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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. |