IP
it doubles
what is the formula for grid ratio?
Grid ratio= Height (h) / Distance (d)
Why are grids used?
to remove scatter radiation
what is the grid conversion factor for a non-grid?
1
what is the grid conversion factor for a 16: 1 grid ratio?
6
what happens to receptor exposure if kVp is decreased 15%
it is cut in half
what do grids act as?
beam attenuators
what effect does removing scatter have on the image?
reduces fog and improves image quality (contrast)
what is the grid conversion factor for a 5:1 grid ratio?
2
what is the grid conversion formula?
1. mAs1/mAs2 =conversion factor 1/conversion factor 2
2. old mAs/new mAs = old grid/new grid
on the exam, if a question says "maintain exposure, what should you adjust?
adjust mAs
if grid ratio increases and no technique change is made, what happens to receptor exposure?
RE decreases.
what happens to patient dose when mAs is increased to compensate for a grid?
patient dose increases
what is the grid conversion factor for a 6:1 grid ratio?
3.
what type of factor is filtration?
photographic factor
on the exam, if a question states "sufficient" what should you adjust?
leave mAs alone
How do you maintain receptor exposure when using a grid?
increase mAs
what does "H" stand for in the grid ratio formula?
height of lead strips
what is the grid conversion factor for a 8:1 grid ratio?
4
what is the purpose of filtration?
acts as a beam attenuator, decreases skin exposure to patient
what type of factor are grids?
photographic factor
what determines how much mAs must be increased when using a grid?
the grid ratio
what does "D" stand for in the grid ratio formula?
distance between the lead strips
what is the grid conversion factor for a 10:1 and 12:1 grid ratio?
5
what happens to receptor exposure as filtration increase?
RE decreases