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Intro Rad Pro week 3

Intro to Rad Protection week 3

QuestionAnswer
Digital imaging techniques are always applied to computed tomography (CT). ultrasound. magnetic resonance imaging. (All of the above.)
The latent image is formed on the____ for digital radiography. radiation detector
Each matrix pixel represents_____ in digital fluorscopy. atomic number and mass density
In digital radiography, the brightness of the image is determined by pixel values
Digital imaging could only be developed after advances were made in microprocessors. semiconductor memory.
Computed radiography developed in the 1970s with the use of ____ as the image receptor. phosphor
Scanned projection radiography was developed as a complement to____. computerized tomography.
What is the most recent development in digital radiography image receptors? direct capture solid-state devices
Digital radiography first began to be used in clinical settings in the_____. 1980s
Spatial resolution is improved with increased____ in digital radiography. matrix size
The number of visible shades of gray in a digital image is determined by___. bit depth
The dynamic range determines the degree of___ in the image contrast resolution
_____ requires the largest matrix size. Computed radiography
The typical matrix size for digital radiography is____. 1024 X 1024
Spatial resolution is determined by the ratio of____to____. field of view, matrix size
Scanned projection radiography differs from conventional radiography in the lack of scattered x-rays.
In scanned beam radiography the spatial resolution is determined by the number of detectors.
The primary limitation of fanned beam radiography is long scanning time.
Computed radiography utilizes____ for latent image formation. photostimulable phosphor
Conventional x-ray tubes and cassettes are used with____ radiography systems. computed
Detectors acquire info by Scanning array detection
The window level controls image density
The window width controls image contrast
Resolution is controlled by ____ size. Pixel
Detectors currently used in CR include all of the following except capacitor plates
Digital radiography replaces Traditional film
Silicon and selenium receptors are also known as Flat panel detectors
Which type of system uses a a two-part process to convert incoming x-ray photons to an electronic digital signal indirect conversion
During the two part conversion system a ___ converts light into an electronic digital signal photodectector
During the two part conversion system a _____ converts x-ray photons to light Scintillator
A photostimulable imaging plate includes a ___ layer Phosphor, conductor, protective
DR cassettes are also know as Filmless cassettes
The most common phosper use for computed radiography imaging plates is barium fluorohalide bromides and iodides with europium activators
The active layer of the CR imaging plate is made of phototimulable fluorohalides
The latent image is created by energy transfer during photoeletric interactions
The latent image will lose about 25% of its energy in 8 hours
The latent image is processed by a(n) image reader device
The CR imaging plate is scanned by a(n) Helium-neon laser beam
When the CR imaging plate is scanned the phosphors of the latent image release energy in the form of Light
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
Fluoro was developed so that radiologist could view ____ images dynamic
What is the milliamperage used during fluoro 5mA
The image intensifier improved fluoro by increasing image____. brightness
With image intensification the light level is raised to ____ vision. photopic
X-rays that exit the patient and enter the image intensifier first interact with the input phosphor
The output phosphor of the image intensifier is composed of___. zinc cadmium sulfide
The input phosphor converts___ to ___. x-rays, light
The ___ in the image intensifier emits electrons when it is stimulated by light photons photocathode
The number of light photons emitted withing the image intensifier is ___ to the amount of x-ray photons exiting the patient. directly proportional
Electrons hit the ____ after exiting the anode. output phosphor
The ___ is the product of the minification gain and the flux gain. brightness gain
The ratio of x-rays incident on the input phosphor to light photons exiting the output phosphor is called ___ gain. flux
The capability of an image intensifier to increase the illumination level of the image is called its. brightness gain
An image intensifier tube is identified by the diameter of its input phosphor
Brightness gain is typically in the range of___. 5,000 - 30,000
Fluoro for an air contrast barium enema is generally done at ___ kV. 80-90
Viewing the fluoro image in magnification mode increases (all of the above) Contrast resolution, spatial resolution and patient dose
Automatic brightness control(ABC) maintains the brightness of the image by varying kV and mA
The fluoro x-ray tube and image receptor are mounted on a C arm
The carriage commonly support the (all of the above) image intensifier, power drive controls, and spot film selector
During fluoro, the SOD cannot be less than ___ inches 15
The photocathode absorbs ___ and emits ____. light photons, electrons
Electrostatic lenses are used to accelerate and focus electrons
The primary ___ occurs from the acceleration and focusing of the electron beam. brightness gain
The input screen is ____ in shape. concave
The shape of the input screen helps to control distortion
The photocathode is composed of ___ metals photoemissive
Photoemissive materials absorb ____ and emit ___. light photons, electrons
The greater the voltage supplied to the electrostatic lenses, the ___ the acceleration and the ___ the focal point to the input screen. greater, closer
the most common solution for quantum mottle is to increase the fluoro tube mA.
An electron that is described as being metastable: Has higher energy than it should have
Doping of a photostimulable phosphor with Europium results in More stimulable light emission
Photostimulable phosphor image receptors are effective because Metastable states are produced
Photostimulable phosphor image receptors Can be fogged by background radiation
To remove the image background radiation or a previous image, one should Expose the image receptor to intense light
The slow-scan portion of the computed radiography reader Is under mechanical control
Spatial resolution in computed radiography is principally determined by laser beam diameter
The source of the stimulating light is: The laser
How does the computed radiography reader maintain the laser beam as a circle Beam-shaping optics
The x-ray capture element of a computed radiography imaging plate is the BaFlBr (w/europrium)
An advantage of computed radiography over film/screen, regardless of the type of exam, is the relatively constant: Image contrast
Which of the following is an advantage of CR over film/screen. Fewer repeats
Digital radiography Requires computer processing
A scanned projection radiograph Is virtually scatter-free
The image receptor in CR is BaFlCl
Which of the following is used as a radiation detector in a DR Selenium (silicon)
The max frame acquisition rate in digital fluoro is about: 30 frames per second
During digital fluoro The x-ray beam is pulsed
How many video monitors are required for digital fluoro Two
Interrogation time: Is the time needed to switch on the x-ray tube
An advantage of digital imaging over conventional imaging is which of the following postprocessing
The mask image is usually the: Image just preceding contrast
A misregistration artifact Occurs when a patient moves
Remasking Can correct for patient motion
CR Computerized Radiography Barium Fluorohalide with Europium (Cassette w/ IR)
Indirect DR (Digital Radiography) Digital Radiography where photons are converted to light then to electrons
Indirect DR (Digital Radiography) CsI or Gadolinium oxysulfide GdOS
Indirect DR (Digital Radiography) Thin film transitor or amorphous silicon convert electrons captured to light
Direct DR Involves no scintillating crystals
Direct DR Uses amporphous Selenium as capture and coupling element
Minification times flux gain equals Brightness gain
Created by: Joker71