Term
purposes of beam restriction |
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Definition
limit patient exposure reduce amount of scatter produced in patient improve image quality |
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Term
as beam restriction ___, field size and patient dose _____ |
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Definition
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Term
with reduced scatter, radiographic contrast ____ |
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Definition
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Term
most important characteristic of image quality |
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Definition
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Term
two major factors that create scatter radiation |
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Definition
high kVp volume of tissure irradiated |
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Term
types of beam limiting devices |
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Definition
aperature diaphragm cones and cylinders collimator PBL |
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Term
bottom shutters of collimator |
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Definition
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Term
upper shutters of collimator |
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Definition
reduce amount of off focus radiation |
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Term
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Definition
Positive Beam Limiting device automatic colimators are adjusted by tube head once IR is placed in bucky can be overridden |
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Term
as filtration is _____, so is beam quality, but quantity is ___ |
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Definition
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Term
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Definition
inherent added compensating |
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Term
inherent filtration provided by |
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Definition
thickness of glass envelope dielectric oil coolant port or glass window of housing |
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Term
most inherent filtration comes form |
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Definition
port/glass window of housing .5-1.0 mm Al/Eq |
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Term
inherent filtration in mammography tubes |
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Definition
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Term
mammography tubes are made of |
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Definition
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Term
functions well as a low energy absorber, atomic number of 13 |
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Definition
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Term
two sources of added filtration |
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Definition
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Term
average thickness of collimator device |
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Definition
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Term
types of compensating filters |
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Definition
wedge trough/bilateral bow-tie cone step-wedge |
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Term
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Definition
= inherent filtration (.5mm) + added filteration (added filter of 1.0mm and mirror 1.0mm) =2.5mm Al |
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Term
doesnt include any compound or compensating filters |
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Definition
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Term
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Definition
requires minimum total filtration levels |
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Term
filtration requirement for <50 kVp |
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Definition
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Term
filtration requirement for 50-70 kVp |
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Definition
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Term
filtration requirement for >70 kVp |
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Definition
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Term
filtration reduces patient dose by |
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Definition
eliminating low energy photons from primary xray beam |
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Term
when filtration in increased, ___ must also be increased to maintain density |
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Definition
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Term
any significant increase in filtration (1.0 mm Al/Eq) will have an overal _____ |
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Definition
entrance skin exposure reduction effect |
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Term
point of diminishing returns where reduction in ESE does not warrant tube loading increase |
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Definition
beyond 3.0 mm Al/Eq of filtration |
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Term
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Definition
measures quality of xrays represents thickness of absorbing material to reduce xray intensity to half its original value |
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Term
result of low energy attenuation shifts xray emission spectrum to high energy side, resulting in |
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Definition
xray beam with higher energy greater penetrability better quality |
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