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90 Cards in this Set

  • Front
  • Back
# of filaments in average machine
fxn of bucky
to remove grid line artifacts
primary beam
aka useful beam
increase TID (tube-image distance)
magnification decreases
detail increases
disc angle with the most heat
smallest angle
determines if exposure is tube safe
tube rating chart
increase in OFD (object film distance)
magnification increases
detail decreases
results in the highest density
mighest mAs to kV ratio
spinning top test set to 1/20= how may dots?
6, (120x1/20=6)
spinning top test is...
related to timing accuracy
more penetration=
increase kV
max kV is determined by
#/sequence of structures kV passes through
generator w/ highest ripple effect
single phase unit
small focal spot
greater detail and greater heat
fxn of tube housing
reduces leakage
detail is greatest at...
intensity of electrons is greatest
evens out x-ray
compensatory filter
least amount of scatter
highest kV
one xray at 40" and one @ 80"
@80"= 2X distance + 1/4th the intensity (inverse square law)
half value layer (HVL) measured in
mm of Al
primary filter
hardens the beam
primary beam radiation is
bremsstrahlung (braking) (85% of xrays)
penumbra is related to
photoelectric effect
increased density (barium swallow)
creates magnetic field and causes anode to spin
if @ 80kV the film is too light
double the mAs
a result of outer shell electron ejection
compton effect (A-P lumbar scatter)
double the mAs
increases density
anode disc spins at
3400 rpm
advantage of rotating vs. stationary anode
less radiation
less heat generated
increasing grid ratio....
removes more scatter, so we increase mAs
decreasing SID (source image distance/FFD)
inceases magnification
decreases detail
1st xray for medical reasons
mrs. roentgen's hand
1st xray from which university
wurzburg in
3 reasons to use tungsten
high melting poin
high atomic #
high conductivity
mAs tells you
the # of xrays created
optimal mAs
highest current w/ least amount of time
allows for heat transfer from the heat sink to the disc
molybdenum rod
max mAs for a single exposure
600 mAs
do you need more mAs for an obese pt?
increase the time & position the pt. recumbent
how do you warm up the tube?
take a few small exposures
purpose of direct vs. alternating current
3,6 and 12 pulse machines
CT scans
smallest exposure time
1/120 second or 120 pulses/s
advantage of high frequency
50% decrease in radiation.
decrease time, increase detail
advantage of small anode angle
greater detail
if you double the FFD you must alter the
mAs X4 due to inverse square law
thoriated tungston
fxn of focusing cup
focus electrons
primary xray beam created at
increase FFD
decrease magnification
anode disc angle with greates heat exposed
5 degrees of smallest
highest contrast if mAs is the same
the lowest possible kV
the 15% rule is related to
optimum kV is determined by
sequence of structures
generates the highest ripple
single phase, 100%
small focal spot
greater detail
greater heat
detail of the beam is from
longest/widest scale of contrast
higher kV
primary filter
hardens the beam
t/f the 1st nobel prize went to willie roentgen
if the film is too dark...
if the film is too light...
cut mAs in half
double mAs
how is heat created in xray?
electron bouncing creates ions which create heat
where is the primary filter
between the tube and collimator
at what kV are all xrays absorbed by the body
compensating filter
eliminates free radicals (soft radiation)
what does a filter do to a beam?
hardens it
fxn of HVL
decrease strength of beam by 50%
why are lateral ful spine films useless?
too many differences in densities
# of filters in full spine
the problem w/ backscatter is...
operator exposure
compton effect
inner shell
outer shell
at what angle do xrays reflect at?
45 degrees
scatter radiation is always bad
it decreases film quality
the rays do not go in the same direction as the central ray
if you cut the field of view in 1/2...
if you double the field of view...
double the mAs
half the mAs
relationship b/n kV and scatter...
as kV increases scatter increases exponentially
how is scatter affected with obese patients
more scatter
w/ an obese pt...
increase mAs, never kV
fxn of the grid
to absorb scatter so that primary radiation can penetrate
fxn of bucky
to remove gridline artifacts
how is grid ratio measured?
height of strip/distance between strips
what does an increase in grid ratio do?
less scatter and more detail w/ better contrast
as grid ratio increases
both mAs and kV are decreased
who invented the grid?
who invented the bucky?
1st diagnostic xray in the U.S.
dr. frost took of eddy mccarthy