Term
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Definition
removal of low energy xrays from the useful beam with aluminum or other metal
primary purpose is to remove low energy xrays that have no chance of getting to the film |
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Term
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Definition
| the thickness of absorber or filter that will reduce an xray beam to half its original value/intensity |
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Term
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Definition
the penetrability or penetrating power of an xray beam
high quality/hard xrays
low quality/soft xrays |
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Term
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Definition
has more effect than any other factor on exposure because it affects beam quality and also influences beam quantity
controls the scale of contrast on the finished radiograph |
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Term
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Definition
| as kVp is increased, so is xray beam quality as well as the half value layer |
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Term
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Definition
| lower subject contrast and long scale contrast |
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Term
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Definition
| high subject contrast and short scale contrast |
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Term
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Definition
High kVp
Equals
Long scale
Low contrast |
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Term
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Definition
low kVp
equals
short scale
high contrast |
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Term
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Definition
| as filtration is ______, beam quality increases but quantity decreases |
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Term
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Definition
removes low energy photons
overall, xray photon energy is increased while quantity is decreased
patient dose reduced |
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Term
| absorption characteristics |
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Definition
absorbs all low energy radiation
absorbs no high energy radiation |
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Term
| high atomic number desirability |
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Definition
| increases photoelectric absorption of low energy photons |
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Term
| materials used as xray filter |
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Definition
aluminum
copper
gadolinium
holmium |
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Term
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Definition
filtration that is a result of the composition of the tube and housing
-thickness of glass envelope
-dielectric oil coolant
-port or glass window of the housing** |
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Term
| special purpose tubes (mammography) |
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Definition
very thin xray tube windows
made of beryllium |
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Term
|
Definition
placed between the protective tube housing and the external housing or collimator
has two sources that totals 2 and 3 mm sheets of aluminum equivalent |
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Term
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Definition
used to compensate for differences in subject radiopacity
used to even out widely differing tissue densities |
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Term
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Definition
used to compensate for differences in subject radiopacity
used to even out widely differing tissue densities |
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Term
|
Definition
type of compensating filter
used to radiograph body parts that vary considerably (foot) |
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Term
| trough filter (bilateral wedge) |
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Definition
type of compensating filter
used mainly for chest radiography |
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Term
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Definition
| used in some CT scanners to compensate for shape of head/body |
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Term
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Definition
| convex or concave and applied in digital flouroscopy |
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Term
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Definition
adaptation of wedge filter
used in some special procedures where long sections of anatomy are radiographed with separate films |
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Term
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Definition
| an aperature diaphragm that flares with upper diameter smaller than bottom flared end |
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Term
|
Definition
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Term
|
Definition
most commonly employed beam restrictor in radiography
permits an infinite number of field sizes using only one device
provides light source for radiographer |
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Term
|
Definition
crosshairs
two black lines drawn on plastic sheet attached to collimator |
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Term
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Definition
controls density
too high, lands on shoulder of characteristic curve
too low, lands on toe |
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Term
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Definition
affects both the amplitude and position of xray emission spectrum
affects both quality and quantity |
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Term
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Definition
| increasing target atomic number enhances the efficiency of xray production and energy of characteristic and brems xrays |
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Term
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Definition
| the range of ODs from the whitest to blackest part of the radiograph |
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Term
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Definition
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Term
|
Definition
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Term
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Definition
| a change of approximately _____ in kVp is required to usually affect the scale of contrast in the 50-90 kVp range |
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Term
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Definition
| at lower kVp, a ___ may be sufficient |
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Term
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Definition
| at higher kVp, a ___ may be required |
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Term
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Definition
used to change scale of contrast from long to short, vice versa
change the kVp by 15% while changing the mAs by one half or double |
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Term
|
Definition
a smaller technique compensation for a change in contrast scale
and increase of 5% in kVp may be accompanied by a 30% reduction in mAs to produce the same OD |
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Term
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Definition
| results in shorter scale of contrast compared with non screen |
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Term
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Definition
also known as recorded detail or spatial resolution
the sharpness of appearance of small structures
evaluated by recorded detail and visibility of image detail |
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Term
| factors controlling detail |
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Definition
Focal spot size (controls penumbra)
SID
OID
Collimation
Grids
Motion |
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Term
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Definition
controls penumbra
major controller of image resolution
as FS decreases, penumbra decreases, therefore increasing resolution |
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Term
|
Definition
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Term
|
Definition
affects recorded detail
fails to permit enough time for a well defined image to form
voluntary, involuntary, equipment |
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Term
| methods of reducing motion |
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Definition
communication
exposure time reduction
immobilization |
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Term
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Definition
| to produce the sharpest image detail, one should use the ___ appropriate focal spot, the _____ SID and place the part as close to the IR as possible |
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Term
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Definition
| the only type of size distortion with film/screen radiography possible |
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Term
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Definition
| the greater the ____, the smaller the magnification |
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Term
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Definition
| OID must be ____ to decrease magnification |
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Term
| calculating size distortion |
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Definition
M= SID/ SOD
m is magnification factor |
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Term
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Definition
| two types: elongation and foreshortening |
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Term
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Definition
| anatomical part appears bigger than normal due to poor alignment of IR or xray tube |
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Term
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Definition
| anatomical part appears smaller than normal due to poor alignment of the anatomical part |
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Term
| changes in the tube angle |
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Definition
| cause elongation but never foreshortening |
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Term
| ways to minimize misrepresentation |
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Definition
proper alignment of
CR
anatomical part
IR |
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