63 Radioactive Materials Safety Manual Protective Barriers – barriers of radiation absorbing material, such as lead, concrete, plaster, and plastic, that are used to reduce radiation exposure. Proton – an elementary nuclear particle with a positive electric charge located in the nucleus of an atom. Public Dose – the dose received by a member of the public from exposure to radiation and to radioactive material released by a licensee, or to another source of radiation either within a licensee‘s controlled area or in unrestricted areas. It does not include occupational dose or doses received from background radiation, as a patient frommedical practices, or from voluntary participation inmedical research programs. Quality Factor – a modifying factor that is used to derive dose equivalent from absorbed dose. It corrects for varying risk potential due to the type of radiation. Rad – the special unit of absorbed dose. One rad is equal to an absorbed dose of 100 ergs/gram. Radiation Area – an area, accessible to individuals, in which radiation levels could result in an individual receiving a dose equivalent in excess of 0.005 rem (0.05 mSv) in one hour at thirty centimeters from the radiation source or from any surface that the radiation penetrates. Radiography – the making of shadow images on photographic film by the action of ionizing radiation. Radioisotope – a nuclide with an unstable ratio of neutrons to protons placing the nucleus in a state of stress. In an attempt to reorganize to a more stable state, it may undergo various types of rearrangement that involve the release of radiation. Radiology – that branch of medicine dealing with the diagnostic and therapeutic applications of radiant energy, including X-rays and radionuclides. Radionuclide – a radioactive isotope of an element. Radiosensitivity – the relative susceptibility of cells, tissues, organs, organisms, or other substances to the injurious action of radiation. Radiotoxicity term referring to the potential of an radionuclide to cause damage to living tissue by absorption of energy from the disintegration of the radioactive material introduced into the body. Relative Biological Effectiveness – for a particular living organism or part of an organism, the ratio of the absorbed dose of a reference radiation that produces a specified biological effect to the absorbed dose of the radiation of interest that produces the same biological effect. Rem – the special unit of dose equivalent. The dose equivalent in rems is equal to the absorbed dose in rads multiplied by the quality factor. (1 rem = .01 sievert) Removable Contamination – contamination deposited on the surface of structures, areas, objects or personnel that can readily be picked up or wiped up by physical or mechanical means during the course of a survey or during decontamination efforts. Restricted Area – an area, access to which is limited by the licensee for the purpose of protecting individuals against undue risks from exposure to radiation and radioactive materials. Restricted area does not include areas used as residential quarters, but separate rooms in a residential building may be set apart as a restricted area. Roentgen (R) – the quantity of X-ray or gamma radiation such that the associated corpuscular emission per 0.001293 gram of dry air produces, in air, ions carrying one electrostatic unit of quantity of electricity of either sign. Amount of energy is equal to 2.58 x 10-4 coulombs/kg air. The Roentgen is a special unit of exposure. Scintillation Counter – a counter in which light flashes produced in a scintillator by ionizing radiation are converted into electrical pulses by a photomultiplier tube. Sealed Source – radioactive material that is permanently bonded or fixed in a capsule or matrix designed to prevent release and dispersal of the radioactive material under the most severe conditions which are likely to be encountered in normal use and handling.