IP
The more pixels sampled per millimeter, the __________?
the greater the sampling frequency
what is contrast resolution?
ability to detect subtle differences in gray scales
what is quantum noise?
1. quantum mottle or contrast loss. results when too few x-ray photons reach the IR.
2. UNDEREXPOSURE
what is:
the ability of a system to both overexpose and underexpose, yet still produce an acceptable image . this is the range within the dynamic range.
exposure latitude
An increased signal= ____________?
an increase in visibility of spatial resolution
What type of radiography uses sampling frequency?
CR
what results from x-ray deposition of energy in a detector? (image data)
signal
How does increased intensity affect noise?
decreases noise.
what is signal to noise ratio (SNR)?
ratio between "signal" or meaningful information and "noise" or background information.
What does noise decrease?
our ability to see all spatial resolution and contrast resolution on the image.
increasing the sampling frequency result in the ____________?
the laser moving a smaller distance, and there is an increase in spatial resolution.
what is dynamic range?
range of values over which a digital image receptor will respond. (contrast resolution)
how does decreased intensity affect noise?
increases noise.
what happens as noise increases?
it becomes more difficult to visualize small objects.
why is proper image identification important?
radiographs are considered legal documents of patient information.
What is Nyquist Frequency?
relationship between sampling frequency (number of pixels scanned by the laser) and spatial resolution (image detail/sharpness).
Greater dynamic range will yield ______?
greater contrast resolution.
what are the three types of noise?
1. quantum noise/quantum mottle
2. scatter
3. electronic.
Is it more desirable to have a low SNR or a high SNR?
high SNR
What information MUST be included on a radiograph?
1. patient data (name and ID number)
2. exam data (postural and side markers).
3. date exam was performed
4. institutional data (hospital name where exam was performed)
what is the minimum rate at which a signal and be sampled, without introducing errors?
2 times the highest frequency present.
What is:
results from extaneous information (interference), limits the ability to visualize objects.
noise
what is:
series of exposure values used to produce an acceptable image. lightest lights to the darkest darks, than can be seen.
dynamic range
Noise impacts ___________?
perceptibility of spatial resoltuion
What is the minimum change in mAs, to make a noticeable difference on your image.
30%