What is Radiation Protection?
Sources of Radiation Exposures
Radiation exposure can be classified as occupational, non-occupational (naturally occurring), and man-made sources. This radiation safety and protection resource will be focused on occupational exposure, primarily
What is Radiation Protection?
Sources of Radiation Exposures
Radiation exposure can be classified as occupational, non-occupational (naturally occurring), and man-made sources. This radiation safety and protection resource will be focused on occupational exposure, primarily in the field of medicine, although medical radiation is classified under man-made sources.
Biological Effects of Radiation
There are two broad categories of health effects, stochastic and non-stochastic, related to radiation exposure. The severity or type of health effect is dependent on the duration and amount of radiation exposure. Stochastic refers to the probability of something happening. Consequently, stochastic effects are associated with long-term, low-level (chronic) exposure to radiation. When radiation exposure levels increase, the probability of health effects are more likely to occur, but the type or severity is not influenced by the effect. “Cancer is considered by most people the primary health effect from radiation exposure.”
Non-stochastic effects occur when an individual is exposed to high levels of radiation. The severity of the health effects increase as exposure increases. Acute exposure is when an individual receives a high-level of exposure in a short period of time. Unlike stochastic effects, acute exposure frequently results in non-cancerous health effects such as radiation burns, radiation sickness, premature aging, and even death. Medical patients who receive radiation treatments often experience some of these health effects.
Radiation Protection Basics
There are three basic concepts that apply to all types of ionizing radiation. Time, distance, and shielding are the basis of radiation protection principles.
There is a direct correlation with the amount of radiation exposure received and the amount of time individuals spend near the radiation source. There are two types of exposures, internal exposure and external (direct) exposure, the focus of our attention will be on minimizing external exposure. Exposure time is the length of time and individual is exposed to the source of radiation. Minimizing the time for external (direct) exposure from gamma and x-rays directly reduces radiation dose.
The greater the distance between the individual and the radiation source, the lower their exposure. By doubling the distance between your body and the radiation source will divide the radiation exposure by a factor of 4. Halving the distance, increases the exposure by a factor of four.
Shielding is any type of material that will absorb radiation between the individual and the source of radiation. The amount of energy emitted from the radiation source will determine what shielding material is required to effectively attenuate the radiation. The greater the shielding around a radiation source, the smaller the exposure.
For example, thick, dense shielding, such as lead, is required to protect against x-rays, while a thin piece of paper can effectively shield against alpha particles. By using absorber materials such as lead for X-rays, ionizing radiation exposures can be reduced. Shielding comes in many forms including:
- Walls, windows, control booths, and doors
- Mobile rigid shields
- Suspended transparent barriers
- Flexible (lead or lead equivalent) aprons, vests, and skirts
- Thyroid shields
- Lead gloves
- Leaded safety eye glasses (with and without side shields)
What is ALARA?
ALARA is an acronym for As Low As Reasonably Achievable. ALARA was introduced by the International Commission On Radiological Protection (ICRP) and is a radiation safety principles for minimizing radiation doses and releases of all radioactive materials by employing all reasonable methods. In addition to being a sound radiation safety principle, ALARA is also a regulatory requirement for all radiation safety programs. Time, distance, and shielding are three major principles used to minimize radiation exposure and maintaing doses as low as reasonably achievable.
Occupational Dose Limits
Occupational dose limits provide guidelines for radiation workers by establishing a maximum annual occupational dose limit. “These maximum dose limits are promulgated on the basis that when applied to occupationally exposed radiation workers they will result in a level of risk no greater than that in other occupations which are deemed to have high safety standards.” By following the ALARA concept, operational dose limits are more stringent than the maximum legal dose. Maintaining doses ALARA provide radiation workers with an enhanced safety factor by working below the legal dose limits.
|Maximum Annual Occupational Dose|
|Whole Body||5000 millirem|
|Lens of the Eye||15000 millirem|
|Individuals in the General Public||100 millirem|
Shielding From Radiation
Whenever possible, appropriate shielding should be used to provide attenuation of the radiation being delivered to the healthcare personnel who are potentially exposed. Healthcare personnel must keep all all body parts out of the direct x-ray beam. There are a variety of shielding options available and may include, but are not limited to lead or x-ray aprons, lead glasses, lead gloves, thyroid collars, and lead shields.
During diagnostic imaging and interventional procedures involving radi