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Contrast & Density

Contrast info, Density info

QuestionAnswer
An H & D curve demonstrating a steep curve represents film with ______? High contrast
How does the use of grids affect the contrast of a radiograph? Produces higher contrast
Subject contrast is caused by? Tissue density differences, atomic number, and body part thickness
List the body parts in order from less absorbing power to more absorbing power. Air, Fat, Water, Muscle, and Bone
Adding air to a body part ______ its tissue density compared to the structures around it. Decreases
Adding iodine or barium to a body part ______ its tissue density compared to the structures around it. Increases
What is the main controlling factor for radiographic contrast? kVP
The radiation that goes through the patient's body is called? Exit radiation or remnant radiation
Scattered radiation ________ radiographic contrast. Lowers
3 most common contrast agents Air, Barium and Iodine
Adding air <increases/decreases> radiographic density Decreases
As x-ray photons are absorbed, scattered, or pass through, the intensity of the beam is reduced. this is called _______. Attenuation
________ refers to the ability of a film to record a wide range of densities. Film latitude
Low energy radiation will result in ______ ____ contrast. Short scale
How will high kvp techniques affect radiographic contrast? Produce lower contrast
The quality of an x-ray beam is determined by? kVp
How will increasing screen speed affect radiographic quality? Produce higher contrast
Which grid ratio should be used to maintain contrast when using over 100 kvp? 12:1
The number of density difference in a radiograph refers to what? Scale of contrast
How does a small increase indeveloper temperature affect radiographic contrast? Produces higher contrast
Subject contrast will be the lowest with which body habitus? Hyperstenic
What accessory can be used to demonstrate a scale of contrast or test for contrast? Penetrometer
How will an air gap technique affect radiographic contrast? Produce higher contrast
Contrast can be measured from an H & D curve by finding the slope of the ________ ________. Highest contrast
Long wavelength radiation will result in _____ scale contrast. Short
What type of relationship occurs with contrast when mAs increases? Inverse relationship
What type of relationship occurs with contrast when SOD increases? Inverse relationship
What type of relationship occurs with contrast when tube angle increases? No change
Why is contrast needed in a radiographic image? Makes detail visible.
How does an increase in developer temperature affect contrast? Contrast decreases.
As contrast decreases, how is the number of densities in the film affected? Increases
As motion increases, what happens to contrast? Motion has no effect on contrast.
Define contrast. Difference between adjacent densities.
A visible change in kVp is not seen until kVp is changed __ to __%, depending on kVP range. 4, 12
What are the two types of radiographic contrast? Film and subject contrast
Define film contrast. The range of densities that the image is capable of recording.
Define subject contrast. Range of differences in the intensity of the x-ray beam after it has been attenuated by the subject.
What happens to contrast if collimation is increased? Decreased contrast
Density is one of the two ________ properties comprising visibility of detail. Photographic
Increments of 0.3 changes in optical density numbers represent a ________ or ________ of opacity. Doubling, halving
Image density/brightness on the display monitor is controlled by __________ ________ Window levelling
The ______________ _______ states film density should remain unchanged as long as the intensity and duration of x-ray exposure remains unchanged. Reciprocity law
When kVp ranges 30 - 50, a __ to ___ percent change in kVP can be detected. 4 to 5
A __ to ___ percent change in kVp is required in the 50-90 kVp range. 8 to 9
A ___ to __ percent change in kVp is required in the 90 - 130 kVp range. 10 to 12
The 15 percent rule is somewhat accurate within the range of ___ to ____ kVp. 60 to 100
The image receptor exposure is always greater at the _________ end. Cathode
The anode heel effect is also more significant when using ____ _____ anodes (12 degrees or less) small angle
The portion of an object with the greatest subject density should be placed toward the ____ end of the tube. Cathode
Radiolucent contrast media (air) will _________ film density. Increase
Radiopaque contrast media (barium, iodine) will _______ film density. Decrease
As relative speed increases, the amount of exposure required to maintain the same film density ____________. Decreases
Film density will _____ when developer solution temperatures ________. Increase, increase
Film density will _____ when developer solution temperatures ________. Decrease, decrease
__________ ____________ controls image contrast. Window width
As the slope of the Dlog E curve increases, contrast is _______. Increased
Low kVp produces ____ subject contrast because most of the low energy photons are absorbed by thicker parts. Higher
With high kVP, subject contrast is _______ because more uniform penetration occurs between thick and thin parts. Decreased
In a fixed kilovoltage system, the kVp is held _______, while the mAs is ______ to achieve appropriate image receptor exposure. Constant, varied
Fixed kilovotage technique systems, _____ patient dose. Decrease
_______________ kVp is the maximum kVp level that will produce images with appropriate contrast, consist within acceptance limits. Optimal
The objective of optimal kVp is to determine the ____kVp and _____ contrast that is within acceptance limits. Highest, lowest
A ________ ____________ x-ray exposure technique system is one where the kilovoltage to be used for a particular projection is varied, depending on measured body part thickness. Variable kilovoltage
Created by: rad1958tech on 2008-11-08



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