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Donny Rad SCI lll > Test 2 > Flashcards

Test 2 Flashcards

(90 cards)

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1
Q

what do digital images lack compared to film-based imaging?

A

visual cues

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2
Q

Digital images lack the ___ ____ of film-based imaging

A

visual cues

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2
Q

what can digital imaging compensate for?
what can it not compensate for?

A

scatter (fairly well)
quantum mottle
(does well with excessive information, but not lack of info)

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3
Q

what is the goal of radiologic technique?

A

ensure that adequate signal reaches the detector

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4
Q

_____ ______ will always appear for all imaging system with not enough photons have reached the imaging receptor

A

quantum mottle

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5
Q

what is the exposure latitude of film based?
digital?

A

-30% to +50%
-50% to +400% (leads to dose creeping) excessive dose for no reason)

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5
Q

what are the benefits of CR? (4)

A

adaptability
not sensitive to light
different size imaging plates
different speed class

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6
Q

what is exposure latitude?

A

margin of error in setting techniques
(range of techniques)

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7
Q

it takes ____ _____ the normal exposure to saturate a digital image

A

8-10 times

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8
Q

what are the two special considerations for CR?

A

CR plates lose 25% of the image after 8 hours
CR plates are sensitive background radiation and should be erased every 24 hours

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9
Q

what are the limitations of CR? (3)

A

processing time
sensitive to background radiation
prone to artifacts

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10
Q

what are the benefits of DR?

A

operates at a consistent speed class
high compatibility with PACS (MIMPS)
increased department efficiency

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10
Q

what are the limitations of DR?

A

only can image a single image at a time
bulky, difficult to manage image receptor

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11
Q

what is detector element (DEL)?
what is its function?

A

core of the DR system
DELs capture radiation energy and transfer it into digital information

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12
Q

what are the three part of a DEL?
what are there functions?

A

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)

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12
Q

Direct conversion systems use _____ _______ to:
Direct has?

A

amorphous selenium
convert x-rays into an electrical charge
has higher spatial resolution

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13
Q

what happens when the detector surface decreases in size?

A

spatial resolution increases
capacitor & TFT cannot decrease in size
the efficiency of the detector (fill factor) decreases & technique must increase

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14
Q

indirect conversion systems use ____ ____ to:
indirect has higher?

A

amorphous silicon
capture the energy of light from phosphor screen made of cesium iodine
efficiency & therefore lower dose

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15
Q

what is photostimulable phosphors?

A

the core of the CR system

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15
Q

barium-fluorobromide & barium-flurochloride crystals ____ with _____

A

doped
europium

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15
Q

After ___ hours an unprocessed PSP will lose ___ of the latent image

A

8 hours
25%

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15
Q

what is a fast scan?

A

laser beam rapidly moves across the CR plate in rows (crosswise)

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16
Q

what is a slow scan?

A

CR plate is removed from the cassette and pulled into the processor (lenthwise)

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16
Q

what is the stimulated phosphorescence?

A

gives of light energy when struck by x-rays & or stimulated by a laser beam (stores & releases)

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17
what does the photomultiplier tube amplify?
light signal from the light channel guide and coverts the signal into a digital signal (electrons)
17
Light emitted by the PSP is channeled by the _____ _____ to the ______ ______
light channel guide photomultiplier tube
18
CR is exposed to ___ ____ to:
white light erase all remaining image data and the plate is returned to the cassette
19
Luminescence refers to:
any emission of light in general
20
phosphorescence is the:
delayed emission of light sometime after the original stimulus (exposure) has occurred (glow in the dark)
21
fluorescence refers to the:
immediate emission of light under stimulation
22
what is detective quantum efficiency (DQE)?
detector efficency that can covert input exposure into an output (image)
22
stimulated phosphorescence requires:
re-stimulation
23
what is pitch?
the distance from the center of one DEL/pixel to center of the adjacent DEL/pixel
24
liquid crystal display (LCD) monitor benefits:
lightweight portable inexpensive generate less heat long life less reflective perfect geometry
25
Display systems are the weakest link:
in the imaging chain
26
what is polarization?
polarizing lenses that use a grid of long slender aligned chains of iodine molecules
26
The pixel is in the _____ _____ allowing:
on state Light to pass through, if no electrical current is applied to the pixels
26
what are LCD monitor limitations?
viewing angle (steradian) no true black warm up time (long 20-30 minutes)
27
how much better spatial resolution does monochrome display monitors have compared to color monitors?
monochrome has three times the spatial resolution of color
28
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
29
brightness decreases when temperatures are below: or higher than:
60 degrees 80 degrees
30
what is ambient lighting?
lighting in the radiologist reading room should be 2-25 lux, approximately 1/4 of natural background light
30
what is MIMPS?
medical image management and processing system
31
what is processing?
a control computer (server) that directs medical images where they need to go
32
what is CIS? what is it responsible for?
clinical informational system (site wide) patient scheduling, billing, & assigns patient number
32
what is acquisition?
actual imaging equipment (CR, DR, CT, MR) or scanning device (analog to digital converter- ADC)
33
what is RIS? what is the main purpose?
radiology information system assigns accession number (unique to patient, time, and exam)
33
what is a HIS?
hospital information system
34
what is AIS?
administrative information system (individual department)
35
what is EMR?
electronic medical record (pt chart for a single institution)
36
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
37
what is storage?
long-term storage in an optical jukebox, raid, or individual disk
37
what is lossless compression? what is lossy compression?
medical images (8:1) nonmedical images (10:1)
38
what is the DICOM? who developed it?
digital imaging and communication in medicine (standard) developed by ACR/NEMA
38
what is a DICOM header?
extensive & detailed information stored behind the scenes for every image
38
what are the common DICOM commands?
DICOM get worklist DICOM query DICOM send DICOM print prefetch- pulling prior studies for comparison (radiologists workstation)
38
what is communication language?
common computer language so all components of a PAC system can communicate, regardless of vendor
39
what is meta-data?
image data that cannot be easily seen by the end user
39
what is HL7?
common language for medical data
40
what is true header?
data that is displayed on the image and can be seen by the end user
40
what are mobile generators?
constant potential generator with little to no voltage ripple
41
In mobile radiography the CR is _______ to the IR?
perpendicular
41
In mobile radiography for air/fluid levels:
horizontal beam, patient is as upright as possible
41
what are low grid ratios?
5:1- 6:1
42
what is Cieszynski's law?
1/2 angle between part & IR
42
what is minification gain?
image is minified from the input phosphor to the output phosphor individual pixels are closer (together) & appear brighter
43
overall brightness of the fluoroscopic image is increased by two processes:
minification gain flux gain
43
what is the minimum distance from tube to tabletop?
30cm (12 inches)
44
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
45
what is flux gain?
conversion of light photons to electrons in the photocathode results in more light photons in the output phosphor
45
what is magnification mode?
adjusting the FOV (field of view) by moving the focal point
46
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
47
what is automatic stabilization of brightness?
maintaining the brightness of image to compensate for part thickness, contrast, and patient position
47
what is automatic gain control?
increasing the electrical signal from output phosphor to the display monitor
48
pincushion distortion:
pronounced curve near the edges
48
what is automatic brightness stabilization (ABS)?
adjustment of the radiologic technique
48
what is the image intensifier subject to? how can we compensate? what is normal mA?
quantum noise increase mA to compensate around 5 mA
49
distortion is due:
to curved input phosphor
50
increases collimation reduces:
scatter production and increases contrast
50
vignetting is brighter:
in the center
50
what is charge-coupled device?
a small, flat plate about 1 inch n size higher image quality than CMOS
50
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)
51
what are dynamic flat-panel detectors similar to?
similar detectors to DR (indirect amorphous silicon; direct amorphous selenium)
52
What are the matrix sizes for dynamic flat-panel detectors?
large matrix sizes (2048 x 2048)
53
what do dynamic flat-panel detectors operate under?
a pulsed mode called "pulse-progressive mode)
53
what are the qualities of a dynamic flat-panel detector?
much higher mA higher SNR than image intensifiers less distortion higher contrast
54
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
55
fluoroscopy has a ______ ____ timer that?
5-minute alerts operator
56
In fluoroscopy tube to tabletop not less than?
30 cm (12 inches) for mobile c-arm 38 cm (15 inches) fixed
57
what is the normal fps in fluro?
30 fps

Donny Rad SCI lll (3 decks)

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