Chapter 8, 9 and 11 in Bushong, 10th Edition (X-Ray Emission, X-Ray Interaction With Matter, & Control of Scatter Radiation)
X-ray intensity, x-ray quantity and radiation exposure are the same terms and are measured in what?
mGya - milligray in air (formerly milliroentgen - mR)
X-ray quantity is
The number of x-rays in the useful beam
Most general radiography tubes, when operated at 70 kVp, produce x-ray intensities of ____ uGya/mAs at a ____ 100cm SID
Image contrast is ____ as kVp is ____
Added filtration to the useful x-ray beam reduces what?
X-ray beam hardening increases the number of ____ by removing the ____
High energy x-rays, low energy x-rays
The penetrability of an x-ray beam is called the ____
Penetrability is the ____
Ability of an x-ray beam to pass through tissue
X-rays of any given energy are more penetrating in material of ____ than in material of ____
low atomic number, high atomic number
Attenuation is the ____
Reduction in x-ray intensity
Attenuation is the result of ____
Absorption and scattering
The quality of x-rays is measured by the ____
The HVL of an x-ray beam is the ____
Thickness of absorbing material necessary to reduce the x-ray intensity to half its original value
How is the HVL theoretically determined?
Experimentally, using an x-ray tube, a radiation detector, and a graded thickness of filters, usually Aluminum
How is the HVL mathematically determined?
On a plot, find the number that is half the radiation dose of the dose from the filterless exposure. Draw a horizontal line from that number until it intersects the curve. Draw a line downward to the x-axis. Where it hits on the x-axis is the HVL
X-ray beam quality can be identified by kVp or filtration, but ____ is most appropriate
An increase in mAs has ____ effect on x-ray quality, and ____ x-ray quantity
An increase in kVp ____ x-ray quality, and ____ x-ray quantity
An increase in distance has ____ effect on x-ray quality, and ____ x-ray quantity
An increase in filtration ____ x-ray quality, and ____ x-ray quantity
What are the two factors that affect x-ray quality?
kVp and filtration
What are the three types of filtration?
Inherent filtration, added filtration, and compensating filtration
What is inherent filtration?
The glass or metal enclosure of an x-ray tube that filters the emitted x-ray beam and is usually 0.5mm Al equivalent
With age, inherent filtration tends to ____ due to ____
Increase, tungsten deposits
What is added filtration?
A thin sheet of Al positioned between the protective x-ray tube housing and the x-ray beam collimator
Added filtration ____ the HVL
Added filtration attenuates a greater number of ____ energy x-rays than ____ energy x-rays
The collimator contributes an additional ____ equivalent added filtration
What is a compensating filter?
A filter that compensates for differences in subject radiopacity
When is a compensating filter used?
When a body part is examined that varies greatly in thickness or tissue composition
Where is the thick portion of a compensating filter positioned?