a series of steps that collectively produces a visible permanent image on a dental radiograph
film processing
purposes of film processing
convert the latent (invisible) image on the film into a visible image
to preserve the visible image so that it is permanent and does not disappear from the denta radiograph
the portion of a processed radiograph that is dark or black
radiolucent
what type of structures appear radiolucent on an x-ray?
structures that lack densiy and permit the passage of the x-ray beam with little or no resistance
the portion of a processed radiograph that appears lightr white
radiopaque
what type of structures appear radiopaque?
structures that are dense and absorb or resist the passage of the x-ray beam including, enamel,dentin, and bone
Diagnostic radiograph produces images that;
exhibit proper density and contrast
have sharp outlines
are the same shape and size as the object being radiographed
visual characteristics of dental radiograph
density
contrast
the overall blackness or darkness of a dental radiograph
density
what 3 things does a radiograph with correct density allow the radiographer to view?
black areas - air space
white areas - enamel, dentin, and bone
gray areas - soft tissue
3 exposure factors that control the density of a radiograph
milliamperage (mA)
operating kilovoltagepeak (kVp)
exposure time
true or false. Subject thickness/size and density of the bone also affect the overall density of a radiograph
true
How does an increase in milliamperage affect the film density of a radiograph?
it produces more x-rays exposed to the film and increases the film density, so it appears darker
How does an increase in operating kilovoltage peak affect the density of the radiograph?
it increases the film density by increasing the average energy of the x-rays by producing x-rays with higher energy. the film appears darker
How does an increase of exposure time affect the densiy of the radiograph?
it increases the film density by increasing the total number of x-rays that reach the film surface. the film appears darker
the difference in the degrees of blackness (densities) between adjacent areas on a dental radiograph
contrast
the difference in the amount of light transmitted through adjacent areas of a radiograph
contrast
very light and very dark areas that are strikingly different
high contrast
many shades of gray
low contrast
how is contrast determined?
by film contrast and subject contrast
characteristics of the film that influence radiographic contrast
film contrast
what type of characteristics influence the contrast of the film?
inherent qualities
film processing
who controls the inherent qualities of the film
the manufacturer
who controls film processing of the radiograph?
the dental radiographer
true or false. an increase in development time or temperature increases the contrast of the film.
true
the characteristics of the subject that influences radiographic contrast
subject contrast
what type of characteristics is subject contrast determined by?
thickness
density
composition (atomic number) of subject
how is subject contrast altered? And how does this affect the outcome?
by adjusting the kVp
high operating kilovoltage peak (more than 90) = low contrast
low operating kilovoltage peak (60-75) = high contrast
what is the one exposure factor that has a direct influence on contrast of the radiograph?
kilovoltage peak
How does the kilovoltage peak directly affect the contrast?
increasing the kilovoltag peak increases the average energy of the x-rays produced allowing them to penetrate tissue better which results in more variations in tissue on the film with varying shades of gray, or low contrast
the range of useful densities seen on a dental radiograph
scale of contrast
a dental radiograph that shows only 2 densities, areas of black and white show what scale of contrast
short-scale contrast
a lower kVp results in a radiograph with ____________-scale contrast, which can also be described as having______________ contrast.
short
high
a dental radiograph that exhibits many densities or many shades of grey exhibits which kind of contrast?
long-scale contrast
a higher kVp range results in a radiograph with _________-scale contrast and ______________contrast
long
low
a device used to demonstrate short-scale and long-scale contrast
stepwedge
name the 3 geometric characteristics of the radiographic image
sharpness
magnification
distortion
the capability of the x-ray film to reproduce the distinct outlines of an object or, in other words, to how well the smallest details of an object are reproduced on dental radiograph
sharpness
unsharpness, or blurring of the radiographic image that is present in every radiograph.
penumbra
what are the 3 factors that influence sharpness of a radiograph?
focal spot size
film composition
movement
what are the meanings of the latin words pene, and umbra?
almost
shadow
the tungsten target of the anode, which converts bombarding electron into x-ray photons, and concentrates the electrons and creates an enormous amount of heat.
focal spot
what is the size of the focal
.6mm2 to 1.0mm2
the smaller the focal spot area, the ___________the image appears; the larger the focal point size, the_____________the loss of image sharpness.
sharper
greater
what is relative to the size of the crystals found in the film emulsion?
sharpness
what type of crystals does the emulsion of faster film contain?
larger crystals that produce less image sharpness
what type of crystals does the emulsion of slower film contain?
smaller crystals that produce that produce more image sharpness
true or false. Movement of either the film or the patient influences film sharpness
true
a radiographic image that appears larger than the actual size of the object it represents
magnification
what are the 2 factors that influence the image magnification on a target radiograph?
target-film distance
object-film distance
distance between the source of x-rays (focal spot on the tungsten target) and the film
target-film distance
what determines the target-film distance?
the length of the position indicating device
a longer PID and target-film distance result in__________image magnification, and a shorter PID and target-film distance result in____________image magnification
less
more
distance between object being radiographed (tooth) and the dental x-ray film
object-film distance
a decrease in object-film distance results in a______________in magnification, and an increase in object-film distance results in an___________ in magnification
decrease
increase
a variation in the true size and shape of the object being radiographed
distortion
what causes a distorted image?
unequal magnification of different parts of the same object
improper film alignment or angulation of x-ray beam
what influences the dimensional distortion of a radiograph?
object-film alignment
x-ray beam angulation
how must the object and film be situated to avoid distortion?
parallel to eachother
how should the x-ray beam angulation be situated to the tooth to prevent distortion?