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Ch17 & 18 Bushong
Terms in this set (88)
1. What are the two principle characteristics of a medical image?
spatial resolution & contrast resolution
2. What is spatial frequency?
Describes the quantity of spatial resolution, measured in lp/mm
3. As we increase spatial frequency, what happens to the object size?
It becomes smaller
4. What if the MTF (modulation transfer function) were 1, what does that mean?
Perfect 100% everything we received was recordednot possible
5. What do we call how many shades of gray an imaging system has
Gray scale, dynamic range, bit depth
6. What does screen film have as a dynamic range?
3 decades 1,000 shades of grey
7. What digital system has the highest dynamic range?
8. Spatial frequency & spatial resolution has what % of MFT
9. Which of the following is responsible for bright light, colors, & are photopic?
10. The science of what, is the study of the response of the human eye?
11. An LCD is a material in a?
a state both liquid and a solid
12. What are the 4 principle components of a PAC's system?
Image acquisition display, network, and storage
13. What does PAC's stand for?
Picture Archiving & Communication System
14. What does DQE (Detective Quantum Efficiency) measure?
Amount of x-rays that are absorbed
15. What is a RIS?
Radiology Information System
16. Objects with high spatial frequency are harder or easier to image?
17. If you had a perfect system what would MTF be?
18. How many shades of gray can we image w/our eye?
19. What is the basic photometric unit?
20. Preprocessing is done automatic or manually?
21. Should you ever repeat digital image for contrast, brightness, or overexposure?
22. What is spatial resolution in DR limited by
23. Almost all digital images in Medical Imaging are viewed in and interpreted on a?
Digital Display device
24. What is the ability of the yet to see black and white images?
25. Where do you find the rods of the eye in the greatest concentration?
Periphery of the retina
26. When looking at a digital display monitor, where is the best place to view them?
With a high frequency what can you image?
Breast tissue need a lot of high resolution, low contrast.. if it was low frequency... hip..
What is Modulation Transfer Function (MTF)?
The ratio of image to object as a function of spatial resolution
How many decades does film have? Digital?
3 on film, 4 on digital
What is a 16-bit dynamic range?
2^16= 65,536 shades of gray
Signal to noise ratio dealt with?
Contrast resolution, we want the best signal with as low as possible noise. You want high signal to noise
What is contrast resolution limited by?
What is "Dose creep"?
With digital we will always yield a good image, going from a lateral to anterioposterior view and not changing factors it's possible to increase patient dose
What is modulation transfer function for?
9. What happens to contrast at low spatial frequency?
The contrast of the object is preserved
10.What happens to contrast at high spatial frequency?
Contrast is lost at high spatial frequency
11. What is contrast resolution?
The ability to distinguish many shades of gray from black to white
12. Which of the four: luminous flux, illuminance, luminance intensity, luminance, describes luminence intensity from a light source such as a light bulb?
13. What is the portion of useful image forming x-rays? What do we refer to that as? Frequency? MTF? Signal? Noise?
14. Studies have shown that breast tissue is best imaged with... screen film? Digital? Cerography? CT. Why is that?
Digital. We found out that spatial resolution was not as important as contrast resolution.
15. As we increase mAs what happens to the signal?
Increases, goes up
16. What's another word for image detail?
17. Which has the best contrast of imaging systems?
18. What does DQE stand for
Detective Quantum efficiency
19. What does MTF stand for?
Modulation Transfer Function
20. If you had an image receptor with a high DQE what will that do to patient dose?
It will lower it
21. The higher the spatial frequency the better the spatial resolution, True or False?
22. What is windowing and leveling?
Expand the digital gray scale to visible
23. With the new data we have should doses in digital radiography be lower or higher because of high DQE?
24. What is responsible for high visual acuity?
25. Digital display device with higher megapixels has higher spatial resolution, True or false?
True, more is better
26. The flat panel displays that radiologist look at... what are they?
27. What does DICOM stand for
Digital imaging and communications in Medicine, standard imaging & interface format
28. Decreasing luminous intensity with increasing distance follows which law
Inverse square law
1. What is spatial resolution?
(resolution in space) ability of an imaging system to resolve and render on the image a small high-contrast object.
2. If I have high spatial frequency, what is spatial resolution going to be like?
Resolution will be better
. (Big dots) What kind of system do we need to visualize the tiny dot
We would need high spatial frequency
4. What is the unit used to measure spatial frequency?
Line pair per millimeter (lp/mm)
5. Which system has the highest spatial frequency?
6. What is the spatial resolution for mammography?
7. Define Modulation Transfer Function (MTF):
How much information is available and how much information is recorded (how well it records and captures it
9. What is dynamic range?
13. The useful x-rays that are coming out of the patient, what do we call that in terms of digital?
10. What determines the number of shades of gray?
number of bits
11. What is 8 bits in terms of a byte?
12. What is the quantum mottle portion called?
13. How can we increase the signal?
14. True/False: Contrast resolution is limited by signal-to-noise ratio?
15. In screen-film, what is spatial resolution determined by
16. In digital, should we repeat an image for overexposure
17. Should we be able to save patient dose in digital?
18. True/False: Detective Quantum Efficiency (DQE) is the measure of x-ray absorption efficiency.
19. What are the two things that give vision to us in our eyes
Rods & Cones
20. Rods are good for
dim light, black/white, and are scotopic
21. Where do you find the cones?
22. Luminous flux:
total intensity of light from a source
intensity of light incident on a surface
24. Luminance intensity
property of the source of light, such as a viewbox or a digital display
another measure of the brightness of a source such as a digital display device expressed as units of candela per square meter or nit
26. Cosine law
describes the luminous intensity of a digital display device (better to view straight on)
27. What is hard copy?
images on film
28. What is soft copy?
digital medical image
29. What is better, an old CRT cathode ray tube or an LCD?
30. Figure out a matrix. example 10 x 10
31. How much of backlight is transmitted through a monochrome?
32. How much of backlight is transmitted through a color?
33. What is aperature ratio?
aperature ratio is to a digital display device as "fill factor" is to a digital radiographic detector. Aperature ratios of 50% to 80% are characteristic of medical AMLCDs.
What is ambient light?
The systems accuracy in placing reflectors at correct depths located parallel to the sound beam
Contains data about a patient and has been documented by the professionals who provided care to the patient.
If you had to choose between having a high level of business acumen or being an expert statistician, which choice would provide more value to your company and why?
The purpose of a garbage mask is to remove all of the green or blue screen from the foreground.
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