Safety Registry Review Flashcards
Ionizing radiation
radiation that possess 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 cell; affects the next generation
Natural background radiation
radiation contained in the unpolluted environment
Artificially produced radiation
also called man-made radiation (e.g., medical x-rays)
Primary radiation
radiation exiting the tube
Exit radiation (remnant radiation; image producing radiation)
x-rays that emerge from the patient and strike the image receptor
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 from the atom of the body
Air kerma
unit of exposure
Gray
unit of absorbed dose, measured in joules per kilogram (j/kg); 1 Gy = 1 J/kg
Gray(a)
unit of radiation absorbed in air
Gray (t)
unit of radiation absorbed in tissue
Sievert
unit of effective dose
Sievert
unit of equivalent dose
Becquerel
unit of activity
National academy of sciences/national research council committee on the biological effects of ionizing radiation (NAS/NRC-BEIR)
organization that studies biological effects of ionizing radiation and publishes resulting data
International commission on radiologic protection
organization that publishes international radiation protection guidelines
National council on radiation protection and management (NCRP)
organization that publishes radiation protection guidelines for the United States
Nuclear regulatory commission (NRC)
organization that enforces radiation protection standards at the federal level related to use of radioactive material
NCRP Report #102
makes recommendations on equipment design and protection regarding lead shielding and fluoroscopic and mobile exposure rates
NCRP Report #116
defines annual exposure limits; makes recommendations pertaining to risk-benefit analysis of radiation exposure; states that somatic and genetic effects should be kept to a minimum when radiation is used for diagnostic imaging
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
lifetime occupational exposure must not exceed the radiographer’s age multiplied by 10 mSv
Equivalent dose
equal to the effective dose multiplied by the radiation weighting factor
As low as reasonably achievable (ALARA)
concept of radiologic practice that encourages radiation users to adopt measures that keep the dose to the patient and themselves at minimum 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
Probablistic (stochastic) 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 become more severe at high level 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 versus an entire population and the overall effects
Linear energy transfer (LET)
amount of energy deposited by radiation per unit length of tissue
Relative biological 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: 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; gastrointestinal syndrome; central nervous system syndrome
Late somatic effects of radiation
carcinogenesis; cataractogenesis; embryologic effects; thyroid dysfunction; life span shortening
Cardinal principles of radiation protection
distance, time, shielding
Distance
best protection against radiation exposure
Personnel monitoring devices
optically stimulated luminescence (OSL) badge, film badge, thermoluminescent dosimeter (TLD)
Mean marrow dose
average dose of radiation to the bone marrow
