59 Radioactive Materials Safety Manual Bioassay – the determination of kinds, quantities or concentrations, and, in some cases, the locations of radioactive material in the human body, whether by direct measurement (in vivo counting) or by analysis and evaluation of materials excreted or removed from the human body. Body Burden – the amount of radioactive material which if deposited in the total body will produce the maximum permissible dose rate to the critical organ. Bremsstrahlung – electromagnetic (X-ray) radiation produced by the deposition of charged particles in matter. Usually associated with energetic beta emitters, such as 32Phosphorus. Calibration – determination of variation from standard, or accuracy, of a measuring instrument to ascertain necessary correction factors. Charged Particle – an ion. An elementary particle carrying a positive or negative electric charge. Chronic Exposure – the absorption of radiation (or intake of radioactive materials over a long period of time), i.e., over a lifetime. Committed Dose Equivalent – the dose equivalent to organs or tissues of reference that will be received from an intake of radioactive material by an individual during the 50-year period following the intake. Committed Effective Dose Equivalent – the sum of the products of the weighting factors applicable to each of the body organs or tissues that are irradiated and the committed dose equivalent to these organs or tissues. Contamination, Radioactive – deposition of radioactive material in any place where it is not desired, and particularly in any place where its presence may be harmful. The harm caused may be a source of excessive exposure to personnel or the validity of an experiment or a procedure. Controlled Area – an area, outside of a restricted area but inside the site boundary, access to which can be limited by the licensee for any reason. Count – the external indication of a device designed to enumerate ionizing events. It may refer to a single detected event or to the total registered in a given period of time. The term is often erroneously used to designate a disintegration, ionizing event, or voltage pulse. Critical Organ – the organ or tissue, the irradiation of which will result in the greatest hazard to the health of the individual or his descendants. Curie – the quantity of any radioactive material in which the number of disintegrations is 3.7 x 1010 per second. Abbreviated Ci. Decay, Radioactive – disintegration of the nucleus of an unstable nuclide by the spontaneous emission of charged particles and/or photons. Decontamination – the reduction or removal of contaminating radioactive material from a structure, area, object, or person. Decontamination may be accomplished by (1) treating the surface to remove or decrease the contamination, (2) letting the material stand so that the radioactivity is decreased as a result of natural decay, and (3) covering the contamination to shield or attenuate the radiation emitted. Deep Dose Equivalent – applies to external whole-body exposure and is the dose equivalent at a tissue depth of one centimeter (1000 mg/cm2 ). Deterministic Effect - is an effect which has a threshold dose and the severity of the observed effect increases with dose. Dose or Radiation Dose – a generic term that means absorbed dose, dose equivalent, effective dose equivalent, committed dose equivalent, committed effective dose equivalent, or total effective dose equivalent, as defined in other paragraphs of this section. Dose Rate – the radiation dose delivered per unit of time. Measured, for example, in rem per hour.