Acute Exposure

An exposure to radiation that occurred in a matter of minutes rather than in longer, continuing exposure over a period of time.


As low as is reasonably achievable: According to the NRC Regulations Title 10, Code of Federal Regulations, ALARA means making every reasonable effort to maintain exposures to radiation as far below the dose limits in this part as is practical consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of nuclear energy and licensed materials in the public interest.

Alpha Particle

The nucleus of a helium atom, made up of two neutrons and two protons with a charge of +2. Certain radioactive nuclei emit alpha particles. Alpha particles generally carry more energy than gamma or beta particles, and deposit that energy very quickly while passing through tissue. Alpha particles can be stopped by a thin layer of light material, such as a sheet of paper, and cannot penetrate the outer, dead layer of skin. Therefore, they do not damage living tissue when outside the body. When alpha-emitting atoms are inhaled or swallowed, however, they are especially damaging because they transfer relatively large amounts of ionizing energy to living cells.

Background Radiation

Radiation from cosmic sources; naturally occurring radioactive materials, including radon (except as a decay product of source or special nuclear material), and global fallout as it exists in the environment from the testing of nuclear explosive devices. It does not include radiation from source, byproduct, or special nuclear materials regulated by the Nuclear Regulatory Commission. The typically quoted average individual exposure from background radiation is 360 millirems per year.

Beta Particle

Electrons ejected from the nucleus of a decaying atom. Although they can be stopped by a thin sheet of aluminum, beta particles can penetrate the dead skin layer, potentially causing burns. They can pose a serious direct or external radiation threat and can be lethal depending on the amount received. They also pose a serious internal radiation threat if beta-emitting atoms are ingested or inhaled.


A thin, flexible wires inserted into a vein, typically in the groin or neck. Used in procedures such as catheter ablation.

Cobalt (Co)

Gray, hard, magnetic, and somewhat malleable metal. Cobalt is relatively rare and generally obtained as a byproduct of other metals, such as copper. Its most common radioisotope, cobalt-60 (Co-60), is used in radiography and medical applications. Cobalt-60 emits beta particles and gamma rays during radioactive decay.

Declared Pregnant Woman

A woman who is also a radiation worker and has voluntarily informed her employer, in writing, of her pregnancy and the estimated date of conception.


A small portable instrument (such as a film badge, thermoluminescent dosimeter [TLD], or pocket dosimeter) for measuring and recording the total accumulated dose of ionizing radiation a person receives.


The theory and application of the principles and techniques involved in measuring and recording doses of ionizing radiation.


For purposes of external exposure, hand, elbow, arm below the elbow, foot, knee, leg below the knee.

Fetal Badge

Dosimeter supplied to a declared pregnant radiation worker to monitor radiation dose to the fetus for the term of the pregnancy.

Gamma Rays

High-energy electromagnetic radiation emitted by certain radionuclides when their nuclei transition from a higher to a lower energy state. These rays have high energy and a short wave length. All gamma rays emitted from a given isotope have the same energy, a characteristic that enables scientists to identify which gamma emitters are present in a sample. Gamma rays penetrate tissue farther than do beta or alpha particles, but leave a lower concentration of ions in their path to potentially cause cell damage. Gamma rays are very similar to x-rays.

Ionizing Radiation

Radiation composed of particles that individually carry enough kinetic energy to liberate an electron from an atom or molecule, ionizing it. Ionizing radiation is generated through nuclear reactions, either artificial or natural, by very high temperature (e.g. plasma discharge or the corona of the Sun), via production of high energy particles in particle accelerators, or due to acceleration of charged particles by the electromagnetic fields produced by natural processes, from lightning to supernova explosions.

Millirem (mrem)

A millirem (mrem) is one thousandth of a rem. Millirem (mrem) is often used for the dosages commonly experienced, such as the amount of radiation received from medical x-rays and background sources.

Needlestick Injury

The penetration of skin by a needle or other sharp object, which was in contact with blood, tissue, or other body fluid before the exposure. Occupational needlestick injuries primarily affect healthcare workers. Various other occupations are also at increased risk of needlestick injury, including law enforcement, laborers, tattoo artists, food preparers, and agricultural workers.

Non-Ionizing Radiation

Radiation that does not produce ionization in biological tissue. Examples are ultraviolet radiation, light, infrared radiation and radiofrequency radiation.


The National Institute of Standards and Technology (NIST) administers the National Voluntary Laboratory Accreditation Program (NVLAP). NVLAP provides accreditation services through various laboratory accreditation programs (LAPs), which are established on the basis of requests and demonstrated need. Each LAP includes specific test or calibration standards and related methods and protocols assembled to satisfy the unique needs for accreditation in a field of testing or calibration. NVLAP accredits public and private laboratories based on evaluation of their technical qualifications and competence to carry out specific calibrations or tests.

Accreditation requirements are established in accordance with the U.S. Code of Federal Regulations (CFR, Title 15, Part 285), NVLAP Procedures and General Requirements, and encompass the requirements of ISO/IEC 17025. Accreditation is granted following successful completion of a process which includes submission of an application and payment of fees by the laboratory, an on-site assessment, resolution of any nonconformities identified during the on-site assessment, participation in proficiency testing, and technical evaluation. The accreditation is formalized through issuance of a Certificate of Accreditation and Scope of Accreditation and publicized by announcement in various government and private media.

NVLAP provides an unbiased third-party evaluation and recognition of performance. NVLAP accreditation signifies that a laboratory has demonstrated that it operates in accordance with NVLAP management and technical requirements pertaining to quality systems; personnel; accommodation and environment; test and calibration methods; equipment; measurement tractability; sampling; handling of test and calibration items; and test and calibration reports. NVLAP accreditation does not imply any guarantee (certification) of laboratory performance or test/calibration data; it is solely a finding of laboratory competence.

Occupational Dose

The internal and external dose of ionizing radiation received by workers in the course of employment. Occupational dose does not include the dose from natural background, medical or dental diagnosis or medical therapy.

Radioisotope (Radioactive Isotope)

Isotopes of an element that have an unstable nucleus. Radioactive isotopes are commonly used in science, industry, and medicine. The nucleus eventually reaches a stable number of protons and neutrons through one or more radioactive decays. Approximately 3,700 natural and artificial radioisotopes have been identified.


A unit used to measure the amount of radiation that results in the same amount of human tissue damage caused by one roentgen of radiation.


A small and extremely sharp bladed instrument used for surgery, or anatomical dissection. Medical scalpels are all single-use disposable. Disposable scalpels usually have a plastic handle and are used once, then the entire instrument is discarded. Scalpel blades are usually individually packed in sterile pouches but are also offered non-sterile. Scalpel blades are usually made of hardened and tempered steel, stainless steel, or high carbon steel.

Spare Badge

An extra badge sent at customer request for assignment to:
– Visitors
– New employees
– Employees who have lost their normal dosimeter

Thermoluminescent Dosimeter (TLD)

A type of radiation dosimeter. A TLD measures ionizing radiation exposure by measuring the amount of visible light emitted from a crystal in the detector when the crystal is heated. The amount of light emitted is dependent upon the radiation exposure.

Whole Body

For purposes of external exposure, head, trunk, arms above the elbow or legs above the knee.


Electromagnetic radiation caused by deflection of electrons from their original paths, or inner orbital electrons that change their orbital levels around the atomic nucleus. X-rays, like gamma rays can travel long distances through air and most other materials. Like gamma rays, x-rays require more shielding to reduce their intensity than do beta or alpha particles. X-rays and gamma rays differ primarily in their origin: x-rays originate in the electronic shell; gamma rays originate in the nucleus.

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