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Registry Review Chapter 12 and 13

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  • DICOM deals with ?
    communications
  • What factors affect spatial resolution?
    OID, SID, FSS, Patient factors, motion, angle of tube
  • The range of histogram data set that should be included in the displayed image is determined by the ?
    VOIs
  • What are the two visibility factors in determining image quality?
    Brightness and contrast
  • Casts and what kV do you add?
    Small-medium= 5-7 Large= 8-10 fiberglass= 3-4
  • What determines which values from the histogram analysis will be used in the image?
    The VOIs
  • How does added filtration effect the emission spectrum ? WHY?
    reduced amplitude ( because lower energies are filtered out) and a shift to the right
  • What is the most accurate type of timer?
    electronic
  • What are the two geometric factors in determining image quality?
    spatial resolution and distortion
  • This post processing technique improves the visibility of small, high contrast structures?
    edge enhancement
  • What makes up the histogram?
    the VOIs
  • LUT does what?Why?
    gives the contrast using the VOI's
  • The four properties of a photon?
    frequency, wavelength, amplitude and velocity
  • What are the GCF for various grids?
    no grid- 1 5:1 - 2 6:1- 3 8:1- 4 10:1- 12:1- 5 16:1 - 6
  • Radiographic contrast would be standardized with the ?
    fixed kV-variable mAs technique chart
  • Alternating current is produced with a?
    generator
  • mAs is a quantitative factor and is __________________ _____________________ to the number of photons delivered to the IR AND the patient.
    directly proportional
  • An increase in kVp would ______________ the _________ of the emission spectrum?
    increase , amplidude and position
  • How long is the filament in the tube?
    1-2 cm
  • The HVL is the measurement of beam quality or quantity?
    quality
  • The number of bits per pixel is called?
    bit depth
  • Lossy compression can be used for _________________?
    video recordings
  • The use of optimum kV for small, medium and large body parts is the premise of?What type of charts do we use?
    APR, fixed kV and variable mAs charts
  • What is the formula for calculating high voltage generator power?
    max mA x 100 kVp
  • Gray in air is the measurement for 3 things?
    exposure, quantity, intensity
  • What is it when the software determines greyscale?
    dynamic range
  • Is the efficiency of x-ray production directly, indirectly proportional or not affected by the tube current?
    not affected by
  • If a system has 8 bits how many shades of grey does it have ? Formula?
    2N ( 2 x the number of bits)=2x2x2x2x2x2x2x2=256
  • What does PACS do?
    picture archiving
  • What is the fluoro input phospher made of?
    cesium iodide
  • where is the step down transformer located?
    the filament circuit
  • What two indicators can show that an image taken is acceptable?
    EI or DAP
  • Increasing the kVp increases what?
    the number of photons
  • X-ray photon energy is measured in ?
    kEv
  • How is SID related to exposure rate and receptor exposure?
    As SID increases , exposure rate decreases and receptor exposure decreases
  • the source of radiation in the tube is?
    the focal spot
  • What is the basic photometric unit?
    lumen
  • What analyzes the image we just took?
    Histogram
  • Focal spot blur is reduced by using?
    a small focal spot
  • What are the four aspects of image quality?
    Brightness, Contrast, Spatial resolution and Distortion
  • What are the three items in order from beginning to end that happen in a CR reader ? PMT converts light energy to signal, stored energy released as light, signal is sampled and digitized.
    stored energy released as light, PMT converts light energy to signal, the analog electrical signal is sampled and digitized
  • The difference in the waveform between primary and secondary sides of the high voltage transformer is ?
    amplitude
  • Changes in ______________ result in direct proportional changes in the amplitude of the emission spectrum?
    mA and time
  • Sampling frequency of an imaging system determines the ?
    pixel size
  • What controls contrast? kVp or mAs?
    kVp
  • The emission of light when stimulated by a high-intensity laser beam is?
    photostimulable luminescence
  • The funky thing that comes up on the screen as soon as you take the image is called?
    histogram
  • Window level deals with ? Window width deals with ?
    brightness, contrast
  • Increased quantum noise is seen in a digital image with ?
    severly lower than needed mAs
  • Lossless and lossy. Which is good and bad?
    Lossless-good Lossy bad (less letters in this word and you cant diagnose with less)
  • What does pixel depth refer to?
    shades of grey
  • A diode allows electrons to flow from _____________ to _______________?
    cathode to anode
  • The percentage of x-rays that have reached the detector and have been captured is the ?
    fill factor
  • X-ray intensity is proportional to?
    KVx2
  • What is the filament made of?
    thoriated tungsten
  • What are located on the x and y axis of the histogram?
    X-(the bottom) - specific exposure values Y(the side)- the number of pixels
  • Which exposure variable is controlled by the AEC?
    seconds/milliseconds
  • Foreshortening shape distortion is caused by?
    an angled body part when the beam is perpendicular to the IR
  • What are the prime factors used to create the image?
    kVp, mAs and distance
  • The angle of the target can be between?
    7-20 degrees
  • With a fixed matrix CR, changing to a larger IP for the same FOV will result in?
    larger pixels
  • An increase in mAs would ___________ the ______________ of the emission spectrum?
    increase, amplitude alone
  • How do you calculate absorbed dose?
    joules divided by weight
  • Exit radiation is converted to visible light with the direct or indirect system?
    indirect
  • What does the characteristic curve have to do with ?
    LUT
  • What is OER and what is the number for x-rays?
    Oxygen Enhancement Ratios and the for x-rays it is 3
  • Image forming rays include those that have ________________ and ______________?
    absorbed and transmitted
  • Which automatic exposure device works by converting x-ray photons first into light and then an electronic signal?
    phototimer
  • At energies below 40 keV what is the main ex-ray interaction in soft tissue?
    photoelectric
  • Contrast is a quality related to the _____________ of the radiographic image.
    visibility of structures
  • A CCD used in fluoro provides high________?hint* 3 things
    spatial resolution, signal to noise, DQE
  • What are the four steps of creating an image with CR? Beginning with the metastable state, INCLUDING erase, stimulate and read
    metastable state, stimulate, read and erase
  • Electron interactions at the inner shell of the target produce what type of radiation?
    characteristic
  • How does added filtration affect the emission spectrum?
    Reduced amplitude and a shift to the right
  • What is the activator in a phosphor?
    europium
  • where is focal spot blur the greatest?
    at the cathode
  • Optical density is mainly controlled by changing the?
    mAs
  • Lowering kVp ___________________patient dose and _________________image contrast?
    increases and increases
  • What is another name for recorded detail?
    spatial resolution
  • Differential absorption imaging is primarily caused by ?
    photoelectric
  • When selecting the focal spot size what is really being chosen?
    the actual filament size
  • The histogram turns into the s-curve box on the computer- what is that called?
    LUT
  • HL7 deals with?
    medical terminology text
  • What is the formula for calculating pixel size? !!! 1 inch= 25.4 mm
    FOV/matrix size
  • Why do you have better spatial resolution with a small FSS?
    because you have less divergence
  • What is constant in a parallel circuit?
    volts
  • How would dirt in the light guide of a CR reader appear on a digital image?
    white lines
  • How is HVL lowered ? a decrease in mAs, kVp or distance?
    kVp
  • If it is converted to light is it indirect or direct conversion?
    indirect
  • The recommended SID's that can be used with a focused grid describes what characteristics of the grid?
    focal range
  • Heat unit formulas:
    Single Phase- kVP x mAs x sec, 3 phase 6 - 1.35, 3 phase 12 - 1.41, high frequency - 1.66
  • In DR, NYQUIST is referring to which of the following?
    the sampling frequency of the digital data
  • How can specular reflection be assessed?
    turning off the monitor in ambient light?
  • What are the geometric factors that can be used by the technologist?
    SID, OID, FSS
  • Is emphysema destructive or additive? Why?
    destructive because the alveoli stretch out (more air)
  • Smoothing can be applied to a digital image to mask which of the following? artifacts, metal objects, fog, noise
    noise
  • Is ABC found in flouro or radiography?
    fluoro
  • fluoro unit uses _____________ mA and a ___________ beam.
    high, pulsed
  • Inherent filtration is where?
    part of the tube design
  • Increased quantum noise is seen in a digital image with ?
    severely lower than needed mAs
  • What is the weighting factor of the brain? Bone marrow, colon and stomach?
    brain is .01 the others is .12
  • A moving charged particle creates what?
    a magnetic field perpendicular to the causative motion
  • Does wide window width increase of decrease contrast? Why?
    decreases (more shades of grey)
  • What chemical IS the phosphor in a CR plate?
    barium flourohalide
  • An increase in kVp would __________________ the ________________ and ________________of the emission spectrum?
    increase, amplitude and position
  • Where is the source of electrons?
    filament
  • Once the part has been penetrated a doubling of the mAs will result in how much exposure to the IR?
    double
  • Increasing filtration will have what effect on beam intensity?
    it will decrease it
  • What quality control standard for flat panel displays was released in 1998?
    VESA
  • Difference in the brightness levels or densities is:
    image contrast
  • What is the source of radiation in the tube?
    focal spot
  • What component replaces the video camera in a flouroscopy unit?
    CCD
  • To prevent a Moire pattern on a CR digital image, it is best to have the grid lines running ________________ to the direction of the laser beam?
    perpendicular
  • An increase in mAs would ___________the______________of the emission spectrum.
    increase, amplitude alone
  • Does narrow window width increase or decrease contrast? Why ?
    increases contrast (less shades of grey)
  • A scattered x-ray from a Compton interaction usually retains what type of energy from the incident photon?
    most
  • What is Task Group Report 18 for?
    It is a procedure manual for testing digital display devices?
  • What does the atomic number of an atom mean? HINT* deals with protons. EXAMPLE:
    Atomic number equals the number of protons Aluminum has an atomic # of 13. How many protons does it have? 13
  • What is the function of contrast?
    to make details visible
  • What is another name for a range of exposures?
    dynamic range
  • Which of the following would NOT be considered ambient light? monitor light, lamp light, natural light, florecsent light
    monitor light
  • The range of histogram data set that should be included in the displayed image is determined by the ?
    VOI
  • Text data and email are generated at a __________________ workstation in PACS?
    RIS
  • Spatial resolution is improved with increased ? hint* think equipment
    increased pixel density
  • What is the Magnification formula?
    MF= SID ----- SOD
  • Characteristic x-rays are produced by ?
    released binding energy
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