Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Radiology Vcast05 > physic chapters 20-22 > Flashcards

physic chapters 20-22 Flashcards

1
Q

what is a histogram

A

a graphic rep. of exposure received to the pixel elements and the likelihood of those exposures within the image inside the collimated area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what should be checked on the menu before exposing a patient

A

check for correct anatomic region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is compared to the raw data histogram?

A

a normal histogram with the same anatomical part

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

values of interest (VOI)

A

the range of histogram data set that should be included in the displayed image. (contrast would be too low if all shades were left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

the less the exposure to the receptor what is created on the histogram

A

light color

ex. the spin denser than the lung tissue so that is why the spin appears white and the lungs appear dark

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what type of range does digital radiography allow

A

wide dynamic range

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is dynamic range?

A

it is a leaner relationship between exposure and the resulting pixel value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are some problems with a wide dynamic range

A

too low of an exposure can result in noise

too high of an exposure leads to high patient exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how does a high S number correlate with exposure and how does low S number correlate with exposure and S number?

A

low exposure= high S#

high exposure= low S#

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what causes blurring in a digital image

A

FSS, motion, receptor (light spread from the screen phosphors), and pixel size which is the ratio of the FOV (field of view) snd the matrix size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are the Y and X axis of a histogram

A

Y axis= # of pixels and X= VOI (values of interest; pixel value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is a histogram analysis error

A

in CR the entier imaging plate is scanned to extract the image from the PSP. (if at least three edges are not identified, a histogram error could occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is a look up table (LUT)

A

is a reference histogram which maps the grayscale values

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how are LUT values graphed

A

original values on the X- axis and the new values on the y-axis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how can the LUT graph control contrast (what aspect of the graph)

A

contrast can be increased or decreased by changing the slope of its graph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how can LUT control density

A

brightness is controlled by increasing or decrease moving the line up or down the Y-axis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how does the LUT image contrast transfer function work

A

basically the original image is altered which leads to diff. pixel values then the final image is processed, causing diff. contrast levels.
(this is the reason why we can have a wide dynamic range)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

digital annotations

A

manual text and preset terms (EX. FLEXION AND EXTENSION, PORTABLE/UPRIGHT)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

should you use digital annotations to identify patients Lt. or Rt. side?

A

no

20
Q

in digital CR what happens during Quantization by the ADC

A

each pixel represents a gray shade that is given a number value that controls the shades of gray

21
Q

what is pixel depth ?

A

determines brightness level available for image display

(fixed in the system by the ADC

22
Q

what happens when you increase pixel depth in regards to contrast resolution

A

increased contrast resolution

23
Q

what is image stitching?

A

is a computer process that allows images to be joined when the anatomy is too large for one exposure

24
Q

what should be used during a scoliosis series?

A

image stitching

25
Q

what is smoothing?

A

filters out high frequency noise
( does this when frequency in each pixel is averaged with surrounding pixel values)
reduction of noise and contrast

26
Q

what is another name for smoothing

A

low-pass filtering

27
Q

what is edge enhancement (cath)

A

average of signal to shorten processing time and storage

28
Q

what is high-pass filtrations definition? (Cath)

A

averaging of the signal to shorten processing time and storage

29
Q

what is another term for high-pass filtration? (Cath)

A

edge enhancement

30
Q

what contrast does edge enhancement provide (Cath)

A

allows the visibility of high contrast structures

31
Q

veil glare

A

unexposed borders around the collimation edges allow excess light to enter the eye

32
Q

what chemical that is over-sensitized causes glare/white light blinding

A

rhodopsin

33
Q

shuttering

A

blocking the light coming from the unexposed area (which is white and causes vail glare)

34
Q

when does Automatic rescaling occur

A

this occurs to display the pixels for the area of interest (zooming).
resizing of the image matrix

35
Q

when rescaling what are some problems that occur when we have an underexposed image

A

this results in quantum mottle

36
Q

when rescaling what are some problems that occur when we have an overexposed image

A

loss of contrast and loss of distinct edges b/c of + scatter production

37
Q

what kind of images are produced when automatic rescaling occurs

A

images with uniform density and contrast regardless of amount of exposure

38
Q

what is QC

A

anything that deals with instrumental/ equipment

39
Q

what are types of QC

A

tools used to measure EI, AEC calibration, image plate cleaning, Alignment and collimation test tool, focal spot size, kVp calibration, timer, linearity, reproducibility

40
Q

QC in relation to Alignment and collimation test tool

A

indicators within 2% of SID and centering within 1% of SID

41
Q

QC in relation to Focal spot size (diff. tests)

A

Pinhole camera; star pattern and slit camera

42
Q

QC kVp calibration would be within ______%

A

kVp within 10% of the indicted kVp

43
Q

QC Exposure Timer should be within ____% for exposure times greater than______

A

within 5% of the indicated time for exposure times greater than 10 ms

44
Q

QC Linearity should be within _____%

A

accuracy should be within +/- 10%

45
Q

QC reproducibility should be within______%

A

sequential radiation exposures (at least 3) should be within +/- 5%

46
Q

how does the cathode ray tube work in the digital monitor?

A

accelerates and focuses electrons to strike the flat plate of fluorescent screen
(scans the screen in lines affecting image quality)

47
Q

how does the Liquid crystal display work?

A

passes light through liquid crystals displaying image on the glass faceplate
-electrical signals and light waveforms vary as they pass through the crystals for viewing on the faceplate

Radiology Vcast05 (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions