Chapter 4 Flashcards
What does the inverse square law state about radiation intensity?
The intensity of the radiation decreases as the distance away from its source increases, because the beam of radiation diverges.
What term refers to a radiographic image that is black and white with many shades of gray in between?
Low contrast
Low contrast (also called long-scale contrast) describes a radiograph in which the density differences between adjacent areas are small.
What indicates a radiographic image that is black and white with few shades of gray in between?
Short scale
Short-scale contrast (also called high contrast) describes a radiograph in which the density differences between adjacent areas are large.
What are white areas on a radiographic image termed?
Radiopaque
Is it true that radiographic density is decreased when the milliamperage or exposure time is increased?
FALSE
Does short-scale contrast describe a radiograph with small density differences between adjacent areas?
FALSE
Does increasing the kV result in a more penetrating x-ray beam?
TRUE
What does sharpness/definition refer to in radiography?
The detail and clarity of the structures on a radiograph.
Does a small focal spot reduce penumbra?
TRUE
What do grids do in radiography?
Grids absorb scattered x-rays.
What is the ideal focal spot theoretically?
A point source.
Should the target-image receptor distance be short for the best definition in radiographs?
FALSE
Should the film be in close physical contact with the intensifying screens?
TRUE
Is a radiographic image with many shades of gray said to have low contrast?
TRUE
What is the portion of the radiographic image that appears light called?
Radiopaque
Is penumbra a device used in extraoral radiography to prevent scatter radiation?
FALSE
Do some clinicians prefer low contrast radiographic images while others prefer high contrast?
TRUE
What generally causes radiographic image unsharpness?
Movement of the patient, image receptor, or tube head during exposure.
Can digital imaging sharpness be affected by pixel size and distribution?
TRUE
Do thicker intensifying screens increase the sharpness of extraoral radiographs?
FALSE
What is the distance between the focal spot on the target and the skin surface of the patient called?
Target-surface distance.
Should only one film be placed in contact with the intensifying screens used for extraoral radiography?
TRUE
Does slight movement of the tube head during exposure effectively increase the size of the focal spot?
TRUE
What types of tissues or structures appear radiolucent on radiographs?
Soft tissues, such as the pulp chamber.
What types of tissues or structures appear radiopaque on radiographs?
Hard tissues, such as enamel, dentin, and bone.
What is radiographic density?
The degree of image blackening (darkening).
What is short-scale contrast?
A radiograph that displays black, white, and few shades of gray.
What is the relationship between kVp and contrast?
kV and contrast have an inverse relationship.
Why should the x-ray film be placed parallel to the long axis of the tooth?
To minimize distortion.
What determines the quality of the beam of radiation?
kV.
What is radiographic contrast?
How sharply dark and light areas are differentiated.
What is long-scale contrast?
A radiograph in which density differences between adjacent structures are small.
What is penumbra?
The fuzzy, unsharp zone around objects on a radiograph.
