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134 Cards in this Set
- Front
- Back
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What is the threshold refresh rate that reduces the amount of flickering in the fluoro TV monitor?
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1/30 sec
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What piece of x-ray equipment contains a photocathode, input, and output phosphors?
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image intensifer (II)
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What is vignetting?
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falling off of sharpness toward the edges of an II image
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What piece of equipment functions to stop the exposure once the film is correctly exposed?
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phototimer (AEC)
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Mandatory types of radiographic equipment.
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collimation, light, mirror in collimator, protective curtain, bucky slot cover
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Accessory types of radiographic equipment.
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positioning sponges, compression bands, sandbags
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List 5 advantages of 105 mm strip spot filming over cassette spot filming.
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1. less patient dose
2. lower film contrast (more gray tones) 3. practical storage 4. decreased fluoro tube heat load 5. shortened exam times |
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zinc cadmium sulfide; converts electors to bright image (light photons); 1 in diameter; smaller than input; 5th or last section of II tube
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output phosphor
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metal rings inside the II tube; lenses have a positive charge to attract the negative electrons from photocathode; increasing voltages on each lens from cathode to anode; controls path of electron flow to output phosphor; 3rd section of II tube
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electrostatic lens
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cesium iodide; converts x-rays to light; 9 in diameter; larger than output; 1st layer of II tube; exiting x-rays from patient hit the input
*more x-rays exiting patient= more light photons emitted in II (this is a direct proportion!) |
input phosphor
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draws electrons from photocathode; uses 25 kV to attract electrons; image crosses over here; 4th section of II tube
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accelerating anode
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holds all parts of II tube; vacuumed state so electrons will not collide with anything else (gas particles)
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vacuum glass envelope
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converts light to electrons (photoemission); serves as the II's cathode; 2nd layer of II tube
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photocathode
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Brightness gain of an image intensifier is a result of what two things?
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MG x FG
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An x-ray unit's shortest possible exposure time is known as what?
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minimum response time
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What radiographic modality uses cinefluorography the most?
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cardiac catheterization
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List three things that can vary the brightness level of a fluoroscopic image.
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1. mA (specifically the fluoro mA)
2. kV 3. patient thickness |
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What is the advantage of using a large format spot film (105 mm) over a smaller format (70 mm)?
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improved image quality
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What is the most common diameter of the image intensifier's input phosphor?
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9"
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What is the formula for "minification gain"?
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How much kVp does the accelerating anode need to function?
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25 kV (25,000 volts)
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1
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glass envelope
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2
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focal point
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3.
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output phosphor
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4.
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anode
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5.
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electrostatic lenses
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6.
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electrons
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7.
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photocathode
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8.
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input phosphor
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What are several radiation safety features of fluoroscopic equipment that reduces unnecessary radiation to the patient and personnel?
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1. 5 mA maximum
2. 12" min SID 3. distance between focal spot and table top 4. 10 R/min max exposure allowed at tabletop 5. dead-man foot pedal (switch) 6. automatic collimation 7. Bucky-slot cover to protect operator 8. 5 minute audible, cumulative timer 9, protective curtain (tower drape) 10. filtration |
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What type of fluoroscopic image recording involves altering the pattern of magnetic flux on the recording medium?
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videotape
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What is the purpose of fluoroscopy?
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to view dynamic (motion) anatomy, real time viewing
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In a stationary fluoroscopic unit, where is the fluoroscopic x-ray tube located?
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under the table
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What is the normal tube current during fluoroscopy?
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1-5 mA
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What is photoemission?
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The emission of electrons (photoelectrons) from the photocathode
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At what stage of image intensified fluoroscopy is the number of photons the lowest?
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upon entering the input phosphor
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What is the name of the fluoroscopic system designed to maintain a constant image brightness?
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ABC (automatic brightness control)
(controlled mainly by the fluoro mA) |
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ABC is designed to compensate for changes in what?
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patient positioning (when going for flat to oblique to lateral --- when patient thickness changes)
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When using a 25/17/12 image intensifier tube, which number offers the largest field of view?
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25 cm
As number decreases: mag of image increases larger number=larger FOV and less radiation to patient |
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What happens to resolution when using a multifocus image intensifier tube in the magnification mode?
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resolution improves
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What component of the television monitor transfers the video signal into a visible image?
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fluorescent screen
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In digital fluoroscopy, which piece of equipment is the weakest link ( or produces the most noise/snow)?
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TV camera
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Where is the human eye is visual acuity the greatest?
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where the cones are concentrated (at the fovea centralis)
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What is the difference in what type of light stimulates the rods and cones of the eye?
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rods- low light stimulation
cones- bright light stimulation |
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What is the difference between photopic and scotopic vision?
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photopic- higher light vision, cones, perceives color, more acute
scotopic- low light vision, rods, does not perceive color, 10 times less acute |
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What is the purpose of the potential difference across the accelerating anode?
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increases the kinetic energy of the photoelectrons as they travel to the anode (pushes photoelectrons)
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What is flux gain?
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the ratio of x-rays incident on the input phosphor to light photons exiting the output phosphor
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What is brightness gain?
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the ability of the image intesifier to increase the illumination level of the image; it is the product of minification gain and flux gain; brightness gain is typically 5000-30000 times
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What is the kVp for UGI?
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100-110
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What is the kVp range for BE?
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110-120
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What is the kVp range for air contrast BE?
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80-90
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What is the kVp range for myelograms?
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70-80
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What is the kVp range for SB?
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110-120
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What is the kVp for gallbladder studies?
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65-75
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Light produced at the output phosphor of the II has been increased how many times in intensity since leaving the photocathode?
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50-75
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What is the purpose of the II fluoroscopy?
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To view dynamic images with the same light intensity of radiographic viewing (because of the brightness gain of the image)
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What is the difference of contrast perception and visual acuity?
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contrast perception- the ability of the human eye to detect differences in brightness levels
visual acuity- the place in the human eye where objects are most clear; greatest at the fovea centralis |
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How is an II tube typically identified?
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by the diameter of the input phosphor
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what is one of the major drawbacks of conventional fluoroscopy?
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the low-light level of the image
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Which of the following devices revolutionized fluoroscopy in the 1950s?
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image intensifier
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The input phosphor of second-generation image intensifiers is composed of what phosphor?
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cesium iodide
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What is the function of the input phosphor of an image intensifier?
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to convert x-rays to light
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What is the function of the photocathode of an image intensifier?
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to convert light to electrons
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The photocathode is:
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-referred to as the photoemissive layer
- the cathode of the image intensifier |
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What part of the image intensifier draws the electrons away from the photocathode?
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accelerating anode
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The output phosphor of an image intensifier:
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-converts electrons to light
-is smaller in diameter than the input phosphor -is composed of zinc cadmium sulfide |
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Vignetting is:
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a fall-off in brightness at the periphery of the field
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Cine:
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-is the recording of the dynamic image on film
-requires pulsing of the x-ray beam |
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Which of the following are major differences between cine and spot film cameras?
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-film size, frame rate, patient dose
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Which of the following is not a major disadvantage of spot-film cameras?
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decreased film costs
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Which of the following television tubes is most widely used for fluoroscopic imaging?
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vidicon
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When comparing mirror optics to a television system, which of the following is true?
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Mirror optics provides better resolution, and television provides better contrast.
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Which of the following is not a method of recording the television image?
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cine
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Which of the following is a disadvantage of both television systems and spot-film cameras?
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maintenance costs, decreased resolution
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Which of the following imaging techniques places the greatest stress on the x-ray tube?
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cine
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Which of the following methods does NOT record the dynamic nature of fluoroscopy?
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spot-film camera, spot-film device, multiformat camera, magnetic disk recorder
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In a modern fluoroscope, the fluoroscopic x-ray tube:
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can either be under or over the table.
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The fluoroscope was invented by:
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Thomas Edison
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Compared with a radiographic examination, the primary purpose of a fluoroscopic examination is to visualize:
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dynamic images
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Fluoroscopy normally requires a tube current of:
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1-5 mA
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Compared with a radiography, the x-ray technique for fluoroscopy calls for which of the followinng?
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lower mA
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Automatic brightness stabilization (ABS) is designed to compensate for changes in which of the following?
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patient composition- thickness of part
patient positioning- AP, lateral or oblique |
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The Bucky slot cover of a fluoroscope is a:
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protective device
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Which of the following units of measurement is used to express fluoroscopic image brightness?
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cd/m^2
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Which eye structure is most sensitive to colors?
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cones
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What is the function of the iris?
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control the light level
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The cones are:
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used for phototopic vision
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The fovea centralis is:
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part of the retina
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Visual acuity is the ability to do what?
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perceive fine detail
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The rods are principally used for what?
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dim vision
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In general, during fluoroscopy as compared with radiography:
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the mA is lower
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Which of the following describes the fluoroscopic system designed to maintain constant image intensity?
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automatic brightness stabilization (ABS)
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Which of the following structures is responsible for the vision of dim objects?
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rod
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Which ocular structure immediately precedes the vitreous humor along the path of incident light?
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lens
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Which property is associated with rods but not with cones?
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scotopic vision
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Photoelectric emission:
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is the emission of electrons from an illuminated surface
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At what stage of image-intensified fluoroscopy is the number of the image-forming photons lowest?
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entering the input phosphor
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Image-intensifier brightness gain increases with increasing:
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flux gain
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when an image intensifier receives x-rays at the input phosphor, what is emitted at the output phosphor?
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visible light
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Which of the following is the input phosphor of image intensifiers?
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cesium iodide
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Which of the following is the output phosphor of image intensifiers?
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zinc cadmium sulfide
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The photocathode converts:
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visible light into electrons
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Which of the following is the component of the image intensifier responsible for focusing the electron beam?
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electrostatic lens
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The ability of image intensifier responsible to increase image illumination is called:
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brightness gain
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The minification gain of an image intensifier increases with increasing:
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input phosphor size
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Which of the following is a representative brightness gain for an image intensifier?
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20,000
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If an image intensifier is described as a 25/12 tube, the 25/12 refers to which of the following?
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diameter of the input phophor in inches
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When a multifocus image intensifier is operated in the magnification mode:
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the electron focal point is closer to the input phosphor.
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An image that displays vignetting:
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is dim around the periphery
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With a multifocus image intensifier in the magnification mode:
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spatial resolution is improved
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In a 10/7/5 image intensifier:
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The field of view is largest in the 10 mode.
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An image intensifier has a 5 cm output phosphor and a 45 cm input phosphor. The brightness gain is 10,000. The flux gain is approximately:
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120
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Place the following in proper sequence for image-intensified fluoroscope:
1. electric signal to light 2. electrons to light 3. light-to-electric signal 4. light to electrons 5. x-ray to light |
5,4,2,3,1
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Which of the following applies to output phosphor?
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light emitted
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Vertical television resolution is limited principally by which of the following?
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lines per frame
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The electron beam in a television camera tube is produced by which of the following means?
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thermionic emission
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What is the cinefluorography component of image-intensifier fluoroscopy?
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synchronized
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What is the photoemissive component of image-intensified fluoroscopy?
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electrons from light
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Which of the following is photoconductive?
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target
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What is the principal disadvantage to coupling the television camera to the image intensifier by fiber optics?
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photospot camera cannot be used
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Which of the following refers to the image-intensifier input phosphor?
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cesium iodide
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Which is a critical component is optically coupling an image intensifier to a photospot camera?
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objective lens
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What is the most important component in a television monitor?
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cathode ray tube
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In an optical coupling arrangement, which is nearest the television camera?
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camera lens
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What is the component of the television monitor where the video signal is transformed into an image?
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phosphor screen
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What is the electron beam of the television camera tube?
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modulated
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One television frame is equivalent to which of the following?
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two television fields
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Fluoroscopic television operates at a frame rate of:
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30 f/s
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Horizontal television resolution is principally limited by which of the following?
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bandpass
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What is normally the weakest imaging link in television fluoroscopy?
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television monitor
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the common frame rates during cinefluorography are 15, 30, and 60 f/s because:
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of the frequency of the power supply
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When the electron beam of the CRT is blanked, it is:
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in a vertical retrace
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Which of the following is true about cineradiography?
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The x-ray beam is off when the shutter is closed as a patient protective measure.
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What is the television camera tube component of image-intensified fluoroscopy?
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vidicon
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