FINALS Flashcards
it contains only specificvalues
discrete spectrum
it contains all possible values
continuous spectrum
factors affecting x-ray emission
effect of mA and mAs
effect of kVp
effect of added filtration
effect of target material
effect of voltage wavefrom
what happens if the right spectrum is farther to the right
higher energy/quality of x-ray beam
what happens if the area under the curve is large
higher intensity/x-ray quantity
distance of 1 crest to another
wavelength
height of crest, 1/2 the range from crest to valley over which the sine wave varies
amplitude
if we increase kVp by 15%, what happens to mAs
increase by 2
5 voltage waveforms
half-wave rectified, full-wave rectified, three-phase six pulse, three-phase twelve pulse, high frequency waveform
an increase in current results in
increased quantity, no change in quality
an increase in voltage results in
increased quantity and quality
an increase in added filtration results in
decreased quantity and increased quality
an increase in target material results in
increased quantity and quality
an increase in voltage ripple results in
decrease quantity and quality
x-ray quantity is also called
x-ray intensity/radiation exposure
it is the number of x-rays in the useful beam
x-ray quantity
x-ray quantity can be measured in
R, mGya, mGya/mAs, mR/mn, mR/mA
factors affecting x-ray quantity
mAs, kVp, distance, filtration
when this is doubled, number of electrons striking the tube target is doubled, therefore, the number of x-rays emitted is doubled
mAs
if this is doubled, x-ray intensity would increase by a factor of four
kvp
this results to x-ray beam reduces patient dose and reduce number of low-energy x-rays that reach the patient
filtration
disadvantage of filtration
reduced image contrast
these contribute nothing to radiograph; it does not penetrate the patient but only increases patient dose as it is absorbed by superficial tissues
low-energy x-rays
the ability of x-ray beam to pass through tissue
penetrability
high penetrability is called as
high quality x-rays
low penetrability is called as
low quality x-rays
x-ray quality is identified numerically by
HVL
it is the reduction in x-ray intensity resulting from absorption and scattering, best method for specifying x-ray quality
half-value layer
usual material of filtration as it is efficient in removal of low-energy photons from x-ray beam
aluminum
an important quality control test to measure whether or not there is sufficient filtration in the x-ray beam to remove low energy radiations
half value layer
a diagnostic x-ray beam usually has an hvl in the range of
3-5 Al or 3-6 cm of soft tissue
it calculates reductions of exposure and quality of x-ray beam
half value layer
factors affecting x-ray quality
kVp, filtration,
an increase in kVp results in
increased beam quality, quantity and hvl
increased mAs results in
no effect in quality, increased in quantity
increased distance results in
no effect in quality, decreased quantity
its primary purpose to an x-ray beam is selectively to remove low-energy x-rays that have little chance of getting to the IR
filtration
types of filtration
added, inherent
located in glass enclosure and amount of filtration is provided by x-ray tube
inherent filtration
a special purpose of tube such as used in mammography and made up of beryllium that has inherent filtration of
.1 mm Al
inherent filtration of a general purpose x-ray tube is
.5 mm Al
thin sheet of aluminum positioned between the protective x-ray tube housing and x-ray beam collimator is its usual form
added filtration
thickness of added filtration
1-3 mm Al
usual 2 sources that totals to 2-3 mm Al
first and second
1-2 mm sheets of Al that are permanently installed in the part of x-ray tube housing, between the housing and collimator
first
1 mm Al silver surface of the mirror in the collimator
second
compensating filter
trough filter, bow-tie, step wedge, wedge, cconic filters
compensating filter used for chest radiography
trough filter
compensating filter used for ct and shape of head
bow-tie
compensating filter used for long secction of anatomy such as translumbar, femoral arteriography, venography
step wedge
compensating filter used for foot
wedge
compensating filter used for digital fluoroscopy
conic filters
