POI Flashcards
RALATIONSHIP OF SID AND DENSITY
IR
What is the reason why Sid and Density IR?
s SID increases, the intensity of the x-ray beam reaching the image receptor decreases, resulting in lower density
formula density maintinance
mas1/mas2 = (sid1/sid2)2
an increased in OID MAKES THE DENSITY____
decrease
reason for decrease in density when OID increase
. As the exit radiation continues to diverge, less overall density of the x-ray beam will reach the image receptor
grid is usually made up of
aluminum, plastic, carbon
a device that is placed between the patient and image receptor to absorb scatter radiation exiting the patient
Grid
RS BETWEEN GRID AND DENSITY
IR
EQUVALENT OF 5:1
2
6:1
3
NO GRID IS EQUAL TO
1
8:1
4
12:1
5
16:1
6
The more sensitive the film-screen system is to radiation, the___the speed
faster
The greater the speed, the ____ the density produced for a given exposure technique.
greater
RS OF SPEED AND DENSITY?
DR
What technichal factor will you change if you need to maintian density
mAs
Is defined as a decrease in the number of transmitted photons that reach the image receptor because of some misalignment of the grid.
Grid Cutoff
The primary radiographic effect of grid cutoff is
reduction in the number of photons
be used to determine the adjustment in mAs needed when changing from using a grid to non-grid (or vice versa)
Grid conversion factor (GCF), or Bucky factor
types of grids
- Wafer Grid
2 Grid Cassette
3 Grid Cap
matches the size of cassette and is use by placing it on top of the image receptor.
- Wafer Grid
is an image receptor that has a grid permanently mounted to its front surface.
- Grid Cassette
