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Rad 141 Test #2 Review

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hasamuwi's version from 2015-06-24 18:58

Digital Image Acquisition

Question Answer
Five primary layers of a CR imaging plate, back to frontbacking, support/base, reflective layer, phosphor layer, protective layer
CR imaging plate is covered in what photostimulable phosphor (PSP)?barium fluorohalide coated with europium
The CR image receptor plate/IP is coated with _____ to record the imagephotostimulable phosphors
Functions of CR image receptor imaging plate/IPsolid state image receptor plate/IP, coated with PSP, exposed using conventional xray, records latent or invisible image, developed by a computer and can be digitally manipulated and sent to the PACS server
In CR latent image formation, image forming/exit radiation interacts with _____ layer of the IP and some xray energy is released as visible lightphosphor layer
In CR latent image formation, the remaining xray energy in the IP is absorbed and produces _____electrons
Electrons trapped in the phosphor layer of a CR image receptor imaging plate/IP become the _____latent image
Direct capture DR image receptors consist of _____ to record the imageflat panel detectors with TFTs
Functions of DR image receptors/flat panel detectorsflat panel direct capture detector, fixed detector communicates directly with a computer workstation, not in a cassette holder, mounted in a permanent location, replaces a conventional Bucky tray, direct and indirect detectors with thin-film transistors/TFT arrays
Describe how the latent image is formed in the DR imaging system using DR flat panel detectors with TFTslarge array of detectors absorbs image-forming radiation and converts xray energy into electrical signals. pattern of electronic charges creates a a latent image in the TFT arrays. electrical signals/charges are converted from analog to digital data and processed by a computer
In DR image formation, DR direct flat panel detectors convert image-forming radiation directly into _____electrical charges
TFT array stores electric charges as latent image until _____readout
CR imaging plate latent image formationimage forming/exit radiation interacts with phosphor layer of the IP, some xray energy released as visible light, remaining xray energy is absorbed and produces electrons, electrons trapped in the phosphor layer become the latent image, IP scanned with laser beam inside the CR reader to create a visible image
Convert image forming radiation first into visible light and then to electrical charges or signals. TFT arrays store electric charges as the latent image until readoutIndirect detectors
Convert image forming radiation directly into electrical charges or signals. TFT arrays store electric charges as the latent image until readoutDirect detectors
memorize

Image Plate Care

Question Answer
Image identification for _____. Select Pt ID information and exam with xray number. Information displayed on the CRT/LCD is printed onto the digital images after exposure and image processingDR RIS/Worklist
Image identification for _____. May select Pt ID from RIS/HIS work list. May input Pt ID using a bar code reader or manually enter with the keyboardCR Cassette
CR cassette handling and storageclean outside surface monthly with anhydrous ethanol/ethyl alcohol, can be damaged inside the reader unit, rotate cassettes in the storage area to prolong the life of the IP, store in a radiation safe area outside the xray room to reduce scatter and background radiation
Because IPs are sensative to scatter and background radiation _____use plates soon after erase cycle is completed to avoid fogging of IP
Erase plates if not used within _____ to avoid "ghost" in the image, remove accumulated scatter or background radiation24 to 48 hrs
IP must be processed within _____ of exposure to avoid fading of latent image1 hr
Types of Digital image receptor artifactsDust, dirt, debris, and scratches on IP. Pixel malfunction or failure, ghost images (environmental or background radiation, incomplete erasure or previous image), rough handling or faulty construction of IP, damaged or cracked IP
DR detector image lag, is caused by the persistence of an image because _____Electronic charge is still produced after the radiation beam coming from the xray tube has been turned off
memorize

Screen-Film Care

Question Answer
Image identification for _____. Photographic method. Photoflash Pt ID information on lead blocker of cassette.Screen-film images
Screen-film storage conditionsStore on end (like books on a bookcase), away from heat or radiation sources, cool and dry (68 degrees F, and 40-60% humidity), use older film first, do not use past expiration date to prevent fog
FIFO method of screen-film storageFirst-in First-out, rotate stack of boxes and use older film first
Screen film should be stored at _____ degrees Fahrenheit68
Screen film should be stored at _____% humidity40-60
Any unwanted or added density recorded and displayed in the imageImage fog
Sources of image foglight, radiation, age, chemical processing problems, heat and high temperature, darkroom safe-light and filter
Any unwanted mark recorded and displayed in the imageimage artifacts
Types of handling and storage image artifactslight and radiation fog, static electrical discharges, pressure artifacts
Types of static electrical discharge artifactstree/bush, smudge, crown
Intensifying screen layers - Back to frontcardboard support/base, reflective layer/absorbing layer, phosphor layer, protective layer
_____ can be replaced by a(n) _____ in an intensifying screen to improve recorded detail and spatial resolutionreflective layer; absorbing layer
_____ absorb image forming xrays and convert them into visible light which exposes screen-film emulsion and produces the latent imagerare earth phosphors
Rare earth phosphors absorb more xray photons in the _____ diagnostic range and convert the photons to more light40-75 KV
Evaluate screen-film contact by using the _____. Should visualize sharp lines in the displayed image. Areas of blurriness or fuzziness indicate poor screen-film contactwire mesh screen test
Poor screen-film contact (PSC) reduces _____ and _____ displayed in the imagerecorded detail; spatial resolution
memorize

Intensifying Screen Speed

Question Answer
Factors effecting intensifying screen speedsize of phosphor crystals, thickness of the phosphor layer, type of phosphor, spectral matching
Matching the color emission spectrum of the screen with the proper film colorspectral emission
Fast screen speeds have these characteristicslarge crystals, thick phosphor layer, less recorded detail and spatial resolution in the image, more quantum mottle/image noise, reduces patient radiation exposure and dose
Why does a fast screen speed reduce patient dose?less mAs is required, 200 speed screen would require 50% less mAs than 100 speed
Slow screen speeds have these characteristicssmall crystals, thinner phosphor layer, more recorded detail and spatial resolution in the image, reduces quantum mottle/image noise, increases patient radiation exposure and dose
Random (uneven) distribution of xray photons across the surface of an intensifying screen. Reduces recorded detail and spatial resolution in an imagequantum mottle/image noise
Quantum mottle/ image noise is mostly caused by _____fast screen speeds and low mAs levels
To reduce image noise you must increase the number of xray photons by _____ or _____use a slower speed screen or increase the mAs
In screen-film systems, speed determines proper exposure to the image receptor to achieve _____optimal image density
In digital systems, the receptor exposure (mAs and KV) determines the _____ at which the system operatesspeed class
_____ speed class requires less exposure to the CR plate (less mAs)faster
_____ speed class requires more exposure to the CR plate (more mAs)slower
Exposure indicators for a Fuji systems (Sensativity (S) number)Inversely proportional - low exposure = higher S#, high exposure = lower S#. Optimal between 200 and 400
Exposure indicators for Kodak systems (Exposure Index (EI))Directly proportional - low exposure = lower EI value, high exposure = high EI value
Exposure indicators for Agfa (log value (LgM)) systemsDirectly proportional - low exposure = lower lgM value, high exposure = higher LgM value. Optimal between 2.0 and 2.2
memorize

Digital Image Post-Processing

Question Answer
Digital images will have the same _____ regardless of exposure levels (mAs and KV used)display brightness
images with noise and mottlelow mAs values
increases patient dose and may create scatter in the image and reduce image contrasthigh mAs values
computer can display _____ gray shades in a single digital image1000
used to alter image brightness levels/image densities, make image appear brighter or darkerwindow level
used to alter image contrast levelswindow width
_____ contrast with many gray shades in the image - appears graylower
_____ contrast with only a few shades of gray and mostly black and whitehigher
memorize

Image Density Influencing Factors (Matching)

Question Answer
thick anatomical partReduces image density (must increase technique (mAs or KV))
dense tissue (ex. bone)Reduces image density (must increase technique (mAs or KV))
additive pathology (disease)Reduces image density (must increase technique (mAs or KV))
slower speed screens Reduces image density (must increase technique (mAs or KV))
mismatch film-screen color (reduces speed)Reduces image density (must increase technique (mAs or KV))
using collimation or a BLD deviceReduces image density (must increase technique (mAs or KV))
using a radiographic gridReduces image density (must increase technique (mAs or KV))
increase the amount of beam filtrationReduces image density (must increase technique (mAs or KV))
no image fog/scatter and background radiationReduces image density (must increase technique (mAs or KV))
under-developing screen-film in chemical processingReduces image density (must increase technique (mAs or KV))
anode heel effect - less radiation intensity and less image density on anode side of tubeReduces image density (must increase technique (mAs or KV))
thin anatomical partIncreases image density (must decrease technique (mAs or KV))
lighter tissue (ex. air)Increases image density (must decrease technique (mAs or KV))
destructive pathology (disease)Increases image density (must decrease technique (mAs or KV))
faster speed screenIncreases image density (must decrease technique (mAs or KV))
spectrally match film-screenIncreases image density (must decrease technique (mAs or KV))
not using collimation or BLD deviceIncreases image density (must decrease technique (mAs or KV))
not using a radiographic gridIncreases image density (must decrease technique (mAs or KV))
remove primary xray beam filterIncreases image density (must decrease technique (mAs or KV))
image fog/scatter and background radiationIncreases image density (must decrease technique (mAs or KV))
over-developing screen-film in chemical processingIncreases image density (must decrease technique (mAs or KV))
anode heel effect - more radiation intensity and more density on cathode side of tubeIncreases image density (must decrease technique (mAs or KV))
memorize