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chap 26 density


What is the human visibility density range? .25-2.50
What is brightness? monitor control function that can change the lightness and darkness of the image on a display screen. Luminosity intensity.
What is the window level? Digital post processing that produces changes in brightness. Controls brightness.
What is the controlling factor for density/IR exposure? mAs
Density and time have what relationship? Directly proportional.
The factor that determines the total quantity of x-rays produced in a beam is the? mAs
The length of x-ray exposure is determined by the? time
Time controls or influences what? Density.
Density and mAs have what relationship? Directly proportional.
mA controls/influences what? Density
What factor is the amount of current in the x-ray tube at the time of exposure? mA. Amperage is the unit of current.
What does kilovoltage change? Contrast.
To cause a visible shift in denity, what percent of mAs or influencer should be used? 30%
mAs changes generally go in increments of what? doubles or halves
Kilovoltage controls the average ____________ produced at the anode target. energy of the x-ray photons
Why does kVp have an impact on density/IR exposure? kV alters the intensity of the beam when mAs and other factors stay the same, therefor both the quantity and the quality of the x-ray beam vary significantly with kV changes.
The 15 percent rule is used for what? Maintaining the same density/exposure when kV changes.
a 15% increase in kV causes _____ exposure to the IR. Doubling
a 15% decrease in kV would _____ the IR exposure. Half.
A single-phase waveform has lower average photon energy, resulting in what kind of exposure? A less dense IR exposure
Anode heel effect alters what? The radiation intensity, so the density.
What does the inverse square law express? the change in intensity when the distance changes.
According to the inverse square law, as distance increases, radiation intensity... and IR exposure/density decreases in 4 directions.
According to the exposure maintenance formula… To maintain IR exposure, what must happen when distance increases? mAs must increase
How does beam restriction affect density? Collimating or reducing the beam size reduces the # of photons, this reduces the amount of scatter radiation.
What is the relationship between tissue and density? Inverse.
As relative speed (RS) increases, what happens to the amount of exposure required to maintain density? it decreases.
How does the inverse square law differ from the exposure maintenance formula? the inverse square law expresses intensity change. ex) distance increases, intensity and exposure decrease. The maintenance is reversed. ex) distance increases, mAs must increase.
What happens to density if you increase filtration? Inverse relationship. Adding filtration absorbs more low quality photons, resulting in a better quality beam and decreasing exposure-decreasing density.
What happens to density if you decrease the grid ratio? Density increases.
If you decrease the OID what happens to density? Increases.
Increasing beam restriction/collimation does what to density? Decreases density.
Created by: Zoest35