Quiz 1 Flashcards
1
Q
Which scans measure anatomical structures mostly?
A
X-rays, CT scans and MRI
2
Q
Which scans are used to measure function?
A
PET, SPECT, fMRI
3
Q
spot=
A
pixel
4
Q
shades are coded by
A
number
5
Q
white code?
A
256
6
Q
black code?
A
0
7
Q
1 bit gray scale images have
A
2 options: 0, or 1
8
Q
2 bit gray scale images have
A
4 options
9
Q
in gray scale when we increase the number of options its called…
A
bit resolution
10
Q
when we increase the number of pixels in gray scale resolution its called…
A
spatial resolution
11
Q
bit and spatial resolution is associated with…
A
file size
12
Q
RGB color code is usually in what format?
A
XX (Red) XX (green) XX (blue) FF thrown in there too for increased saturation
13
Q
gray scale is what combination of the three colors?
A
equal intensity
14
Q
example of coding for saturated red?
A
FF0000
15
Q
Example of coding for saturated green?
A
00FF00
16
Q
example of coding for saturated blue?
A
0000FF
17
Q
example for grey scale?
A
454545 or 999999 (Anything repeating)
18
Q
In CMY coding, what is used for black?
A
K
19
Q
numbering systems used to code that were talked about?
A
TIFF and JPEG
20
Q
Other systems that are completely different?
A
JAVA and Matlab
21
Q
What does noise equate to in images?
A
differences in pixels that are not related to anatomy or physiology
22
Q
What can reduce noise?
A
filters
23
Q
How do we get texture in images?
A
photographers use shadows. But texture can be created by organization of pixel grayscale
24
Q
texture can look …or…
A
fine or course
25
fine texture comes from ...pixels and course texture comes from ...pixels
small
| large
26
What are the steps in texture analysis?
1. measure range or difference between max and min intensity of neighboring pixels. the brighter the area, the more texture.
2. texture segmentation-give an outline
3. variance-calculate the sum of the square of differences in intensity between neighbors
27
step two in texture analysis: texture segmentation?
boundaries between textures analyzed (to give outline)
28
step three in texture analysis: variance?
calculate the sum of the squares of differences in intensity between neighbors.
29
smoothing can also be called...
blurring.
30
smoothing looks at the color or grayscale and ....
averages to nearby
31
edge detection is...
an automated way to detect changes in tissue (or a discontinuity in the intensity or pattern of pixels)
32
3 kinds of edge detection?
step edges, line edges, ramp edges
33
step edges
detects sudden change from one value to another
34
line edges
abrupt change, but then returns to previous
35
ramp edges
gradual changes
36
edge enhancement can help how clinically?
volume of blood in the heart at the end of diastole or systole
37
shape analysis gives us what?
a region of interest (ROI)
38
What is registration?
process of bringing 2 or more images into spatial correlation or matching.
39
What is intermodal registration?
using images from different imaging techniques (MRI+CT)
40
in registration the .... between different structures is transformed to match.
spatial relationship
41
registration allows following
the patient over time (like annual mammograms or tumor prognosis)
42
What are two types of registration errors?
point-based, target
43
When were X-rays first discovered/used? and by whom?
late 1880s; wilhelm roentgen
44
What did Wilhelm use to discover X-ray capability?
ran an electrical current through a glass tube and saw a faint green light
45
What did he do after his initial light picture?
put a vacuum in the tube and the light increased
46
Why did he name it X-ray?
it meant there was light coming from somewhere unknown and it was meant to be changed and wasnt.
47
earliest xrays were produced with
gas tubes
48
in the earliest xrays, penetration was dependent on? Intensity was dependent on?
voltage
| current.
49
in the earliest xrays if they reduced gas pressure what happened? What did they do to eliminate the problem?
the current fell and they would lose clarity of the picture. tungsten filament in the 1900s
50
What 2 things make xrays different?
1. they can penetrate matter
| 2. they ionize gasses which is how xrays are created.
51
xrays were originally made in...Why?
a tube; electrons move more quickly in the tube and hit the tungsten.
52
the xrays in the tube released a ... called...
photon; Bremsstrahlung radiation
53
not all electrons that hit the tungsten will produce photons, most lose .... so tungsten must be able to withstand high heat and ...the heat away from the tube.
energy producing heat; conduct
54
xrays are considered ....
electron accelerators
55
penetration of xrays are dependent on the ..... at which the electrons hit the target.
speed
56
speed of electrons is dependent on ....across tube.
voltage
57
absorbed photons in the body ....usually a .... in the body.
bind to something; receptor (accepter molecule)
58
reflected photons ...
do not enter the body
59
transmitted photons...
pass directly through material
60
refracted photons ...
travel through, but the angle is altered
61
3 tissues easiest to differentiate in x rays
bone, lungs, soft tissue
62
bone=
high absorption
63
lungs=
low absorption
64
soft tissue=
middle
65
xrays are the chosen method for...
bone fractures
66
xrays have better ...than MRI or ultrasound
spatial resolution
67
xray film is called
radiograph
68
as photons hit the film it turns...
dark
69
the more dense the material (more absorption) the ...
lighter the film
70
xrays can cause damage to cells that are coded for being cancerous. energy will bounce from once cell to another causing damage, this is called
ionization
71
....is most sensitive to ionization
DNA
72
body is able to repair most damage by ....
apoptosis
73
xrays are ...risk than other imaging techniques
higher
74
single chest xray is ...% of radiation for a year
20%
75
CT developed in
1917
76
first CT equipment used in...
1970s
77
used ... for CT scans like early xrays. now they are ....components
gas tubes; solid state
78
CTs are ....of different Xray slices that could be looked at from different angles.
registration
79
today, rotating xray beam collects...
emitted electrons
80
single image in the entire series is called
comograph
81
CAT
computed axial tomography
82
in CT beam can be sent out as ...or...
fan or parallel
83
typically the xray beam in a CT must rotate ....degrees to get the best images. in fan mode it needs... degrees.
360; 180
84
beam in a CT hits ...
more than 1 detector at a time
85
kernels are
filters for 3D; they typically sharpen or blur the image
86
CT data has more ...than xray and high pass filter increases it.
noise
87
two types of reconstruction?
analytical, iterative
88
analytical reconstruction uses...
algorithms based on anatomical points
89
iterative reconstruction uses...
assumption and compare to assumptions with measured data and it continue to makes adjustments
90
compared to xrays, CT slices are ....
very thin so radiation is lower
91
newer generations of scanners perform ...
very low dose scans with more sensitive detectors and faster rotator speeds.
