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54 Cards in this Set
- Front
- Back
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What are the two principle characteristics of an image? |
Spatial resolution and contrast |
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What is spatial frequency ? |
It refers to line pair per millimeter |
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What is resolution limited by in digital? |
Pixel size |
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What is needed to see a small object? |
High spatial resolution |
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What does MTF stand for and what is it? |
Modulation Transfer Function-function of measuring the imaging system (image small objects) |
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Can you ever have more information recorded than available? |
No |
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A perfect system would be what number? |
1 |
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What is luminous flux? |
Total intensity of light from a source such as a light bulb |
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Define illuminance. |
Describes the intensity of light incident on a surface. |
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What is luminance intensity? |
Property of the source of light such as a digital display device |
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What is luminance? |
Another measure of the brightness of a source |
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How many shades of gray can a person visualize? |
30 |
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What is dynamic range? |
The shades of gray |
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What is the main backlight for a monitor? |
LED |
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Why is LED better? |
Less heat , less expensive , more convenient |
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What is bit capacity/depth identified? |
The gray scale |
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Out of all the imaging modalities which one uses the most storage? |
Digital mammography |
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Which modality has the highest dynamic range? |
Digital mammography |
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What happens to the signal to noise ratio when mAs is increased? |
It gets better , increases the signal |
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What is signal? |
X-rays that come out of the patient |
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Out of all modalities which one has the best contrast? |
CT |
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To reduce patient dose what can be done? |
Increase kVp |
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What is DQE? |
Detective quantum efficiency — how well it’s receiving Photons |
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If one image receptor detects more Photons than another what does that mean? |
It has a higher DQE |
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What does high DQE mean for patient dose? |
Lowers the dose |
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What are rods used for? |
Can see black and white vision darkness — |
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What are cones responsible for? |
Color and bright light |
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What is vision acuity? |
Ability to see detail |
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How do you stimulate an LED? |
With electricity |
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What does LED stand for? |
Light emitting diode |
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What is photometry? |
The science of the response of the human eye to visible light |
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What is the basic unit of photometric? |
Lumen |
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What is inverse square law? |
Luminous intensity decreasing in proportion to the inverse square of the distance from the source |
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What is the cosine law? |
Describes the luminous intensity of a digital display device |
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Where’s the best place to sit when viewing a monitor ? |
Straight on — in front |
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What is a LCD stand for? |
Liquid crystal display |
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What is an LCD? |
A liquid crystal is a material state between that of a liquid and a solid |
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What does phosphorescence mean? |
Light emission following stimulation —keeps glowing after |
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What does fluorescence mean? |
Light emission during stimulation |
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If you have high mega pixels you will also have what? |
better Resolution |
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All flat panel digital displays have color or not? |
No their Monochrome |
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What does PACS stand for? |
A picture archiving and communication system |
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What does DICOM stand for? |
Digital imaging and communications in medicine |
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What is DQE a measure of? |
X-ray absorption efficiency |
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What is RIS? |
Radiology information system |
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What are the four components of a PACS? |
Image acquisition system, display system, network, and storage system |
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What is HIS? |
Hospital information system |
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Where are rods located? |
On the sides of your eyes and responsible for peripheral vision |
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Where are cones located at? |
Right at the back of the eye |
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What does window and level do? |
Expand the digital grayscale to visible |
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What is pixel shift? |
Reregister an image to correct for patient motion |
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What is subtraction (DSA)? |
Improve image contrast |
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Define region of interest. |
Determine average pixel value for use in quantitive imaging |
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What part of the eye is responsible for high visual acuity? |
The cones |
