Digital imaging test 2 (Bennett)

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Does CR, DR, or both use computers to analyze and manipulate the image?: Both
What uses an image detector system that is cassette-less and hard-wired to a computer network?: DR
What term refers to general x-ray procedures as distinct from other digital modalities such as CT, MRI, and US?: radiographic
What takes place of film in CR?: Imaging plate
How does cassette in CR differ from F/S cassette?: CR cassette is simply a light-proof container that protects an imaging plate from light and handling
What is capable of storing an image formed by incident x-ray photon excitation of phosphors?: imaging plate
After reader releases light stored in imaging plate, the light is converted into a(n) ________, which is then __________: electrical signal; digitized
What is easy about changing from a F/S to CR system?: No room reconfiguration required
What is added to the workflow when you convert from a F/S to a CR system?: Work station and image reader (replace daylight processor)
In F/S, what allowed you to process films without a darkroom?: daylight processor
Does work station in CR increase or decrease throughput?: Decrease (because of time spent in front of computer)
Every CR system has an...: ADC (analog-to-digital converter)
At first, CR cassettes matched sizes of F/S cassettes. Now, CR is limited mainly to what sizes?: 10x12 and 14x17
F/S cassette is designed to ___________ and to ___________: keep light out (to prevent imaging fogging); maintain film-screen contact
What type of cassette had lead backing?: F/S cassette
What measures F/S contact?: Wire-mesh grid
What material is CR cassette made of?: plastic
Why is CR cassette light-tight?: To keep accuracy of gathered data (not as concerned about light fogging image). Close association of high, intense light will erase image in CR
CR cassette protects...: imaging plate
Does CR cassette contain intensifying screens?: No
What does CR cassette have inside to protect against static electricity buildup, dust collection, and mechanical damage to plate?: Antistatic material (usually felt)
What type of backing does the CR cassette have, and what is its purpose?: Aluminum; to absorb x-rays
Imaging plate acquires and holds...: latent image data
An imaging plate is used in...: CR
What is imaging plate made of?: plastic
What layers may imaging plate include?: Protective, phosphor, reflective, conductive, color, support, and backing layers
The layers of the imaging plate may vary depending on the...: manufacturer
What is the outermost layer of the imaging plate?: Protective layer
What is protective layer of imaging plate made of?: Thin, tough, clear plastic
What protects phosphor layer of imaging plate?: Protective layer
What is active/functional layer of PSP?: Phosphor layer
What is active/functional layer of imaging plate?: Phosphor layer
PSP: photostimulable phosphor
What is phosphor layer of imaging plate made of?: Barium fluorohalide phosphors
What layer of the imaging plate may contain a dye to differentially absorb the stimulating laser light to prevent as much spread as possible?: Phosphor layer
Which layer of the imaging plate reduces light spread?: Reflective layer
Which layer of the imaging plate sends light in a forward direction when released in the cassette reader?: Reflective layer
In CR: Since light represents _______, light spread would be _____________: data; data degradation
Reflective layer may be _____ to reduce spread of stimulating light and escape of emitted light: black
Not all imaging plates have a ________ layer or a ______ layer: reflective; color
Reflective layer can cause loss of...: detail
What layer of the imaging plate absorbs and reduces static?: Conductive layer
What layer of the imaging plate consists of added dye between active layer and support layer?: Color layer
What is the purpose of the color layer of the imaging plate?: Light control (dye absorbs stimulating light but reflects emitted light)
What does the support layer of the imaging plate consist of, and what is its purpose?: Semi-rigid material; added strength
What does the backing layer of the imaging plate consist of, and what is its purpose?: Soft polymer; to protect back of cassette
Barcode label/sticker on cassette or imaging plate allows technologist to match image info with...: patient-identifying barcode on examination request
Why should imaging plates be read as quickly as possible?: To avoid losing image info, since energy stored in the IP dissipates over time
Device that extracts the latent image info from the imaging plate: reader
Does CR require a chemical processor?: No
Does CR require a darkroom?: No
After exposure, CR cassette is fed into a _____ that removes the _________ and scans it with a _______ to released the stored ____: reader; imaging plate; laser; e-
Does the reader use chemicals?: No
LASER: light amplification of stimulated emission of radiation
Laser creates and amplifies a...: narrow, intense beam of coherent light
Laser light is coherent because...: all the photons are traveling in the same direction at the same frequency
Laser beam passes through __________ to a(n) ____________ that directs laser beam to surface of imaging plate: beam-shaping optics; optical mirror
Laser scans across imaging plate multiple times in a process known as...: translation
Reader contains a ______ mechanism: drive
Translation can be divided into...: slow scan direction or fast scan direction
Laser beam direction: Fast scan
Direction of plate travel or of laser head: Slow scan
What refers to movement of laser across imaging plate?: Fast scan direction
What refers to movement of imaging plate through CR reader?: Slow scan direction
Scan process produces lines of light intensity information that are detected by a _______ that amplifies light and sends it to a _________: photomultiplier; signal digitizer
Translation speed of plate must be coordinated with...: scan direction of laser
What in the reader collects light?: Fiber optic collecting system (may or may not include photomultipliers)
All readers have ADC after the...: light-gathering mechanism (ex. photomultiplier)
What term refers to a device or system that represents changing values as continuously variable physical quantities?: analog
What digitizes the electronic signal in a CR system?: ADC
ADC assigns each pixel a __________ that corresponds to a level of brightness (and to its position): numerical value
The entire image in CR is divided into a matrix of _____ based on...: pixels; brightness of each pixel
# of pixels in a matrix increases for the same field of view->Pixels must be ______ to fit into that area: smaller
Smaller pixels->______ spatial resolution: greater
Image in CR is digitized by both position (__________) and intensity (_________): spatial location; gray level
What does gray level depend on?: How many photons struck the imaging plate in that particular location
Number of bits per pixel: bit depth
Larger bit depth->____ shades of gray possible->_____ detail the image can display: more; more
The available gray scale for image acquisition and display: bit depth
Bit depth is equal to 2^n where n is the...: number of bits
What does the erasure lamp in the reader do?: Bright light releases remnant/latent info (erases plate) before plate is reinserted into cassette
Does reader return all of e- to a lower energy state?: No, just most of the e-
Since imaging plates are very sensitive to background and scatter radiation, they should be...: erased to prevent a buildup of background signal
When do you need to run imaging plate on an erase cycle to remove background radiation and scatter?: Every 48 hours OR when in doubt about the presence of exposure to the plate OR if last time of erasure is unknown
CR readers have an _______ mode that allows surface of imaging plate to be scanned without recording the generated signal: erasure
Reader may contain ___________ (ex. laser filters) that vary from vendor to vendor: ancillary components
What is typical reader throughput?: 50 cassettes/hour
Ability of the system to image small high-contrast objects: spatial resolution
What determines spatial resolution in CR (according to book, not Bennett)?: Phosphor layer thickness and pixel size (number of pixels)
Thinner phosphor layer in CR->_____ spatial resolution: higher
What is spatial resolution measured in?: lp/mm
What is the spatial resolution of F/S?: 10 lp/mm
What is the spatial resolution of CR?: 2.55-5 lp/mm (2.55 is average; 5 is best)
What predicts maximum spatial resolution of a CR system?: Nyquist frequency
What is one advantage of CR?: Contrast resolution
Can you obtain more recorded detail with F/S or CR?: F/S
___________ (number of recorded densities) is much higher/wider for CR, so loss in ______ resolution is made up for by increase in ______ resolution: Dynamic range; spatial; contrast
Most CR systems sample at __ lines per mm: 10
To image a line pair, you must sample both ____ and ______: line; space
If you sample at 10 lines per mm, the maximum number of lp/mm you can image is __ lp/mm: 5
In F/S, speed of system is determined by...: crystal type, size, and layer thickness
In F/S, you must choose a technique appropriate to _________. In CR, speed class can vary depending on __________: speed of system; what you select
________ represents the level of exposure to the plate required to deliver an acceptable image: Speed class (speed class of operation)
What indicates the speed class of operation?: Level of exposure received by imaging plate
Since speed class is determined by exposure to plate, you should select the _______ possible level of exposure factors to produce a quality image: lowest
After IP has been read, signal is sent to computer where it is _________->Data goes to a monitor where tech can _____ image, _________ it, and send it to _________ for analysis; and then send it to ________ for long-term storage: preprocessed; review; manipulate (post-process); quality control (QC) station (which may also be tech workstation); PACS
Post-processing of an image is not possible after...: it is sent to PACS
Prior to positioning patient and exposing IP, you must select _____ or _______ from the menu choices on your workstation: exam; body part
Selecting proper body part and position on CR workstation is important for the proper _______ to occur: conversion
Improper menu selections (in CR) may lead to...: overexposure of patient and/or repeats
5 areas to consider in CR imaging: -technical factors
-equipment selection
-exposure indicators
-image data recognition
-artifacts
What is the largest area of confusion and largest area of poor ALARA?: Technical factors
Anatomical programmer can adjust __________ depending on area you select and depending on system/vendor: contrast resolution
kVp range in CR: 45-120 (60-110 is optimal because of the k-edge of the PSP)
kVp must be chosen for ________ and type and amount of _______ desired: penetration; contrast
In CR, mAs must be enough to provide proper...: phosphor stimulation
No amount of ____ will compensate for insufficient mAs; however, CR will allow it to compensate slightly for low mAs: kVp
For F/S: Toe of response curve means exposure is too _______. Shoulder of response curve means exposure is too _______.: light; dark
CR plates have a _____ exposure response curve (no toe or shoulder): linear
Quantum mottle is a result of...: insufficient mAs
2 factors to consider when selecting CR imaging cassette: type and size
For systems that vary pixel size according to cassette size, use the ______ imaging plate possible for each exam to get the highest spatial resolution: smallest
2 types of imaging plates: high-resolution and standard resolution
High-resolution imaging plates are most often used for...: extremities, mammography, and other exams requiring increased spatial resolution
When sampling lines (scanning laser) and grid lines are parallel, what occurs?: Moire aliasing artifact
When does Moire aliasing artifact occur?: When grid lines and sampling lines are parallel
Is use of a grid more critical in F/S or CR?: CR (since CR IPs are very sensitive to scatter)
Grid selection factors are _____, ____, and ______: frequency; ratio; focus
Number of grid lines per cm or inch: Grid frequency
Higher grid frequency->_____ grid lines: Finer
Height of lead strips vs. space between lead strips: Grid ratio
Higher grid ratio->_____ scatter absorbed: More
Higher grid ratio->Positioning is _____ critical: more
Use a _____ grid ratio for portables; use a _____ grid ratio for Buckys: smaller; higher
What is the biggest grid problem?: Focus grids
What is the preferred SID now?: 48"
_________ consist of lead strips angled to coincide with beam divergence and must be used within specific distances using a precisely centered beam: Focused grids
Most focused grids tap out under __": 48
Parallel grids do well at __": 48
Are parallel grids or focused grids less critical to beam centering?: Parallel grids
Reduction of the area of the beam that reaches the patient through the use of 2 pairs of lead shutters encased in a housing attached to the x-ray tube: collimation
Compton interactions (scatter) is more likely when _____ volume of tissue is irradiated and _____ kVp is used: large; high
High kVp->Greater chance of ______ interactions: Compton
Collimation results in better ________ due to reduced scatter fog: image contrast
Does collimation affect patient dose?: Yes; reduces patient dose
Adding a black background behind the image (in post-processing) around the original collimation edges to aid in viewing the image: shuttering
______ is aka black border: Shuttering
Shuttering helps in...: viewing the image
Always use lead markers at time of ______: exposure
Measurement of the amount of light given off by the imaging plate: exposure indicators
Amount of light given off by imaging plate is a result of the ___________ the plate has received: radiation exposure
Light from IP is converted into a signal that is used to calculate...: exposure indicator number
Is exposure indicator number a measure of patient dose?: No. It just indicates how much radiation was absorbed by the plate, which gives only an idea of what the patient received
__, __, and ___ are terms used by manufacturers to indicate amount of exposure: S, EI, IgM
Exposure range numbers represent the _______ to ________ diagnostic exposures: minimum; maximum
S value: sensitivity value
S values are all around 2 since...: CR is a 200 speed system
EI: exposure index
IgM: logarithm of median exposure
Higher S number->______ exposure: Lower
Higher EI number->_______ exposure: Higher
Higher IgM->_______ exposure: Higher
Image data recognition (exposure field recognition) is unique to...: CR
___________ establishes the data to be included in the image: Image data recognition
Process of image data recognition may be called...: "ROI finder," "segmentation," or "exposure data recognition"
Image recognition takes place through _________ that determine collimation borders and edges and histogram formation: computer algorithms
____________ determines edges, borders, and histogram relevant values: Image data recognition (exposure field recognition)
Graphical representation of the numerical data on the image plate: histogram
Graphic representation of the numerical tone values of an x-ray exposure: histogram
Histogram values are used to demonstrate the appropriate _______: shades of gray
4 image data recognition modes used by Fuji: -Automatic data recognition
-Semiautomatic mode
-Multiple manual selection mode
-Fixed mode
Image data recognition mode in which image recording range is automatically determined: Automatic data recognition
Image data recognition mode in which collimation is automatically recognized: Automatic data recognition
In automatic data recognition mode, data recognition occurs...: as plate is scanned
Image data recognition mode in which standard histogram analysis is performed: Automatic data recognition
Image data recognition mode in which latitude value of the histogram is fixed, and only a small reading area is used; there is no collimation detection: Semiautomatic mode
Image data recognition mode that is used for smaller field sizes (ex. odontoid, L5/S1 spot, sinuses): Semiautomatic mode
Part must be carefully ________ for semiautomatic mode of image data recognition: centered
Image data recognition mode in which the area of interest is selected by the technologist (and the image is derived from the selected areas imaged in semiautomatic mode): Multiple manual selection mode (Semi-X mode)
Image data recognition mode in which user selects from 9 different areas on imaging plate: Multiple manual selection mode
Image data recognition mode which is useful in cross-table exams for which the body part may not align with automatically selected imaging plate region: Multiple manual selection mode
Image data recognition mode in which user selects exposure index, or sensitivity number, and the value of the latitude from a menu; there is no histogram analysis and no recognition of imaging plate division: Fixed mode
Image data recognition mode that makes IP act like film: Fixed mode
Image data recognition mode in which brightness of image directly reflects technique used: Fixed mode
Any undesirable densities on the processed image other than those caused by scatter radiation or fog: artifacts
5 common types of artifacts: -Imaging plate artifacts
-Plate reader artifacts
-Image processing artifacts
-Printer artifacts
-Artifacts caused by operator errors
Cracks in plate appear as areas of ________ in image: lucency
Adhesive tape residue can cause...: imaging plate artifacts
Static can cause dust and hair to stick to IP and cause...: imaging plate artifacts
Backscatter imaging caused by worn or cracked lead backing can cause...: imaging plate artifacts
Dirt on the light guide in the reader can cause...: horizontal white lines which are reader artifacts
Incorrect erasure lamps can cause...: reader artifacts
Moire pattern error is a...: reader artifact
Dirt/debris on mirror of laser in laser printer can cause...: fine white lines on image which are printer artifacts
Insufficient collimation is an ______ error: operator
Insufficient collimation can change the resulting ________ so it is outside the normal ________ for the body part selected: histogram; exposure indicator range
A backward cassette is an operator error that causes...: a white grid pattern on image
Underexposure is an ______ error that causes ______: operator; mottle
Overexposure _______ contrast: reduces
Digital imaging began with ____ and ____: CT; MRI
CR is based on the phenomenon of...: PSL
The most commonly used digital system is...: CR
The differences in F/S and CR are seen in...: the way the latent image is captured
F/S uses _________ as a scintillator: intensifying screen
Substance/object that emits light in response to an external stimulus: scintillator
CR uses the IR to store e- in __________: high-energy traps
In CR, response to x-ray interaction is seen as trapped ___ in a higher-energy _______ state: e-; metastable
PSL: photostimulable luminescence
Property of a material where light is emitted in response to external stimulation: photostimulable luminescence
What are used to store the latent image in CR?: Photostimulable phosphors
What screens are used in CR?: Storage phosphor screens (SPS)
SPS appears _____ because the small PSP particles scatter light excessively; such a scattering is called _______: white; turbid
SP: storage phosphor
PD: photodiode
___ is a 2-stage image acquisition system: CR
1st stage in CR image acquisition: Latent image is captured on PSP plate
2nd stage in CR image acquisition: Image data is extracted in reader
Does each image on the PSP plate have its own file, or does each whole PSP plate have its own file in the computer?: Each PSP plate is a separate file in the computer, no matter how many images are on the plate
Exposure is aka...: acquisition/capture
When x-ray beam exposes PSP, energy transfer results in excitation of ______ into a ________ state. About __% of these return to ground state immediately with prompt emission of ______. Those remaining return to ground state over time, causing latent im: e-; metastable; 50; light
The latent image in CR is formed by...: trapped e-
CR signal loss is objectionable after approx. __ hours: 8
After 8 hours without processing, CR image...: is degraded so much that it is not of diagnostic quality
CR: Expose->________ and _______ (occur simultaneously)->_____ (not a stage of image acquisition)->Expose...: stimulate; read; erase
In CR reader, latent image is made visible by...: releasing metastable e- with a stimulating laser light beam
Does stimulation cycle of PSL signal acquisition transition all metastable e- to ground state?: No; some excited e- remain. Erasure lamps help to remove any residual latent image
If residual latent image remained on PSP plate, ________ could appear on subsequent use of IP: ghosting
What is it called when residual info from a prior image is shown on another image?: Ghosting/ghost images (NOT the same as a double-exposed image!)
What causes ghost images?: Overexposing the plate (makes it harder to erase plate) AND/OR improper/malfunctioning erasure lamps
IP should be used soon after _______ cycle has been completed: erasure
PSP can be ________ by background radiation: fogged
Components of reader include...: light collecting system, optics, mirror, track
Drive mechanism in reader moves IP at a slow steady rate (_____ scan): slow
While IP is transported in slow scan direction, a deflection device like a mirror deflects the laser beam...: back and forth across IP (fast scan mode)
Fast scan and slow scan drive mechanisms are coupled so laser beam is _________ during retrace: blanked
Sampling and quantization process (simplified): Plate scanned with laser, releasing trapped e- ->Light emitted->Light converted to electrical signal->Analog signal converted to digital signal
Optical features in reader include...: laser, beam-shaping optics, light-collecting optics, filters, and photodetector
In CR reader, _______ is the stimulator: laser
Laser in CR reader is a finely focused beam of _______ light: infrared
As laser beam intensity inc->Intensity of emitted signal ____: inc
Diameter of laser beam affects _____ resolution of CR imaging system: spatial
_________ of laser beam affects spatial resolution of CR imaging system: Diameter
As laser beam penetrates, it _______: spreads
PSP thickness inc->Laser beam spread ____: inc
Laser beam spreads as it travels to the...: rotating/oscillating reflector
_________ focuses light beam onto reflector in CR reader to keep beam diameter small and ensure high ___________: Lens system; spatial resolution
Beam-shaping optics keep beam _____, ______, _______, and _______ constant: size; shape; speed; intensity
Collectors in CR reader are...: fiber optics
Emitted light from IP is channeled into fiber optic collection assembly and directed at...: the photodetector, PMT, PD, or CCD
Where is light amplified and converted into an electric signal in CR reader?: Photodetector (usually a PMT or PD)
What prevents scattered laser light from reaching PMT in CR reader?: Filtration
What improves signal-to-noise ratio in CR reader?: Filtration
Optical filters allow only _____ light to reach photodetector while blocking __________ light: emitted; intense stimulated
Proper filtering improves signal-to-noise ratio. Signal is _______ light; noise is _________ light: emitted; stimulating

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