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154 Cards in this Set
- Front
- Back
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Minimum lead equivalency needed for fluoroscopy unit protective curtain
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0.25mm
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Minimum lead equivalency needed for fluoroscopy unit bucky slot cover
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0.25mm
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Max exposure rate of a unit without automatic exposure controls
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5 R/min
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Total filtration permanently required in the useful fluoroscopic beam should not be less than
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2.5mm A1
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Max cumulative time for continuous exposure is:
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5 min
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Minimum lead equivalent needed for gonadal shielding
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0.5mm
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This unit is directly proportional to the exposure delivered to the patient
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mAs
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Unit for measurement of patient's absorbed dose
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Rad
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Source-skin-distance minimum
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12 inches
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If X-ray source is below the table, useful beam exposure must be measured at what distance above the table top
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30 cm
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Patient exposure rate for 5 min of fluoro time
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10-25 rads
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Fluoro units operate at this tube current
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2-5 mA
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Intensity measured at the table top at 80 kvp should not exceed how much R/min for each mA of tube current
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2.2 R/min
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Table top exposure rates for units without auto exposure control must be measured every
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3 years
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Dark adaptation for the eye takes how long
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30 minutes
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Decreased brightness gain at the image periphery is called
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Vignetting
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Vertical line rate is normally
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525 lines
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Video disc recorders record at a maximum frequency response rate of
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30 frames per second
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Output intensity is measured in which unit
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mR or R
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Target-to-tabletop distance must be greater than and should be greater than...
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12 and 18 inches
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Normal viewing distance
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10-15 inches
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Integration time (for brain to recognize an object)
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0.2 seconds
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Typical X-ray exposure for routine 2minute upper GI series
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6 roentgens
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Scatter radiation exposure at 1 foot from the pt could be as high as
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500 mR per hour
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Most scatter occurs at which direction from the primary beam
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135 degrees
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mA setting for spot filming where a spot film camera is not used
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150 mA
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Max exposure during 9 month pregnancy for occupational worker
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500 millirems
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Time for fluoro table to move from horizontal to vertical position
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20-25 seconds
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Most commonly used video disc frame rate
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30 frame/sec
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Greatest dose to the pt comes from spot filming cameras using this film size
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105 mm
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Recognition/integration time of human eye
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0.2 sec
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Which CCTV system results in least pt exposure
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Plumicon
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Total permanently fixed filtration of the useful beam must be
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3 mm aluminum equivalent
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At tube current at 80 kvp, the max intensity shld be
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2.2 rads per minute
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mA setting for fluoro is typically less than
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Less than 5 mA
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Predetermined time limit for fluoro beam
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5 minutes
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Max exposure rate for all combos of tube potential and current, for those with auto exposure control
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10 roentgens/minute
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Max exposure rate for all combos of tube potential and current, for those without auto exposure control
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5 roentgens/ minute
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Max whole body dose equivalent fo persons over 18
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1250 millirems per calendar quarter
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For exposure to pregnant women, risk of malformations is increased at doses above
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15 rad
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High radiation area could expose whole body in one hour to dose greater than
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100 millirems
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A radiation area could expose a major portion of the body in one hour to dose greater than
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5 millirems
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SI unit analogous to the rad is
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Gray
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Rad is a unit of
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Absorbed dose (unit)
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SI unit analogous to the rem
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Sievert (unit)
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Cardiac cath exam results in a bone marrow dose of approximately
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190 millirads
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5 minute fluoro patient exposure
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10-30 roentgens
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If skin exposure was 5 roentgens, dose to the fetus
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100 millirads
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Barium enema exam causes what dose to gonads
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500 millirads
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Exposure of occupational worker to 5 rems requires state notification within
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24 hours
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Exposure of 2 rems within a quarter requires state notification within
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Within 30 days
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Exposure reduction of .25 mm lead
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97%
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Maximum dose whole body dose exposure per year
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5 rems per year
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Leakage radiation at a distance of 1 meter from the target cannot exceed
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100 milliroentgens in 1 hour
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Patient positioning for gallbladder spot films
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Rpo, upright, inhalation
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Tube current and potential must be recorded how often
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Weekly
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Size of input: output phosphor diameter
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Minification gain
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Scattered radiation received is proportional to
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Dose received by the patient
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Most effective medium for static viewing in terms of reducing patient dose
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Video disc recorder
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Ratio between the vertical and horizontal lines on the TV monitor
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Kell factor
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Contrast of the image intensifying tube is measured by
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conversion factor
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maximum magnification for cinefluorography is done via which method
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total over framing
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A film badge reports in which units
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Rems
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Line pair grid is used to measure
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Resolution - resolving power
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Standard CINE skin exposure in one minute
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1-5 R/min
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Max tech exposure from barium enema at distance of one foot from the table (per hour)
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400-500 mR/hr
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Statistical fluctuations of xray photons cause
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quantum mottle
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This maintains a fixed dose to the input phosphor
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the AEC (automatic exposure control)
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Ratio of photons that leave the output phosphor to the number of Xray photons that strike the input phosphor
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Flux gain
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Increasing KVP beyond optimum range can result in
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Poor subject contrast
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Half value layer determines which characteristic of the Xray
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Xray quality
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Ability to distinguish separate objects in line pairs per mm
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Resolving power
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The portion of the image intensifier responsible for magnification
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electrostatic lenses
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resolution of a 9" image intensifier tube
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3.5 lp/mm
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light photons intercepting when electrons strike a fluorescent screen forms a...
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Real image
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xray interaction with contrast media produces what effect
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photoelectric
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Proper parameters for an overhead fluoroscopy tube?
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4.5R/min with a water phantom 30cm above tabletop
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Magnification with an image intensifier is achieved at which site
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electrostatic lens site
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Fluoro with a grid in place affects exposure rates how
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1.5-2 x higher
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Greatest radiosensitivity of fetus occurs when
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2-8 weeks gestation
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safest time to expose a woman of childbearing age?
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Day 1-10
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Primary protective barrier for a dedicated C-arm is what
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Input phosphor
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Formula for calculating the maximum permissible lifetime dose for a technologist
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age x 1REM
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Maximum dose rate for a patient undergoing routine fluoro
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5 R/min
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The quantity of the beam is controlled by which unit of measurement
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miliamperage
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which filming method gives the best resolution?
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Spot film radiograph
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Which fluoroscopic method gives patient dose reduction of up to to 95%?
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video disc recorder
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100erg/gram is equivalent to?
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1 rad
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Fluoro units with AECs or CINE cameras must have physicist calibration how often
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every year
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Maximum exposure level while using boost position?
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20 R/min
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Which imaging modality has the best resolution
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Radiograph
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Image intensifiers convert xray photons to...?
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xray photons to light to electrons to light
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central portion of the tube possesses the greatest
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Resolution
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Compared to the input phosphor, the image output phosphor is...
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Smaller and brighter
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Input phosphor of 2nd generation tube is made of..
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Cessium iodide
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How does moving the image intensifier away affect the patient dose
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Increases the patient dose
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As spot film size increases, what happens to the patient dose?
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Patient dose increases
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Unit used to specify the quality of an Xray beam
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HVL
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Visual acuity is defined as
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the ability of the human eye to perceive fine detail
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cycles per time unit in a TV camera is known as...
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bandwidth
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types of pick-up tubes
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plumicon, vidicon, orthicon
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TV camera element which converts light to an electric signal
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Pickup
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Output intensity is measured in...
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mR or R
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Brightness ratio of the periphery to the center of the output screen is termed:
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Contrast
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Mag mode input screen diameter change formula for exposure rate increase
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(After/before)squared
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How is resolving power measured?
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Line pairs per milimeter
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Characteristics of contrast
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High atomic number and low toxicity
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Which factors produce a brighter image at the output phosphor?
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Flux gain and minification
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What type of TV system has all its signals carried through cables?
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Closed circuit TV
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Output intensity of a tube is measured in...
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Miliroentgens
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Electronic intensification occurs when...
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Electrons are moved at high speed from photocathode to output phosphor
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genetic dose means..
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Effects exhibited in future offspring of persons who have been irradiated
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Dose effect curve that radiation protection guides are based on...
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linear nonthreshold curve
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how many rads of acute x-radiation to the eyes cause cataracts?
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Hundreds of RADs
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A disadvantage of thermoluminescent dosimeters
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No permanent record is provided
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Rem is a unit of
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Absorbed dose equivalent
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Rad is the unit of:
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Absorbed dose
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Half value layer defined
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The thickness of a specified substance which reduces the exposure rate of the primary beam by one half
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CINE exam typical skin exposure/min
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2-5 roentgens/minute
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A material placed in the useful primary X-ray beam to absorb preferentially the less penetrating radiations
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Filter
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Most common material used in thermoluminescent dosimeters
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lithium fluoride
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Leakage radiation at a distance of 1 meter from the target cannot exceed
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100 milliroentgens in 1 hour
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Instrument used to expose film to precisely controlled steps of increasing light intensity is:
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sensitometer
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Device made up of different density filters
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step-wedge
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Which effect is responsible for producing an image in a barium enema examination?
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photoelectric effect
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Very radiopaque structures fulling up the center of the imagine field in AEC pediatric fluoroscopy causes
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Patient exposure to increase to a maximum
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Primary barrier for the Xray beam is the
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image intensifier
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Beam alignment and image intensifier resolution and contrast should be monitored how often...
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Monthly
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Due to the phosphor aging, which should be measured periodically to check the contrast
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conversion
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This is considered a stochastic effect
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Cancer
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Line pair grid is used to measure
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Resolution
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Primary xray interaction taking place within the contrast media
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photoelectric effect
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Maximum mag during CINE is achieved with which filming method
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total over framing
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Ratio between the vertical and horizontal lines on the TV monitor
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Kell factor
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The primary protective barrier for a dedicated C-arm unit
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Input phosphor of the image intensifier
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For fixed fluoroscopic tube, the distance from the source to the tabletop shall be
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15 inches
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Lead aprons word during fluoroscopic procedures are designed to protect the radiographer from
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compton scattered radiation
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9" image intensifier tube has an inherent resolution of approx
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4 lp/mm
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High resolution area is defined as an area where an individual can receive a dose of
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100 mR/hr
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Light scattering causing less contrast is called?
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Veiling glare
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When X-rays are directed toward the patient, most X-rays are...?
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Absorbed by the patient
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annual whole body dose equivalent for persons under 18 years of age
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0.5 Rem
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Radiation effect in which severity varies with radiation and for which a threshold may occur
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Non-stochastic effect
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Speed of a camera system is calculated by dividing focal length by lens diameter. Number is called?
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F-number
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CINE framing due to poor optical coupling
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Underframing
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How to eliminate quantum noise
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Increase tube current-mAs
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Vertical resolution of the TV system is the ability to resolve
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Horizontal lines
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Purpose of viewing a TV system with interlaced horizontal scanning is...
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Reduce image "flicker"
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Conversion factor is calculated how
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Light intensity at the output phosphor divided by the dose rate
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Recording head of a video disc recorder uses what to record images
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laser light and magnetic fields
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Which component of the image intensifier changes the field of view from 9" to 6"
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electrostatic lens
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How does going from 9" to 6" change patient dose
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Increases patient radiation dose
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Conversion factor is
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Radiation absorption by the input phosphor to output phosphor light gain
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type of contrast that's more likely to cause renal effects
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High Osmolarity
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