Final Review Flashcards
Degradation of an image in CR can occur if:
- exposed IP is not processed soon after exposure
- exposed IP has been exposed to high enough temperatures
Which portion of the IP records the CR image?
Photostimulable phosphor
Factors that influence the emission spectrum are:
mAs, kVp, Z, voltage ripple, added filtration
Two exposures are taken. Exposure 1 is taken with an 8:1 grid, and exposure 2 with no grid. How would the patient dose and radiographic density be affected for exposure 2?
No effect on patient dose, increased radiographic density
The most common cause of tube failure is?
Vaporization
In an x-ray exposure, the majority of the x-rays in the primary beam are?
Bremsstrahlung
A patient presents with a pathology that reduces the mass density of their tissue, resulting in decreased beam attenuation. What can this pathology be classified as, and how should technique be adjusted?
Destructive, decrease technique
A chest x-ray was taken using AEC and the center cell was selected. Predict the appearance of the image
-spine would have optimum density
If a grid was placed with the grid lines transversely on the table and the tube was angled 15 degrees cephalad, what grid error would occur?
Off level
Which factors when decreased will increase radiographic density?
- grid ratio
- part thickness
If an image is determined as “too light” the mAs should be increased by
Double it (x2)
What is an example of a situation where you would utilize a technique chart instead of using AEC?
- pregnant
- finger x-ray
- post op hip patient
Radiographic contrast is influenced by?
- differential tissue absorption
- matrix characteristics
In which part of the circuit is the step down transformer located?
Filament side
When comparing film/screen to digital imaging an advantage of digital imaging is?
Improved contrast resolution
Quantum mottle can be decreased by?
-decrease kV, use higher mA
Which of the following is the geometric characteristic of a computerized image?
Spatial resolution
Heat units formula:
HU=kVp x mA x time x modification factor
Total filtration in beam
Equals added and inherent filtration
Histogram
Graphical representation of all the densities on the image, raw data of image
what is an acceptable repeat rate?
5%
An artifact caused by backscatter would look like?
Dark lines
What happens to the mAs when the exposure time is halved?
It is halved
After substantially increasing collimation, what should be done to the technical factors to maintain density?
-mAs should be increased
When changing the visibility of an image by using the LUT what is being altered?
Pixel value
Recorded detail is defined as?
The accuracy of structural lines recorded
Shape distortion will result from?
Angling the central ray
______ is the ability of an imaging system to distinguish between adjacent structures
Resolution
The relationship between focal spot size and distance is?
Geometric unsharpness
An exposure is taken with a stationary high ratio grid. The resultant image shows extreme loss of density on the side of the image. What grid error has occurred?
Off center
What has the most detrimental effect on recorded detail?
Motion
As collimation increases (making light smaller), ____ increases
Contrast
An image that requires little or no post processing can be described as?
Diagnostic
An image described as having many shades of grey is _____ contrast
Low contrast
The equivalent effect on density of doubling the mAs is?
Increasing the kVp 15%
