Vocabulary Flashcards
Ionizing Radiation
Radiation that possesses the ability to remove electrons from atoms by a process called ionization
Somatic Effects
Effects of radiation on the body being irradiated
Genetic Effects
Effects of radiation on the genetic code of a germ cell; Affects the next generation
Artificially produced radiation
Man-made radiation (e.g., medical x-rays)
Primary Radiation
Radiation exciting the x-ray tube
Exit Radiation
X-rays that emerge from the patient and strike the image receptor, AKA Remnant radiation; image producing radiation
Attenuation
Absorption and scatter (loss of intensity) of the x-ray beam as it passes through the patient
Heterogeneous beam
x-ray beam that contains photons of many different energies
Photoelectric effect
Absorption of x-ray photons in the atoms of the body
Compton Effect
Scatter of x-ray photons in the atoms of the body
Roentgen (R)
Traditional unit of in-air exposure
Coulombs per Kilogram (C/kg)
SI unit of in-air exposure
Rad
Traditional unit of absorbed dose
Gray
SI unity of absorbed dose
Rem
Traditional unit of equivalent dose and effective dose
Sievert
SI unit of equivalent dose and effective dose
Curie
Traditional unit of activity
Becquerel
SI unit of activity
National Academy of Sciences/National Research Council Committee on the Biological Effects of Ionizing Radiation (NAS/NRC-BEIR)
Organization that studies biologic effects of ionizing radiation and publishes resulting data
International Commission on Radiological Protection (ICRP)
Organization that publishes international radiation protection guideline
National Council on Radiation Protection and Measurements (NCRP)
Organization that publishes radiation protection guidelines for the US
Nuclear Regulatory Commission (NRC)
Organization that enforces radiation protection standards at the federal level related to the use of radioactive material
Effective dose limit
Upper boundary dose that can be absorbed, either in a single exposure or annually, with a negligible risk of somatic or genetic damage to the individual; Effective dose implies whole-body radiation exposure
Cumulative effective dose (CED)
Lifetime occupational exposure must not exceed the radiographer’s age multiplied by 1 rem
Equivalent dose limit
Upper boundary dose that can be absorbed, either in a single exposure or annually, with a negligible risk of a deterministic effect
As low as reasonably achievable (ALARA)
Concept of radiologic practice that encourages a radiation users to adopt measures that keep the dose to the patient and themselves at minimal levels
Dose-Response curves
Graphs that illustrate the relationship between radiation dose and the response of the organism to exposure; may be linear or nonlinear, threshold or nonthreshold
Probabilistic Effects
Randomly occurring effects of radiation; the probability of such effects is proportional to the dose (increased dose equals increased probability not severity, of effects)
Deterministic Effects
Effects of radiation that becomes more severe at high levels of radiation exposure and do not occur below a certain threshold dose
Genetically significant dose (GSD)
Average annual gonadal dose of radiation to individuals of childbearing age; addresses the relationship of gonadal doses to individuals vs. an entire population and the overall effects
Linear Energy Transfer (LET)
Amount of energy deposited by radiation per unit length of tissue
Relative biologic effectiveness (RBE)
Ability to produce biological damage; varies with the LET
Direct effect
Effect that occurs when radiation directly strikes DNA in the cellular nucleus
Indirect effect
Effect that occurs when radiation strikes the water molecules in the cytoplasm of the cell
Radiolysis of water
Effect that occurs as radiation energy is deposited in the water of the cell; The result of radiolysis is an ion pair in the cell: a positively charged water molecule (HOH+) and a free electron
Mutation
Erroneous information passed to subsequent generations via cell division
Law of Bergonie and Tribondeau
Cells are most sensitive to radiation when they are immature, undifferentiated, and rapidly dividing
Early somatic effects of radiation
Hematopoietic syndrome; GI syndrome; central nervous system syndrome
Late somatic effects of radiation
Carcinogenesis; Cataractogenesis; embryologic effects; thyroid disfunction; life span shortening
Cardinal principles of radiation
Time, distance, and shielding
Distance
Best protection against radiation exposure
Personnel monitoring devices examples
Optically stimulated luminescence (OSL) badge, film badge, thermoluminescent dosimeter (TLD)
Mean marrow dose
Average dose of radiation to the bone marrow
