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Radiology

Final Review

The study of radiation? Radiology
Image or picture produced by x-rays? Radiograph
An older tern given to x-radiation in honor of its discoverer? Roentgen Ray
The original term Roentgen applied to the invisible ray he discovered? X-ray
The making of radiographs by exposing and processing x-ray film? Radiography
Who discovered the x-ray? Wilhelm Roentgen
When were x-rays discovered? Nov. 8, 1895
Who is believed to have exposed the prototype of the first dental x-ray? Otto Walkhoff
Five uses of dental radiographs? Oral diseases and lesions. Trauma. Growth/Development. Missing/supernumerary teeth. Document oral pt condition. Educate pts about their oral health.
Which electromagnetic radiation has the shortest wavelength? X-rays
Which form of radiation has the greatest penetrating power? X-rays
Five properties of x-rays? Invisible. Straight line. No weight. No charge. Travels at speed of light.
Radiation produced when high-speed electrons are stopped or slowed down by the tungsten atoms of the dental x-ray tube? General/Bremsstrahlung radiation.
The transfer of x-ray energy to the atoms of the material through which the x-ray beam passes? Absorption.
Three sources of background radiation? Cosmic Radiation-Outer space. Terrestrial Radiation-Earth. Background Radiation-natural occurring radionuclides
Radiant energy sufficient to remove an electron from its orbital level of an atom is called? Ionizing
Radioactivity Unstable atoms undergo decat in an effort to obtain nuclear stability.
Wavelength Distance between two similar points on two successive waves called.
Which activates the x-ray production process? Exposure button.
To produce a larger quantity of electrons available to produce x-rays increase the mA's
Voltage The electrical pressure (difference in potential) between two electrical charges.
Three conditions that must exist for x-rays to be produced. Source of free electrons. High voltage to impart speed to the electrons. A target that is capable of stopping/slowing down the electrons.
Thermionic Emisison Heating the cathode wire filaments until red hot and electrons boil off.
What metal is used for the large in the x-ray tube? Tungsten
What percent of kinetic energy inside the x-ray tube is converted into x-rays? 1%
What percent of kinetic energy is given off as heat? 99%
Criteria for an acceptable radiograph? All parts of the structures imaged must be as close to their natural shapes. The area examined must be imaged completely, Free of errors and show proper density, contrast, and definition.
Density The darkness of the radiograph.
Penumbra Fuzzy shadow around the outline of the radiograph
When does distortion occur? Object and image receptor are not parallel.
The dental radiograph will appear less dense (lighter) if one increases the TFD
The primary cause of biological damage from radiation is ionization
Direct injury from radiation occurs when the x-ray photons strike critical cell molecules
Indirect injury from radiation occurs when the x-ray photons ionize water and form toxins.
Most radiosensitive cells White blood cells
Most radio resistant cells Muscle cells
Sequence of events following radiation exposure? Latent period. Period of injury. Recovery period.
Full term, low birth weight is possibly associated with radiation exposure to what organs? Thyroid gland, hypothalamus, or pituitary gland.
What is the minimum total filtration that is required by an x-ray machine that can operate in ranges above 70kVp? 2.5 mm of aluminum equivalent
Diameter of the primary beam at the end of the PID (at the skin of the patients face) 2.5 inches
Which PID size exposes the patient to less radiation? 16in Rectangular PID
Minimum distance the operator should stand away from the source of radiation? 6 feet.
Yearly maximum permissible dose for the health care worker? 50mSv
Yearly maximum permissible dose for the general public? 5mSv
T/F- Silver halide crystals are light and x-ray sensitive? True
During x-ray exposure crystals within the film emulsion become energized with a Latent Image
Function of the lead foil in the film packet? Absorb backscatter radiation
Which film speed has the greatest sensitivity to radiation? F speed
What is the purpose of intensifying screens? Reduce exposure time.
What is the function of the lead apron? To protect the patient by stopping and absorbing radiation.
Which process does the latent image become visible? Reduction
During what step of processing procedure are the exposed silver halide crystals reduced to metallic silver? Developing step
Which chemical removes the unexposed/undeveloped silver halide crystals from the film emulsion? Sodium Thiosulfate
Which chemical causes the emulsion to soften and swell? Activator
Which chemical hards the emulsion? Potassium Alum
Which color of safelight filter is safe for processing all film speeds? Red
Minimum safe distance to position the safelight above the work area? 4 ft.
Appearance of a film if exposed to a safelight too long? Fogged
Ideal temperature for processing manual film for how long? 68F for 5 minutes
Developing Agents Hydroquinone-slowly builds black tones. Elon- quickly builds gray tones.
Preservative Sodium Sulfite- prevents rapid oxidation.
Activator Sodium Carbonate- Activates developing agents
Restrainer Potassium Bromide- Restrains developing agents from developing the unexposed silver halide crystals.
Fixer agent Sodium Thiosulfate- removes the unexposed/underdeveloped silver halide crystals.
Hardening agent Potassium alum- shrinks and hardens the gelatin emulsion.
Acidifer Acetic Acid- Stops further development.
Increased vertical angulation results in foreshortening or elongation of the teeth? Foreshortening
Placing the film backwards in the mouth results in? The herring bone effect.
Created by: Strobelight95