Ch. 6 Generators, Beam Restriction, PT Factors Flashcards
A larger field size is ______ collimation.
Decreased
A smaller field size is _________ collimation.
Increased
A larger field size causes ________ radiation to be produced.
More scatter
An increased amount of scatter reaching the IR results in
Less radiographic contrast
The decreased amount of scatter radiation reaching the image receptor results in __________, BUT it requires an increase in ________.
Higher radiographic contrast, mAs
The effect of collimation is greatest when imaging ______ anatomic areas, performing w/o a grid, and using high kVp.
Large
What are the functions of a generator?
- Allows the current to flow into the x-ray tube
- Produces x-rays when electrical current is applied.
In radiography, you want a _____ or _______ generator.
3 phase or high frequency
Generators are periodically calibrated to ensure consistent radiation output.
…
T or F- Radiographers do not need to be aware of which type of generator or equipment is used because fixing the machines are out of our scope of practice.
F - must be aware of the type of generator and equipment used in order to properly set a technique
Increased tube filtration= _______ ratio of high penetrating x-rays to low x-rays
Increased
Increased tube filtration = ______ radiation quantity, _______ average energy of beam
Decreased, increased
The use of compensating filters requires an increase in _______ to maintain the overall exposure to the IR.
MAs
What does part thickness affect?
- Beam attenuation
- Exposure reaching image receptor
- Scatter production and image contrast
Because x-rays are exponentially attenuated, every change in pt thickness of __________ then MAs should be adjusted by a factor of 2.
4-5cm or 1 1/2-2in.
In order to maintain exposure, you must ____ mAs fo a larger patient
Increase
In order to maintain exposure, you must ______ mAs for a thinner patient
Decrease
Name the four body habitus
Hyper, hypo, sthenic, Asthenic
What is the function of a compensating filter?
Added filtration that is placed in the primary beam to produce a more uniform exposure to the IR.
How is filtration measured?
MmAl (any tube that operates over 70kvp must have a total filtration of 2mmAl?)
