Chapter 8: Dental xray Image characteristics Flashcards
A structure that appears _______ lacks density and permits the passage of the x-ray beam with little or no resistance.
radiolucent
refers to that portion of an image that appears light or white.
Radiopaque
provides a great deal of information; the images exhibit proper density and contrast, are of the same shape and size as the object exposed, and have sharp outlines.
diagnostic image
Two visual characteristics that directly influence the diagnostic quality of a dental image.
density and contrast
three exposure factors control the density of a dental image, as follows:
kilovoltage
milliamperage
exposure time
higher mA = ____ density = darker
higher
higher kV = _______ density
higher
higher exposure time = _______ density
higher
higher subject thickness = _______ density
lower
higher kV=_______ scale contrast
long scale contrast
lower kV= _______ scale contrast
short scale contrast
If the kilovoltage is increased, the density increases, and the image appears __________
darker
if kilovoltage is decreased, the density decreases, and the image appears ___________
lighter
Density is directly related to ______ ____
exposure time
An image that does not have very dark and very light areas but instead has many shades of gray demonstrates ______ _____ .
low contrast
When viewed on a light source, a dental image that has very dark areas and very light areas demonstrates ____ ______
high contrast
refers to the characteristics of the film that influence radiographic contrast
film contrast
Development time or the temperature of the developer solution affects the contrast of a dental radiograph. For example, an increase in development time or developer temperature results in a film with high contrast. TRUE OR FALSE
TRUE
subject contrast
characteristics of the subject that influence radiographic contrast.
X-rays with higher energy are better able to penetrate tissue. T or F
True
A dental image that shows only two densities, areas of black and areas of white has a ___ _____ scale
short contrast scale
An image that exhibits a short contrast scale can also be described as having high contrast, in which the _____ and ______ areas are easily distinguished from each other
black and white
A dental image that exhibits many densities, or many shades of gray, has a ____ _____ scale
long contrast scale
A device known as a _______can be used to demonstrate short-scale contrast and long-scale contrast.
stepwedge
used to monitor the qualities of the film, the film processing, and the digital sensor, as well as calibration of the x-ray machine
stepwedge
Three geometric characteristics that influence the diagnostic quality of a dental image :
sharpness
magnification
distortion
(also known as detail, resolution, or definition) refers to the capability of the receptor to reproduce the distinct outlines of an object
sharpness
unsharpness, or blurring, of the edges.
penumbra
The sharpness of an image is influenced by the following three factors:
focal spot size
film composition
movement
the tungsten target of the anode serves as a ____ ____ this small area converts bombarding electrons into x-ray photons.
focal spot
The size of the focal spot ranges from _____ to _____
0.6 , 1.0 mm
The smaller the focal spot area, the ______the image; the larger the focal spot area, the greater the loss of ____ _____
sharper
image sharpness
The composition of the film emulsion influences sharpness. T or F
TRUE
refers to a radiographic image that appears larger than the actual size of the object it represents.
magnification
Magnification, or enlargement of a radiographic image, results from the diverging x-ray beam. TRUE OR FALSE
TRUE
The magnification on a dental image is influenced by the following:
target receptor distance
object- receptor distance
target receptor distance
distance between source of xrays and the image receptor
which PID results in less image magnification? Longer PID or shorter PID
longer PID and target receptor distance.
Longer PID limits magnification
Object receptor distance
distance between the object being radiographed and the image receptor
A decrease in object-receptor distance results in a decrease in magnification, and an increase in object-receptor distance results in an increase in image magnification . T OR F
TRUE
distortion of a radiographic image is a variation in the true size and shape of the object being radiographed. This type of image does not have the same size and shape as the object being radiographed .
distortion
The dimensional distortion of a radiographic image is influenced by the following
Object receptor alignment
x-ray beam angulation
To minimize dimensional distortion, the object and receptor must be______ to each other.
parallel
To minimize dimensional distortion, the x-ray beam must be directed ________to the tooth and the receptor.
perpendicular
Of the three exposure factors only the ______ has a direct influence on contrast
Kilovoltage