Prime Factors
What are the prime factors technologists have control over?
kVp, mAs, SID
What minimizes magnification?
Decreased OID
When a hypersthenic patient is getting an x-ray, what is something the technologist can do to reduce scatter but maintain all other technical factors?
Increase collimation/decrease FOV
When contrast needs to be adjusted, what technical factor is altered?
kVp
Doses should be kept to the ALARA principle. This acronym stands for what?
As Low As Reasonably Achievable
Increased kVp leads to ________ scatter and _______ contrast.
increased; decreased
What factor can be chosen by the technologist can minimize penumbra?
Small focal spot size
What is considered a predetermined factor that is meant to remove low-energy x-rays from the primary beam?
Filtration
High kVp= ______ contrast
Low kVp= ______ contrast
low/decreased; high/increased
What are the 3 Cardinal Rules, and which is the most important?
Time, distance, shielding. Most important: distance
If optical density needs to be doubled, what factor needs to be adjusted?
mAs
What are the 2 types of geometric factors?
Distortion and detail/resolution
Scatter can change direction and interact with the IR. This can cause ______ on the image.
Fog/noise/decreased contrast
If a technologist takes an x-ray without a grid, and then repeats the x-ray utilizing a 10:1 grid, what happens to the scale of contrast?
Decreases/shortens
If the distance between the source and the technologist is reduced by a factor of 2, what happens to the dose?
Increases by a factor of 4
If an x-ray is taken at 40-inch SID using 65 kVp and 4 mAs, and an additional x-ray needs to be taken after doubling the SID, what new technical factors should be used?
16 mAs
What are the 2 types of visibility factors?
Density/brightness and contrast/gray scale
What is a type of scatter control method that can be used after x-ray interaction with matter?
Air-gap technique or grids
If collimation is increased and the field of view decreases, the scale of contrast is determined to be...
Short scale
If a technologist takes an x-ray using 70 kVp at 8 mAs, but they want to repeat the x-ray reducing the patient's dose and maintaining density, what are the new technical factors?
80 kVp at 4 mAs
If the kVp is increased from 75kVp to 90 kVp, what will happen to contrast, attenuation, dose, penetrability, and scale of contrast?
Contrast= decreases, Attenuation = increases, Dose = increases, Penetrability = increases, Scale = increases/long scale
A technologist takes an x-ray of a 32-year-old patient using 80 kVp at 10 mAs for an abdominal x-ray at 40-inch SID. In order to increase visibility and double the density, what new prime factors can the technologist use in the repeat x-ray?
80 kVp at 20 mAs OR 90 kVp at 10 mAs using 15% rule
List 6 strategies to reduce scatter in the resulting radiograph.
Air gap technique, grids, filtration, low/decrease kVp, increase collimation, decrease field of view
If collimation increases, field of view _________, and, therefore, contrast __________.
decreases; increases
If a technologist is standing 5 feet from the x-ray source and receives 2 mSv in exposure, what is the new dose if the distance is increased to 9 feet?
0.62 mSv