RAD SCI FINAL Flashcards
(159 cards)
1
Q
what is CPU?
A
central processing unit
coordinates all computer operations
2
Q
what is the RAM?
A
random access memory
can be overwritten by the user and accessed very quickly
memory stored on a chip or disc
3
Q
what is ROM?
A
read-only memory
memory that can’t be changed by user
(foundational programs)
4
Q
what is BIOS?
A
basic input/output system
internal/primary ROM that directs the flow of information between CPU & peripherals
5
Q
what is the motherboard?
A
houses CPU, RAM, ROM chips and connections for USB/audio
6
Q
what is LAN?
A
Local area network
a network contained within a single building or business
6
Q
what is WAN?
A
wide area network
extends to multiple businesses or geographical areas
7
Q
Bit units are used for:
A
binary numbers
7
Q
what is a bit?
how many bits become a byte?
A
small unit for binary numbers
8 bits
8
Q
what is teleradiology?
A
remote transmission of medical images via telephone wire or fiber cable outside a facility to a radiologists home or remote radiologist on the other side of the world
9
Q
convert this binary code: 110011
A
51
10
Q
what is the smallest unit of a digital image?
A
pixel
11
Q
the smaller the pixel:
A
the better the spatial resolution
12
Q
in diagnostic imaging pixel size is limited by:
A
detector element size (DEL)
13
Q
what is the field of view? (FOV)
A
the physical area of an image
14
Q
what is the matrix?
15 x 15?
A
a pattern of pixels laid out in rows and columns
225
14
Q
what is bit depth?
A
maximum range of pixel values that a computer can measure or store
14
Q
what is scanning?
what is sampling?
what is quantization?
A
creating a matrix
measuring the intensity
assigning a value
15
Q
what is a bit depth of 5?
A
32 shades of gray
(human eye can distinguish between 32 shades)
16
Q
what is a bit depth of 8?
A
256 shades of gray
common for non-medical imaging
17
Q
what is the bit depth 10?
A
1024 shades of gray
number of shade of gray in the remnant beam
18
Q
what is dynamic range?
A
the range of shades of gray that a system can generate
(diagnostic is large)
19
Q
what is window leveling?
A
adjusting the image brightness
increasing the window level decreases the brightness
decreasing the window level increases the brightness
20
Q
what is window width?
A
adjusting the images contrast
increasing the width increases the shade of grey in the image (low contrast)
decreasing the width decreases the shade of greys in the image (high contrast)
21
what is the greatest benefit of digital imaging?
the ability to control contrast resolutions
22
what is the image matrix of these modalities?
Nuc med:
US:
MR:
CT:
x-ray:
Mammo:
64 x 64
128 x 128
512 x 512
512 x 512
1024 x 1024
3328 x 3328 (bit depth 14 & 27 MB file size)
22
what is preprocessing?
automatic cleaning up of the raw image before the initial image is visible to us (cleaned up by computer)
23
pre-processing makes ____
post-processing makes ____
corrections
refinements
24
what can happen to individual detector elements? (DELs)
can malfunctions and return no data
25
what is flat field uniformity?
type of preprocessing that corrects for flaws in the electronics/optics of the image receptor system
25
what is the noise reduction for del dropouts?
compensating for malfunctioning DEL's by taking the surrounding 8 DELs and assigning a value to the malfunctioning one
26
what is segmentation?
this occurs to what only?
error that occurs when the computer sees multiple images as a single image
CR (computed radiography) only
27
what is exposure field recognition?
error that occurs when the computer analyzes raw radiation outside the anatomy of interest
27
what is the histogram?
a bar graph created by counting the number of pixels (DELs) at each brightness level
28
how does a histogram visually appeal?
dark pixels to the right
white pixels to the left
29
what are the Smax & Smin?
Smax are the maximum pixel values that are used for analysis
Smin are the minium pixel values that are used for analysis
30
what are the different type of histogram analysis?
Type 1:
Type 2:
Type 3:
detects smax and removes the values to the right (that represent raw radiation) (gets rid of ultra black feeback)
assumes no raw radiation to the right of smax and identifies highest value as smax (abdomen) (assigns a smax)
detects Smin and removes values to the left that represent metal or prothesis (gets rid of ultra white)
31
what are the VOI?
value of interest
different value ranges within the histogram selected to highlight specific anatomy such as bone or soft tissue
31
what are the histogram process errors?
segmentation error
exposure field recognition error
unexpected objects in the data set (led apron, large prothesis, lead gloves, etc)
too little/ too much radiation
mispositioning
32
what is the primary thing that rescaling does?
affects brightness
32
what is rescaling?
the initial processing to make images appear "normal"
33
what is the goal of a lookup tables?
adjust input so that the image appears "normal"
34
what is spatial domain?
processing based on the location of a pixel in the overall matrix
35
what is intensity domain?
processing based on the greyscale value of an individual pixel
35
what does gradation processing primarily control?
contrast
36
what is the frequency domain?
processing based on the size of an object
37
what is data clipping?
a limited bit depth that can limit our ability to adjust the brightness or contrast as it will "clip" the ends of the processing curve
(we don't want to data clip for our radiologist)
38
large objects have ____ ____ & ______ ______
small objects have _____ _____ & ____ _____
large waves & low frequency (large objects are not muted)
short waves & high frequency (small objects are not muted)
38
high pass filtering mutes:
low pass filtering mutes:
large objects
small objects
38
what is the rule?
low pass =
high pass=
low pass= low frequency= large objects
high pass= high frequency= small objects
39
what is detail processing?
breaks down an image into a larger & smaller object based on how many pixels are used to create it
40
what is edge enhancement?
mutes large objects and enhances smaller objects (including artifacts)
41
what is a kernel?
small matrix used to apply effects to a small section of an image or overall image
42
what is speed class?
how sensitive an imaging system is to radiation
43
increasing the speed (class) reduces:
increasing the speed (class) can increase:
patient dose
quantum mottle
44
what do digital images lack?
why is this bad?
visual cues that can indicate correct tecnhical factors
44
the exposure indicator is not ___
an actual exposure reading taken at the image receptor
(median point between Smin and Smax on the image histogram)
45
what speed can modern CR & DR systems operate at?
without?
speed class of 400
the appearance of substantial quantum mottle
46
the standardized EI is based on _____ ______ to the image receptor and is measured in?
actual exposure
Micro-gray (siemens only)
47
what is the target EI? (EIT)
the ideal exposure to the image receptor for a particular projection
47
what is the deviation index?
indicator of how far away a technique was from ideal
48
what is signal-to-noise- ratio? (SNR)
always greater than?
to produce the highest quality image, the signal should be as high as possible, and noise should be as low as possible
1
49
If the index for deviation index were to change by +1 how much increased exposure is that?
and for -1?
25% increase in exposure for +1
20% decrease in exposure for -1
49
what happens if an x-ray results in -3.0?
automatic repeat as quantum mottle is likely
50
what is saturation?
what can be a result of this?
extreme overexposure (10x)
can overwhelm the digital detection system, causing a loss of data
51
what is alternative processing?
how can this affect a radiologist?
processing under incorrect anatomy
(processing a knee as a hand)
affect there ability to window or adjust the image data
52
what is dark masking?
darkens the collimated areas
53
what is the minimal spatial resolution when reviewing an image on a workstation?
6 LP/mm
54
what is the only controlling factor common to film and digital imaging?
distortion
(garbage in, garbage out)
55
Digital images lack the ___ ____ of film-based imaging
visual cues
55
what do digital images lack compared to film-based imaging?
visual cues
56
what can digital imaging compensate for?
what can it not compensate for?
scatter (fairly well)
quantum mottle
(does well with excessive information, but not lack of info)
57
what is the goal of radiologic technique?
ensure that adequate signal reaches the detector
57
_____ ______ will always appear for all imaging system with not enough photons have reached the imaging receptor
quantum mottle
58
what are the benefits of CR? (4)
adaptability
not sensitive to light
different size imaging plates
different speed class
59
what is the exposure latitude of film based?
digital?
-30% to +50%
-50% to +400% (leads to dose creeping) excessive dose for no reason)
60
what is exposure latitude?
margin of error in setting techniques
(range of techniques
61
it takes ____ _____ the normal exposure to saturate a digital image
8-10 times
62
what are the limitations of CR? (3)
processing time
sensitive to background radiation
prone to artifacts
62
what are the two special considerations for CR?
CR plates lose 25% of the image after 8 hours
CR plates are sensitive background radiation and should be erased every 24 hours
63
what are the benefits of DR?
operates at a consistent speed class
high compatibility with PACS (MIMPS)
increased department efficiency
64
what are the limitations of DR?
only can image a single image at a time
bulky, difficult to manage image receptor
65
what is detector element (DEL)?
what is its function?
core of the DR system
DELs capture radiation energy and transfer it into digital information
65
what are the three part of a DEL?
what are there functions?
detector surface (largest part of DEL, absorbs/captures radiation energy)
capacitor (stores the electrical energy from detector surface)
thin-film-transistor (TFT) gateway that releases the electrical charge once the image data is read)
66
indirect conversion systems use ____ ____ to:
indirect has higher?
amorphous silicon
capture the energy of light from phosphor screen made of cesium iodine
efficiency & therefore lower dose
67
what happens when the detector surface decreases in size?
spatial resolution increases
capacitor & TFT cannot decrease in size
the efficiency of the detector (fill factor) decreases & technique must increase
67
Direct conversion systems use _____ _______ to:
Direct has?
amorphous selenium
convert x-rays into an electrical charge
has higher spatial resolution
68
what are photostimulable phosphors?
the core of the CR system
69
barium-fluorobromide & barium-flurochloride crystals ____ with _____
doped
europium
70
After ___ hours an unprocessed PSP will lose ___ of the latent image
8 hours
25%
71
what is a slow scan?
CR plate is removed from the cassette and pulled into the processor (lenthwise)
72
what is a fast scan?
laser beam rapidly moves across the CR plate in rows (crosswise)
73
what does the photomultiplier tube amplify?
light signal from the light channel guide and coverts the signal into a digital signal (electrons)
73
what is the stimulated phosphorescence?
gives of light energy when struck by x-rays & or stimulated by a laser beam (stores & releases)
74
CR is exposed to ___ ____ to:
white light
erase all remaining image data and the plate is returned to the cassette
75
Light emitted by the PSP is channeled by the _____ _____ to the ______ ______
light channel guide
photomultiplier tube
76
Luminescence refers to:
any emission of light in general
76
phosphorescence is the:
delayed emission of light sometime after the original stimulus (exposure) has occurred
(glow in the dark)
76
fluorescence refers to the:
immediate emission of light under stimulation
77
stimulated phosphorescence requires:
re-stimulation
78
what is detective quantum efficiency (DQE)?
detector efficency that can covert input exposure into an output (image)
79
what is pitch?
the distance from the center of one DEL/pixel to center of the adjacent DEL/pixel
80
liquid crystal display (LCD) monitor benefits:
lightweight
portable
inexpensive
generate less heat
long life
less reflective
perfect geometry
81
Display systems are the weakest link:
in the imaging chain
82
The pixel is in the _____ _____ allowing:
on state
Light to pass through, if no electrical current is applied to the pixels
82
what is polarization?
polarizing lenses that use a grid of long slender aligned chains of iodine molecules
83
brightness decreases when temperatures are below:
or higher than:
60 degrees
80 degrees
83
what are LCD monitor limitations?
viewing angle (steradian)
no true black
warm up time (long 20-30 minutes)
84
how much better spatial resolution does monochrome display monitors have compared to color monitors?
monochrome has three times the spatial resolution of color
85
Spatial resolution of a active display matrix is often stated in terms:
of the total number of pixels on the entire screen such as 3 megapixels
86
what is ambient lighting?
lighting in the radiologist reading room should be 2-25 lux, approximately 1/4 of natural background light
87
what is MIMPS?
medical image management and processing system
88
what is processing?
a control computer (server) that directs medical images where they need to go
89
what is CIS?
what is it responsible for?
clinical informational system (site wide)
patient scheduling, billing, & assigns patient number
90
what is RIS?
what is the main purpose?
radiology information system
assigns accession number (unique to patient, time, and exam)
91
what is acquisition?
actual imaging equipment (CR, DR, CT, MR)
or scanning device (analog to digital converter- ADC)
91
what is a HIS?
hospital information system
91
what is AIS?
administrative information system (individual department)
92
what is the display?
images sent via a network to a viewing station such as the radiologists reading room/home, office, or even patient portal
93
what is EMR?
electronic medical record
(pt chart for a single institution)
94
what is storage?
long-term storage in an optical jukebox, raid, or individual disk
95
what is a DICOM header?
extensive & detailed information stored behind the scenes for every image
95
what is lossless compression?
what is lossy compression?
medical images (8:1)
nonmedical images (10:1)
96
what is the DICOM?
who developed it?
digital imaging and communication in medicine (standard)
developed by ACR/NEMA
97
what are the common DICOM commands?
DICOM get worklist
DICOM query
DICOM send
DICOM print
prefetch- pulling prior studies for comparison (radiologists workstation)
97
what is communication language?
common computer language so all components of a PAC system can communicate, regardless of vendor
98
what is meta-data?
image data that cannot be easily seen by the end user
99
what is HL7?
common language for medical data
100
what is true header?
data that is displayed on the image and can be seen by the end user
101
what are mobile generators?
constant potential generator with little to no voltage ripple
102
In mobile radiography the CR is _______ to the IR?
perpendicular
102
In mobile radiography for air/fluid levels:
horizontal beam, patient is as upright as possible
103
what is Cieszynski's law?
1/2 angle between part & IR
103
what are low grid ratios?
5:1- 6:1
104
what is minification gain?
image is minified from the input phosphor to the output phosphor
individual pixels are closer (together) & appear brighter
104
overall brightness of the fluoroscopic image is increased by two processes:
minification gain
flux gain
105
what is the minimum distance from tube to tabletop?
30cm (12 inches)
105
what are the components of the image intensifier?
large glass tube
input phosphor: convert x-ray radiation to light
photocathode: converts light into electrons (1:200 ratio)
electrostatic focusing lens: focus electron stream towards the anode and output screen
anode: attract electrons from photocathode and accelerates them towards the output screen
output phosphor: small (2.5cm) convert electron into light, image is seen upside down
106
what does magnification mode accomplish?
smaller region of patient anatomy imaged
the image is magnified
spatial resolution to that anatomical part is increased (pixels per inch is increased)
image is dimmer due to fewer photons reaching the output phosphor
mA is automatically increased to compensate
patient dose is increased
107
what is flux gain?
conversion of light photons to electrons in the photocathode results in more light photons in the output phosphor
108
what is automatic gain control?
increasing the electrical signal from output phosphor to the display monitor
109
what is magnification mode?
adjusting the FOV (field of view) by moving the focal point
110
what is automatic stabilization of brightness?
maintaining the brightness of image to compensate for part thickness, contrast, and patient position
111
increases collimation reduces:
scatter production and increases contrast
112
pincushion distortion:
pronounced curve near the edges
113
what is the image intensifier subject to?
how can we compensate?
what is normal mA?
quantum noise
increase mA to compensate
around 5 mA
113
what is automatic brightness stabilization (ABS)?
adjustment of the radiologic technique
113
distortion is due:
to curved input phosphor
114
what do dynamic flat-panel detectors operate under?
a pulsed mode called "pulse-progressive mode)
115
vignetting is brighter:
in the center
115
what is charge-coupled device?
a small, flat plate about 1 inch n size
higher image quality than CMOS
115
what is the complimentary metal-oxide semiconductor (CMOS):
what is the main pro?
a small, flat plate about 1 inch in size
cheaper than CCD (coupled charged device)
116
what are dynamic flat-panel detectors similar to?
similar detectors to DR (indirect amorphous silicon; direct amorphous selenium)
116
What are the matrix sizes for dynamic flat-panel detectors?
large matrix sizes (2048 x 2048)
117
What is the exposure rate for fluoroscopy radiation protection?
should not be more than 50 mGy/minute
shall not be more than 100 mGy/minute
117
what are the qualities of a dynamic flat-panel detector?
much higher mA
higher SNR than image intensifiers
less distortion
higher contrast
118
what is the normal fps in fluro?
30 fps
118
In fluoroscopy tube to tabletop not less than?
30 cm (12 inches) for mobile c-arm
38 cm (15 inches) fixed
118
fluoroscopy has a ______ ____ timer that?
5-minute
alerts operator
