ]. This means that double the distance from the radiation source can reduce the radiation exposure not to 1/2 but to 1/4. Therefore, maintaining a greater distance from the X-ray generator is a very effective method for radiation safety. In a previous study of radiographers, two steps behind the mobile support structure can decrease the exposure of the radiographer by about 80% [ 4 ]. In another study, being only 20 cm farther from the center of the X-ray field can decrease the radiation exposure by about 73% [ 5 ].
There are many shielding devices such as caps, lead glasses, thyroid protectors, aprons, radiation reducing gloves, and so on, for radiation safety during C-arm fluoroscopy-guided interventions. Even though the protective effect is enough for radiation safety, no use of the devices cannot protect the physician from radiation. In Korea, the use rate of the apron and thyroid protector by pain physicians is over 80% [1,2,6]. However, the use rate of lead glasses was about 40%, and the use rate of radiation reducing gloves was lower than 35% [1]. The radiation shielding devices are expensive, and the use of shielding devices can be uncomfortable. However, when a physician uses these devices, they can be protected from radiation exposure.
Reducing the time of radiation exposure, a greater distance from radiation sources, and the use of shielding devices for radiation protection are important. Even if pain physicians have to use these three principles, I want to emphasize the importance of distance from the radiation source, because the longer distance from the radiation source may be more effective than reducing time or the use of shielding devices. If a pain physician decreases the time of radiation exposure in half, his radiation exposure will be halved. If a pain physician uses radiation protective devices with double the lead equivalent thickness, his radiation exposure will also be halved. However, if a pain physician stands double the distance from a radiation source, his radiation exposure will reduce to 1/4. Physicians do not pay money for a longer distance from the radiation source. Therefore, all physicians can use the principle of greater distance easily.
Do you want to reduce your radiation exposure? Please remember the 3 principles; time, distance, and shielding.
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