Intro to Rad Protection week 3
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
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| Digital imaging techniques are always applied to | computed tomography (CT).
ultrasound.
magnetic resonance imaging.
(All of the above.)
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| The latent image is formed on the____ for digital radiography. | radiation detector
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| Each matrix pixel represents_____ in digital fluorscopy. | atomic number and mass density
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| In digital radiography, the brightness of the image is determined by | pixel values
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| Digital imaging could only be developed after advances were made in | microprocessors.
semiconductor memory.
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| Computed radiography developed in the 1970s with the use of ____ as the image receptor. | phosphor
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| Scanned projection radiography was developed as a complement to____. | computerized tomography.
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| What is the most recent development in digital radiography image receptors? | direct capture solid-state devices
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| Digital radiography first began to be used in clinical settings in the_____. | 1980s
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| Spatial resolution is improved with increased____ in digital radiography. | matrix size
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| The number of visible shades of gray in a digital image is determined by___. | bit depth
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| The dynamic range determines the degree of___ in the image | contrast resolution
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| _____ requires the largest matrix size. | Computed radiography
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| The typical matrix size for digital radiography is____. | 1024 X 1024
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| Spatial resolution is determined by the ratio of____to____. | field of view, matrix size
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| Scanned projection radiography differs from conventional radiography in the lack of | scattered x-rays.
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| In scanned beam radiography the spatial resolution is determined by the | number of detectors.
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| The primary limitation of fanned beam radiography is | long scanning time.
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| Computed radiography utilizes____ for latent image formation. | photostimulable phosphor
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| Conventional x-ray tubes and cassettes are used with____ radiography systems. | computed
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| Detectors acquire info by | Scanning
array detection
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| The window level controls | image density
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| The window width controls | image contrast
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| Resolution is controlled by ____ size. | Pixel
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| Detectors currently used in CR include all of the following except | capacitor plates
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| Digital radiography replaces | Traditional film
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| Silicon and selenium receptors are also known as | Flat panel detectors
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| Which type of system uses a a two-part process to convert incoming x-ray photons to an electronic digital signal | indirect conversion
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| During the two part conversion system a ___ converts light into an electronic digital signal | photodectector
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| During the two part conversion system a _____ converts x-ray photons to light | Scintillator
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| A photostimulable imaging plate includes a ___ layer | Phosphor, conductor, protective
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| DR cassettes are also know as | Filmless cassettes
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| The most common phosper use for computed radiography imaging plates is | barium fluorohalide bromides and iodides with europium activators
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| The active layer of the CR imaging plate is made of | phototimulable fluorohalides
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| The latent image is created by energy transfer during | photoeletric interactions
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| The latent image will lose about 25% of its energy in | 8 hours
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| The latent image is processed by a(n) | image reader device
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| The CR imaging plate is scanned by a(n) | Helium-neon laser beam
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| When the CR imaging plate is scanned the phosphors of the latent image release energy in the form of | Light
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| During CR imaging plate processing, the laser frees trapped electrons allowing them to return to a lower energy state. This process is known as. | photostimulated luminescence
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| Fluoro was developed so that radiologist could view ____ images | dynamic
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| What is the milliamperage used during fluoro | 5mA
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| The image intensifier improved fluoro by increasing image____. | brightness
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| With image intensification the light level is raised to ____ vision. | photopic
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| X-rays that exit the patient and enter the image intensifier first interact with the | input phosphor
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| The output phosphor of the image intensifier is composed of___. | zinc cadmium sulfide
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| The input phosphor converts___ to ___. | x-rays, light
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| The ___ in the image intensifier emits electrons when it is stimulated by light photons | photocathode
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| The number of light photons emitted withing the image intensifier is ___ to the amount of x-ray photons exiting the patient. | directly proportional
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| Electrons hit the ____ after exiting the anode. | output phosphor
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| The ___ is the product of the minification gain and the flux gain. | brightness gain
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| The ratio of x-rays incident on the input phosphor to light photons exiting the output phosphor is called ___ gain. | flux
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| The capability of an image intensifier to increase the illumination level of the image is called its. | brightness gain
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| An image intensifier tube is identified by the diameter of its | input phosphor
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| Brightness gain is typically in the range of___. | 5,000 - 30,000
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| Fluoro for an air contrast barium enema is generally done at ___ kV. | 80-90
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| Viewing the fluoro image in magnification mode increases | (all of the above)
Contrast resolution, spatial resolution and patient dose
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| Automatic brightness control(ABC) maintains the brightness of the image by varying | kV and mA
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| The fluoro x-ray tube and image receptor are mounted on a | C arm
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| The carriage commonly support the | (all of the above)
image intensifier, power drive controls, and spot film selector
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| During fluoro, the SOD cannot be less than ___ inches | 15
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| The photocathode absorbs ___ and emits ____. | light photons, electrons
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| Electrostatic lenses are used to accelerate and focus | electrons
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| The primary ___ occurs from the acceleration and focusing of the electron beam. | brightness gain
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| The input screen is ____ in shape. | concave
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| The shape of the input screen helps to control | distortion
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| The photocathode is composed of ___ metals | photoemissive
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| Photoemissive materials absorb ____ and emit ___. | light photons, electrons
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| The greater the voltage supplied to the electrostatic lenses, the ___ the acceleration and the ___ the focal point to the input screen. | greater, closer
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| the most common solution for quantum mottle is to | increase the fluoro tube mA.
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| An electron that is described as being metastable: | Has higher energy than it should have
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| Doping of a photostimulable phosphor with Europium results in | More stimulable light emission
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| Photostimulable phosphor image receptors are effective because | Metastable states are produced
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| Photostimulable phosphor image receptors | Can be fogged by background radiation
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| To remove the image background radiation or a previous image, one should | Expose the image receptor to intense light
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| The slow-scan portion of the computed radiography reader | Is under mechanical control
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| Spatial resolution in computed radiography is principally determined by | laser beam diameter
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| The source of the stimulating light is: | The laser
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| How does the computed radiography reader maintain the laser beam as a circle | Beam-shaping optics
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| The x-ray capture element of a computed radiography imaging plate is the | BaFlBr (w/europrium)
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| An advantage of computed radiography over film/screen, regardless of the type of exam, is the relatively constant: | Image contrast
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| Which of the following is an advantage of CR over film/screen. | Fewer repeats
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| Digital radiography | Requires computer processing
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| A scanned projection radiograph | Is virtually scatter-free
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| The image receptor in CR is | BaFlCl
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| Which of the following is used as a radiation detector in a DR | Selenium (silicon)
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| The max frame acquisition rate in digital fluoro is about: | 30 frames per second
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| During digital fluoro | The x-ray beam is pulsed
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| How many video monitors are required for digital fluoro | Two
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| Interrogation time: | Is the time needed to switch on the x-ray tube
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| An advantage of digital imaging over conventional imaging is which of the following | postprocessing
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| The mask image is usually the: | Image just preceding contrast
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| A misregistration artifact | Occurs when a patient moves
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| Remasking | Can correct for patient motion
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| CR Computerized Radiography | Barium Fluorohalide with Europium
(Cassette w/ IR)
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| Indirect DR (Digital Radiography) | Digital Radiography where photons are converted to light then to electrons
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| Indirect DR (Digital Radiography) | CsI or Gadolinium oxysulfide GdOS
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| Indirect DR (Digital Radiography) | Thin film transitor or amorphous silicon convert electrons captured to light
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| Direct DR | Involves no scintillating crystals
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| Direct DR | Uses amporphous Selenium as capture and coupling element
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| Minification times flux gain equals | Brightness gain
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