Exam 1: Technique Evaluation Flashcards
Determines the penetrating power of the x-ray?
Kilovoltage (kVp)
Determines the total number of x-rays and the time they can be released from the x-ray tube to expose the film?
Milliamperage-second (mAs)
The degree of blackness of the radiograph?
Radiograph density
The difference in density between two areas on the radiograph?
Radiographic contrast
____ affects the density?
mAs
If an area is very dense fewer x-rays will pass through, therefore the object will appear _____ on the image.
Lighter
____ and ____ density are inversely related.
Tissue and film
From whitest to darkest:
Metal, bone, water, fat, gas
Film fogging due to improper storage, processing conditions, and light exposure can also effect the ____?
Density
If there is a lot of variance between density of the radiograph, the contrast is said to be ____?
High (basically black and white)
Slight difference in density results in ___ contrast?
Low (more areas of grey)
____ affects the contrast?
kVp
We refer to low contrast (more areas of grey) as a _____ scale of contrast?
Longer
As kVp increases, the scale of contrast _____?
Increases
Things that can effect contrast:
- Tissue density
- kVp
- Object shape and density
- Film fogging
- Use of contrast medium
Radiographs should be viewed in a _____ room using an ____ lit view-box.
Semi-darkened; evenly
How should a radiograph be placed on the view-box?
-Animal’s head should be at the top
-Animal’s right should be to the viewer’s left
For lateral views, the animal should face the left and their spine should face the top of the view-box.
Two main questions of the technique evaluation:
- Is the radiograph too dark or too light?
2. Does it show proper penetration?
The more the exposure, the _____ the film.
Darker
Underexposed radiographs will appear too ____.
Light
General rule of overexposed radiographs (too dark)
Decrease the kVp by 10 or half the mAs.
General rule of underexposed radiographs (too light)
Increase the kVp by 10 or double the mAs.
To determine whether to adjust the kVp or the mAs, you must first decide if the radiograph has?
Proper penetration
If penetration is inappropriate, you adjust the ___ how?
kVp
Too light- increase
Too dark- decrease
If the penetration is satisfactory, you adjust the ___ how?
mAs
Too light (bright)- increase
Too dark- decrease
When looking at a radiograph that appears too light: How do you know if x-ray penetration is adequate?
The anatomical outlines should be visible.
ex. when viewing the abdomen the outline of the liver, spleen, kidneys, etc should be visible.
When viewing a radiograph that appears too dark: How do you know if the x-ray penetration was too much?
Look at the contrast between the radiographic images.
ex. bone tissue compared to soft tissue
General rule for radiographs that are too dark:
High kVp results in an increased contrast scale (radiograph appears grey)
You want to have low contrast/ longer contrast scale in radiographs of ____ tissue such as the abdomen.
Soft
You want to have high contrast/ shorter contrast scale for radiographs of ____?
Bone
Name some disease factors or other factors that could effect the radiograph machine settings:
- Pleural fluid/effusion
- Ascites
- Obesity
- Plaster cast
- Younger animals
An area of un-sharpness on the image
Peumbra
Artifact that is caused by the divergence of the beam
Peumbra
Artifact where the small area under the small social spot will be clear, but other areas of the film may be blurred.
Peumbra
Artifacts where the heel of the anode absorbs some of the electrons that are emitted; therefore the images on the cathode side of the radiograph may not be as sharp.
Anode-heel effect
Appears as an overall greenness in the film causing a decrease in contrast.
Film fogging
Artifact that usually results from improper storage of the film resulting in damage from ambient light and/or scatter radiation?
Film fogging
Artifact where the image will appear larger than normal
Magnification
This occurs when the portion of the animal that is being radiographed does not remain parallel to the film. The object either appears elongated or foreshortened.
Distortion
Can cause a blurred appearance of the film. It can also reduce the amount of contrast seen on the film.
Movement
To reduce movement, use the _____ time setting possible.
Shortest
