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189 Cards in this Set

  • Front
  • Back

Incidence of malignant disease in a population within 1 year for a given dose; expressed as number of cases/106 persons/rem.

Absolute risk
Energy transferred from ionizing radiation per unit mass of irradiated material; expressed in rad (100 erg/g) or gray (1 J/kg).
Absorbed dose
Radiation sickness that occurs in humans after whole-body doses of 1 Gy (100 rad) or more of ionizing radiation delivered over a short time.
Acute radiation syndrome

Pattern of change in radiosensitivity as a function of phase in the cell cycle.

Age-response function
Principle that states that radiation exposure should be kept As Low As Reasonably Achievable, when economic and social factors are taken into account.
ALARA
Third phase of mitosis, during which chromatids repel one another and migrate along the mitotic spindle to opposite sides of the cell.
Anaphase

Shrinking of a tissue or organ.

Atrophy
Special name for the SI units of radioactivity. One _______ is equal to disintegration per second.
Becquerel (Bq)
Protective cover that automatically shields the Bucky slot opening during fluoroscopic examinations when the Bucky tray is at the foot of the table.
Bucky slot cover
Process that creates energy for a cell by breaking down molecular nutrients that are brought to and diffused through the cell membrane.
Catabolism
Basic unit of all living matter.
cell
Agency responsible for a national electronic radiation control program. Known as the Bureau of Radiological Health (BRH) before 1982.

Center for Diseases and Radiological Health (CDRH)

Form of acute radiation syndrome caused by radiation doses of 50 Gy (5000 rad) or more of ionizing radiation that results in failure of the central nervous system, followed by death within a few hours to several days.
Central nervous system (CNS) syndrome
Chromatid deletion
Breakage of a chromatid.
Restriction of the useful x-ray beam to reduce patient dose and improve image contrast.
collimation
Scattering of x-rays that results in ionization and loss of energy
Compton
Shields that are flat and are placed directly on the patient's gonads.
Contact shields
SI unit of radiation exposure: 2.58×10−4 C/kg=1 R
Coulomb per kilogram (C/kg)
Former unit of radioactivity.
Curie (Ci)
Protoplasm that exists outside the cell's nucleus.
Cytoplasm
Nitrogenous organic base that attaches to a deoxyribose molecule
Cytosine
Molecule that carries the genetic information necessary for cell replication; the target molecule of radiobiology.
Deoxyribonucleic acid (DNA)
Ulceration and denudation of the skin.
Desquamation
Biologic response whose severity varies with radiation dose. A dose threshold usually exists.
Deterministic effect
Effect of radiation that occurs when ionizing radiation interacts directly with a particularly radiosensitive molecule
Direct effect
Amount of radiant energy absorbed by an irradiated object.
Dose
Radiation quantity that is used for radiation protection and that expresses dose on a common scale for all radiation. Expressed in rem or sievert (Sv).
Dose equivalent (H)
Maximum permissible occupational radiation dose.
Dose Limit (DL)
Instrument that detects and measures exposure to ionizing radiation.
Dosimeter
The practice of measuring the intensity of radiation
Dosimetry
Configuration of DNA that is shaped like a ladder twisted about an imaginary axis like a spring.
Double-helix
That dose of radiation that is expected to double the number of genetic mutations in a generation
Doubling dose
Radiation response that occurs within minutes or days after radiation exposure
Early effect
Sum of specified tissues of the products of equivalent dose in a tissue (HT) and the weighting factor for the tissue (WT). Effective dose is a method of converting a nonuniform radiation dose, as when a protective apron is worn, to a dose, with respect to risk, as if the whole body were exposed.
Effective dose (E)
Sum of the products of the dose equivalent to a tissue (HT) and the weighting factors (WT) applicable to each of the tissues irradiated. The values (WT) are different for effective dose and effective dose equivalent.
Effective dose equivalent (HE)
Damage that occurs as the result of exposure of an organism to ionizing radiation during its embryonic stage of development
Embryologic effect
Channel or series of channels that allows the nucleus to communicate with the cytoplasm
Endoplasmic reticulum
X-ray exposure to the skin; expressed in milliroentgen (mR).
Entrance skin exposure (ESE)
Study of the occurrence, distribution, and causes of disease in humans.
Epidemiology
Loss of hair.
Epilation
Covering tissue that lines all exposed surfaces of the body, both exterior and interior.
Epithelium
Sunburn-like reddening of the skin.
Erythema
Red blood cell.
Erythrocyte
Difference between observed and expected numbers of cases.
Excess risk
Measure of the ionization produced in air by x-rays or gamma rays. Quantity of radiation intensity expressed in roentgen (R), Coulombs per kilogram (C/kg), or air kerma (Gy).
Exposure
Pack of photographic film used for approximate measurement of radiation exposure to radiation workers. It is the most widely used and most economical type of personnel radiation monitor.
Film badge
Radiation dose delivered at the same dose in equal portions at regular intervals
Fractionated
Uncharged molecule that contains a single unpaired electron in the valence shell.
Free radical
Form of acute radiation syndrome that appears in humans at a threshold dose of about 10 Gy (1000 rad). It is characterized by nausea, diarrhea, and damage to the cells lining the intestines.
Gastrointestinal (GI) syndrome
Radiation detection and radiation measuring instrument that detects individual ionizations. It is the primary radiation survey instrument for nuclear medicine facilities.
Geiger-Muller (G-M) counter
Average gonadal dose given to members of the population who are of childbearing age.
Genetically significant dose (GSD)
Genetic cell
Oogonium or spermatogonium.
Effect of radiation that is seen in an individual and in subsequent unexposed generations.
Genetic effect
reproductive cell
Germ cell
Glandular dose
Average radiation dose to glandular tissue.
Exposure to the reproductive organs.
Gonadal dose
Granulocyte
Scavenger cell used to fight bacteria
Special name for the SI unit of absorbed dose and air kerma.
Gray (Gy)

1 Gy=1 J/kg=100 rad.
Nitrogenous organic base that attaches to a deoxyribose molecule.
Guanine
Time required for a quantity of radioactivity to be reduced to half its original value.
Half-life
Thickness of absorber necessary to reduce an x-ray beam to half its original intensity.
HVL
The science that is concerned with the recognition, evaluation, and control of radiation hazards
Health physics
Form of acute radiation syndrome that develops after whole-body exposure to doses ranging from approximately 1 to 10 Gy (100 to 1000 rad). It is characterized by reduction in white cells, red cells, and platelets in circulating blood.
Hematologic syndrome
Radiation interaction with the target.
HIT
a. State of equilibrium among tissue and organs. b. Ability of the body to return to normal function despite infection and environmental changes.
Homeostasis
Protein manufactured by various endocrine glands and carried by the blood to regulate body functions such as growth and development.
Hormone
Effect of radiation that results from the production of free radicals produced by the interaction of radiation with water
Indirect effect
Period of growth of the cell between divisions.
Interphase
Law that states that the intensity of radiation at a location is inversely proportional to the square of its distance from the source of radiation
Inverse square law
This means, "In the living cell".
In vivo
Instrument that detects and measures the radiation intensity in areas outside of protective barriers.
Ion chamber
Referring to an atom that has an extra electron or has had an electron removed.
Ionized
Referring to matter that intercepts radiation and absorbs part or all of it; exposed.
Irradiated
Fragment in a chromosome aberration.
Isochromatid
Energy absorbed per unit mass from the initial kinetic energy released in matter of all the electrons liberated by x-rays or gamma rays. Expressed in gray (Gy). 1 Gy=1 J/kg.
Kerma (k)
Radiation response that is not observed for 6 months or longer after exposure.
Late effect
Period after the prodromal stage of the acute radiation syndrome during which no sign of radiation sickness is apparent.
Latent period
Principle that states that the radiosensitivity of cells is directly proportional to their reproductive activity and inversely proportional to their degree of differentiation.
Law of Bergonié and Tribondeau
Dose of radiation expected to cause death within 60 days to 50% of those exposed.
LD50/60
Measure of the rate at which energy is transferred from ionizing radiation to soft tissue. Expressed in kiloelectron volts per micrometer of soft tissue.
LET
Referring to the dose-response relationship that intersects the dose axis at or below zero.
Linear, nonthreshold
Referring to the dose-response relationship that intercepts the dose axis at a value greater than zero.
Linear, threshold
White blood cell that plays an active role in providing immunity for the body by producing antibodies; it is the most radiosensitive blood cell.
Lymphocyte
Cell that contains enzymes capable of digesting cellular fragments.
Lysosome
Breakage of the long-chain macromolecule that divides the long, single molecule into smaller ones.
Main-chain scission
Stage of acute radiation syndrome during which signs and symptoms are apparent.
Manifest image
Dose of occupational radiation that would be expected to produce no significant radiation effects. An old expression. Replaced by Dose Limit.
Maximum permissible dose (MPD)
Constant related to the radiosensitivity of a cell.
Mean lethal dose
Average radiation dose to the entire active bone marrow.
Mean marrow dose (MMD)
Average time between exposure and death.
Mean survival time
Physicist who examines and monitors the performance of imaging equipment.
Medical physicist
Process of germ cell division that reduces the chromosomes in each daughter cell to half the number of chromosomes in the parent cell.
Meiosis
Anabolism and catabolism
Metabolism
Phase of cell division during which the chromosomes are divisible.
Metaphase
Structure that digests macromolecules to produce energy for the cell
Mitochondrion
Process of somatic cell division wherein a parent cell divides to form two daughter cells identical to the parent cell.
Mitosis (M)
Monosaccharide
A sugar
Model of radiation dose-response relationship for more complicated biologic systems, such as human cells.
Multitarget or single-hit model
Organization that continuously reviews recommended dose limits.
National Council on Radiation Protection and Measurement (NCRP)
Naturally occurring ionizing radiation, including cosmic rays, terrestrial radiation, and internally deposited radionuclides.
Natural environmental radiation
Radiation for which the mechanism of action in tissue does not directly ionize atomic or molecular systems through a single interaction
Nonionizing radiation
Referring to varied responses that are produced from varied doses, with any dose expected to produce a response
Nonlinear, nonthreshold
Referring to varied responses that are produced from varied doses, with a particular level below which there is no response.
Nonlinear, threshold
Biologic effects of ionizing radiation that demonstrate the existence of a threshold. Severity of biologic damage increases with increased dose. (See Determination Effects.)
Nonstochastic effects
Rounded structure that often is attached to the nuclear membrane and controls the passage of molecules, especially RNA, from the nucleus to the cytoplasm.
Nucleolus
a. Center of a living cell; spherical mass of protoplasm that contains the genetic material (DNA) that is stored in its molecular structure. b. Center of an atom that contains neutrons and protons.
Nucleus
Dose received by an individual in a restricted area during the course of employment in which the individual's assigned duties involve exposure to radiation.
Occupational dose
Radiation exposure received by radiation workers.
Occupational exposure
Primordial follicles that grow to encapsulate oogonia.
Oocytes
Mature germ cell in a female
Ovum
Ratio of the dose necessary to produce a given effect under anoxic conditions to the dose necessary to produce the same effect under aerobic conditions
Oxygen enhancement ratio (OER)
Interaction between the x-ray and the nuclear electric field that causes the x-ray to disappear and that causes two electrons—one positive and one negative—to take its place.
Pair production
Radiation distinct from x-rays and gamma rays; examples include alpha particles, electrons, neutrons, and protons
Particulate radiation
Process by which very high-energy x-rays can escape interaction with electrons and the nuclear electric field and can be absorbed directly by the nucleus.
Photodisintegration
Electron that has been removed during the process of photoelectric absorption
Photoelectron
Absorption of an x-ray by ionization
Photoelectric effect
Any change that results in impairment or loss of function at the point of a single chemical bond.
Point lesion
Molecular lesion caused by the change or loss of a base that destroys the triplet code and may not be reversible.
Point mutation
Large carbohydrate that includes starches and glycogen.
Polysaccharide
Feature of radiographic collimators that automatically adjusts the radiation field to the size of the image receptor.
Positive beam limiting (PBL)
An immature cell
Precursor cell
Any wall to which the useful beam can be directed.
Primary protective barrier
First stage of the acute radiation syndrome; occurs within hours after radiation exposure.
Prodromal period
Phase of cell division during which the nucleus and the chromosomes enlarge and the DNA begins to take structural form
Prophase
Metabolic production of proteins
Protein synthesis
Dose of radiation that is delivered continuously but at a lower dose rate.
Protracted dose
Special unit for absorbed dose and air kerma.
Rad (radiation absorbed dose)
Branch of biology that is concerned with the effects of ionizing radiation on living systems.
Radiation biology
Energy emitted and transferred through matter
Radiation
Theory that suggests that very low radiation doses may be beneficial.
Radiation hormesis
Intensity of radiation; usually measured in milliroentgen (mR).
Radiation quantity
Recommendations, rules, and regulations regarding permissible concentrations, as well as safe handling techniques, transportation, and industrial control of radioactive material.
Radiation standards
Factor used for radiation protection that accounts for differences in biologic effectiveness between different radiations. Formerly called quality factor.
Radiation weighting factor (WR)
Naturally occurring process whereby an unstable atomic nucleus relieves its instability through the emission of one or more energetic particles.
Radioactive decay
Process by which the nucleus spontaneously emits particles and energy and transforms itself into another atom to reach stability.
Radioactive disintegration
Time required for a radioisotope to decay to half its original activity.
Radioactive half-life
Rate of decay or disintegration of radioactive material. Expressed in curie (Ci) or becquerel (Bq). 1 Ci=3.7×1010 Bq.
Radioactivity
Dissociation of water into other molecular products as a result of irradiation.
Radiolysis of water
Any nucleus that emits radiation.
Radionuclides
Relative susceptibility of cells, tissues, and organs to the harmful action of ionizing radiation
Radiosensitivity
Colorless, odorless, naturally occurring radioactive gas (222Ra) that decays via alpha emission and has a half-life of 3.8 days
Radon
Repair and repopulation
Recovery
Increased incidence of a disease proportional to its natural incidence.
Relative age-response relationship
Ratio of the dose of standard radiation necessary to produce a given effect to the dose of test radiation needed for the same effect.
Relative biologic effectiveness (RBE)
Estimation of late radiation effects in large populations without precise knowledge of their radiation dose.
Relative risk
Special unit for dose equivalent and effective dose. It has been replaced by the sievert (Sv) in the SI system.
Rem (radiation equivalent man)
Replication by surviving cells.
Repopulation
Molecules that are involved in the growth and development of a cell through a number of small, spherical cytoplasmic organelles that attach to the endoplasmic reticulum.
Ribonucleic acid (RNA)
The site of protein synthesis.
Ribosomes
Barrier designed to shield an area from secondary radiation.
Secondary protective barrier
Leakage and scatter reaction.
Secondary radiation
Dose of radiation to which the external skin or an extremity is exposed.
Shadow dose equivalent (HS)
Shield that is suspended over the region of interest; it casts a shadow over the patient's reproductive organs
Shadow shield
Special name for the SI unit of dose equivalent and effective dose.
Sievert (Sv)

1 Sv=1 Jkg=100 rem.
Nonlinear, threshold radiation dose-response relationship.
Sigmoid-type (S-type) dose-response relationship
Model of radiation dose-response relationships for enzymes, viruses, and bacteria.
Single-target hit model
Dose of radiation, usually about 200 rad or 2 Gy, that causes redness of the skin.
Skin erythema dose (SED)
All cells of the body except the oogonium and the spermatogonium.
Somatic cells
Effects of radiation, such as cancer and leukemia, limited to an exposed individual. See also Genetic effect.
Somatic effects
Mature spermatogonium.
Spermatocyte
Spermatogonium
Male germ cell.
Functionally mature male germ cell.
Spermatozoa
Fibers that connect a centromere and two chromatids to the poles of the nucleus during mitosis
Spindle fibers
Poles of the nucleus
Spindles
A plant polysaccharide
Starch
Immature or precursor cell.
Stem cell
Probability or frequency of the biologic response to radiation as a function of radiation dose. Disease incidence increases proportionally with dose, and there is no dose threshold.
Stochastic effects
a. Region of an x-ray tube anode that is struck by electrons emitted by the filament. b. Molecule (DNA) that is most sensitive to radiation.
Target
Molecules (DNA) that are few in number yet essential for cell survival; they are particularly sensitive to the effects of ionizing radiation.
Target molecules
Theory that a cell will die if target molecules are inactivated as a result of radiation exposure.
Target theory
Final subphase of mitosis that is characterized by the disappearance of structural chromosomes into a mass of DNA and the closing off of the nuclear membrane into two nuclei.
Telophase
Thickness of an absorber necessary to reduce an x-ray beam to one-tenth its original intensity. _______=3.3 half-value layers.
Tenth-value layer (TVL)
Radiation emitted from deposits of uranium, thorium, and other radionuclides in the Earth.
Terrestrial radiation
Emission of light by a thermally stimulated crystal after irradiation.
Thermoluminescence dosimetry
Dose below which a person has a negligible chance of sustaining specific biologic damage, or dose at which response to increasing x-ray intensity first occurs.
Threshold dose
Circular or oval disc called a platelet; it is found in the blood, and it initiates blood clotting and prevents hemorrhage
Thrombocyte
Nitrogenous organic base that attaches to a deoxyribose molecule.
Thymine
Length of time that the area being protected is used.
Time-of-occupancy factor (T)
Proportion of risk of stochastic effects that result from irradiation of the whole body when only an organ or tissue is irradiated; accounts for the relative radiosensitivity of various tissues and organs.
Tissue weighting factor (WT)
Recommendation by the National Council on Radiation Protection and Measurement that a radiation worker's lifetime effective dose should be limited to the worker's age in years multiplied by 10 mSv.
Total effective dose (TED)
Process of constructing mRNA
Transcription
Addition of an amino acid during translation.
Transfer
Process of forming a protein molecule from messenger RNA.
Translation
Area occupied by anyone; the maximum exposure rate allowed in this area is based on the recommended dose limit for the public.
Uncontrolled area
Immature or nonspecialized cell.
Undifferentiated cell
Proportional amount of time during which the x-ray beam is energized or directed toward a particular barrier.
Use factor (U)
For purposes of external exposure, the head, trunk (including gonads), arm above the elbow, and leg above the knee.
Whole body
Radiographic exposure in which the whole body, rather than an isolated part, is irradiated.
Whole-body exposure
Product of the maximum milliamperage (mA) and the number of x-ray examinations performed per week. Expressed in milliamperes per minute per week (mA/min/wk).
Workload (W)