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kortney21
on FreezingBlue Flashcards.
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What is the primary function of the milliampere-seconds during a radiographic exposure?
The regulation of the optical density in the image
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The amount of darkening from the black metallic silver deposited in the film is termed?
optical density
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What radiographic image that is likely to show the highest optical density?
Gas
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The greatest amount of attenuation occurs in what corresponding tissue?
bone
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the primary exposure factor that is used for regulating radiographic contrast is
Kilovoltage peak
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when a barium-type contrast agent is employed, the desired degree of penetration can be accomplished by using what kilovoltage setting
90-110kvp
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a radiographic image is said to possess excessine optical density; this image would appear to be what?
Darker than normal
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A reduction of scattered radiation on a radiographic image is likely to occur with a/an?
increased collimation
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An increase of 15% in kilovoltage will necessitate a?
50% decrease in the mAs to maintain the same optical density
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What pathological change in a patient is likely to require an increase in penetration to maintain the desired optical density?
pulmonary effusion & acromegaly
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An abdominal radiographic is taken of a pt measuring 21cm. If all the same conditions are maintained & a second image is taken on a different pt measuring 29 cm, the image will have? (3 things)
- 1. reduced optical density
- 2.reduced radiographic contrast
- 3.reduced spatial resolution
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The dose a pt recieves during a diagnostic exposure is directly proportional to the?
mAs employed
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A decrease in the amount of scatter produced in a tissue will occur as?
kilovoltage peak setting is decreased
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Which of the primary exposure factors has the greatest affect on beam quality, attenuation, & exposure latitude?
kilovoltage peak setting
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A radiographic image is produced with insufficient contrast & excessive optical density. Which of the following changes in the exposure factors will best correct for this error?
Decrease the mAs and KVp
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An increase in the exposure factors to maintain the desired optical density is often required for pts with?
hydrothorax
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An increase in the number of xray photons reaching the image receptor is normally associated with?
increased optical density
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Which of the following tissues will have the lowest absorption coefficient to xray photons in the 50-120kvp range?
free air or gas
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As the wavelengths of the photons in an xray beam are increased the.....
beam penetration decreases
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Radiographic contrast can be defined as the?
difference in the optical densities between adjacent areas of the radiograph
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The kilovoltage peak setting is most closely related to the?
radiographic contrast of the image and penetration of the beam
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Many skeletal disorders will require an increase in technique due to an overgrowth in bone tissue. These are referred to as?
osteoblastic conditions
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An example of a pathological change in a pt that will require an increase of penetration to maintain the desired image quality is?
- 1. pneumoconiosis
- 2.Empyema
- 3. Ascites
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A radiographic image is produced using 20 mAs and 74 KVp. Which of the following are likely to occur on a second image taken with 15% increase in the kVp value?
The radiographic contrast of the first image will exceed that of the second
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The milliamperage-seconds value employed during an xray exposure is directly proportional to?
the quantity of xrays produced in the exposure
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A radiographic image is produced of a high tissue density structure. The area of the radiographic image corresponding to this structure will show a?
low optical density
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A radiograph that shows a short scale contast often results from the use of?
low kilovoltage techniques
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Which of the following sets of technical factors will result in a radiographic image with the least amount of involuntary motion?
~mA Time kVp
200 100ms 80
400 .05sec 80
800 .03sec 80
800 75ms 70
800 .03sec. 80
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The utilization of high kVp (above 90 kVp) for radiographs of the abdomen will result in?
High exposure latitude and long scale contrast
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When a fixed kVp technique chart is employed for the selection of exposure factors what is the expected result from underestimating the physical density of tissue in the patient?
A radiographic image with an insufficient optical density
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The appropriate degree of penetration for a small body part (finger-hand) is normally accomplished by using a kilovoltage setting in the range of?
55-65kVp
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Which of the following is likely to occur if kilovoltage is increased for a radiographic exposure?
- 1. Increased optical density
- 2. Longer scale contrast
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A beam with a low penetrability is often referred to as a soft beam or?
Low quality beam
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Which of the following substances possesses the highest degree of radiopacity?
Lead
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A radiographic image produced showing a small degree differential attenuation, is best described as having a?
Low radiographic contrast
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In order to see a noticeable change in the optical density, a change of _______ in the mAs is required?
30%
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A radiographic image of a child has been obtained using 100 mA 20ms at 74 kVp, but due to movement, the radiographic image is unacceptable. In order to reduce motion, a 60% reduction in time is desired. What new timer setting should be employed?
8ms
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What is the primary function of the milliamperage-seconds during a radiographic exposure?
The regulation of the optical density in the image
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Window level controls?
how light or dark an image
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Window width?
controls the ratio of black to white or contrast
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Electronic memory artifact occurs when exposures are taken in to rapid of a sequence. T or F?
true
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Thin film transitor is?
- ~thin layer of transistors on a sub
- ~will detect either light or electrons
~a transistor will be located @ each pixel can be smaller and can be switched on & off more quickly
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Amorphous silicon detector uses?
thin films of silicon integrated with arrays of photodiodes
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Direct Capture detectors consists of?
a photoconductor (amorphous selenium (A- Se))
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When scintillators are struck by x-rays, what happens?
visible light is emitted proportional to the incident x-ray energy
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The scintillation layer in the imaging plate is excited by?
x-ray photons & the scintillator reacts by producing visible light
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Direct Conversion DR TFT?
a million-plus pixels can be read & converted to a composite digital imaging in less then 1 sec
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The Nyquist theorem states that the sampling frequency must be twice the input signal bandwidth? T or F?
False; greater tan twice the bandwidth
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