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