AML Acute myeloid leukemia.
apoptosis Programmed cell death. The cell death is characterized by a distinctive fragmentation of DNA that is regulated by cellular functions.
artificial radioactivity Man-made radioactivity produced by fission, fusion, particle bombardment, or electromagnetic irradiation.
attributable risk (AR) The estimated rate of a disease (such as lung cancer) that could, in theory, be prevented if all exposures to a particular causative agent (such as radon) were eliminated.
AU Astronomical unit.
background radiation The radiation to which a member of the population is exposed from natural sources, composed of terrestrial radiation due to naturally occurring radionuclides in the soil and building material, cosmic radiation originating in outer space, and naturally occurring radionuclides in the human body.
baseline rate of cancer The annual cancer incidence observed in a population in the absence of the specific agent being studied; the baseline rate includes cancers from a number of other causes, such as smoking and occupational exposures to chemicals.
becquerel (Bq) SI unit of activity. 1 Bq = 1 s−1 = 2.7 × 10−11 Ci.
BEIR Biological Effects of Ionizing Radiation. Refers to the reports by the National Research Council’s Committee on Biological Effects of Ionizing Radiation and its successor committees. The most recent of these reports is BEIR VII, published in 2006.
beta particle An electron or positron emitted from a nucleus during radioactive decay.
bias Factors that influence the outcome of data collection, such as causing certain measurements to have a greater chance of being included than others.
Boltzmann transport equation Describes the trajectory and interactions of particles traversing a medium. So called because of its similarity to the expression obtained by Boltzmann in connection with the kinetic theory of gases.
BRYNTRN Computational model of baryon transport.
cancer A malignant tumor of potentially unlimited growth, capable of invading surrounding tissue or spreading to other parts of the body by metastasis.
carcinogen An agent that can cause cancer. Ionizing radiation is a physical carcinogen; there are also chemical and biological carcinogens; biological carcinogens may be extrinsic (e.g., viruses) or intrinsic (genetic defects).
carcinoma A malignant tumor (cancer) of epithelial origin.
case-control study An epidemiologic study in which people with disease and a similarly composed control group are compared in terms of exposures to a putative causative agent.
cell culture The growing of cells in vitro (in a glass or plastic container, or in suspension) in such a manner that the cells are no longer organized into tissues.

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