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30 Cards in this Set
- Front
- Back
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kilovoltage (kV) |
controls the energy or penetrating power of the x-ray beam |
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milliamperage (mA) |
controls the quantity of number of x-rays produced |
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exposure time (ms) |
controls the duration of the exposure usually expressed in milliseconds |
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Film-based radiographic images are evaluated on the basis of four quality factors, the four quality factors are; |
Density Contrast Spatial resolution Distortion |
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Density |
amount of "blackness" on the processed radiograph |
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Primary controlling factor of density |
mAs |
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Source image receptor distance (SID) |
the distance of the x-ray source from the IR
(if the SID is doubled at the IR, the intensity of the x-ray beam is reduced to 1/4th which then reduces radiographic density to 1/4th.)
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When film images are underexposed or overexposed a general rule sates that a minimum change in mAs of _______ is required to make a visible difference in density. |
25%-30% |
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the intensity of radiation emitted form the cathode end of the x-ray tube is greater than the emitted at the anode end |
anode heel affect |
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The patient should be positioned so that the ________ portion of the part is at the cathode end of the x-ray tube and the ________ part is at the anode end. |
thicker;thinner |
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These filter out a portion of the primary beam toward the thin or less dense part of the body that is being imaged |
compensating filters |
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Filter primarily used for AP foot, AP thoracic spine, and axiolateral projection of the hip |
wedge filter |
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Filter primarily used for chest imaging |
trough filter |
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Filter primarily used for shoulder and upper thoracic spine |
boomerang |
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The difference in density between adjacent areas of a radiographic image |
radiographic contrast |
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Primary controlling factor for contrast |
kV
High kV results in lower contrast
15% increase in kV will increase film density, similar to doubling the mAs. |
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Radiation that has been changed in direction and intensity as a result of interaction with patient tissue |
scatter radiation |
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The recorded sharpness of a structure |
spatial resolution |
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The unsharp edges of objects in a projected image |
penumbra |
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The greatest deterrent to image sharpness as related to positioning is; |
motion; voluntary and involuntary |
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Use of a small ________, an increase in _______, and a decrease in ________ results in less geometric unsharpness and increased resolution. |
focal spot;SID;OID |
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___________ magnification occurs at a greater SID than at a shorter SID |
Less |
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Standard SID for most skeletal radiographic examinations |
minimum of 40 inches with 44-48 inches recommended
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The ______ the object being radiographed is to the IR, the less are the magnification and shape distortion and the better is the resolution |
closer |
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Refers to the alignment or plane of the object that is being radiographed in relation to the plane of the image receptor |
object image receptor alignment |
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The least possible distortion occurs here |
central ray |
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For most projections, this aligned perpendicular or 90 degrees to the plane of the IR |
CR angle |
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For digital radiography, the numeric value that is representative of the exposure that the IR has received is the __________ |
exposure indicator |
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Happens in which the signal (mAs) is greater than the noise, so that the low-contrast soft tissue structures can be demonstrated |
high signal-to-noise (SNR) ratio desirable |
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A low signal (low mAs) with accompanying high noise obscures soft tissue detail and produces grainy or mottled image |
Low SNR undesirable |
