Scattered Radiation and Grids

Lays down a “blanket” of evenly distributed exposure

scatter

Adds a fixed amount of exposure to every tissue in that area

scatter

Scatter _______ subject contrast

reduces

If all other factors remain ______, the addition of scatter can add to the total exposure reaching the IR

constant

An image can also can have excessive amounts of scatter, but can also be ________

Over or underexposed

underexposed

if you’re using a grid should you use more or less technique

more

How big should the body part be measured to use a grid

13 cm

What is canting

angling of the lead strips to match the isotropic properties of the beam

list 3 factors that can cause scatter

high lvls of kvp

large field size

large body part thickness of soft tissue

After scatter radiation is produced only practical method of reducing it before it hits the IR is _______

grids

What technique uses OID to deflect scatter off of the IR & therefore increase image contrast

air gap technique

known as "poor man's grid"

air gap technique

list 2 disadvantages when using the air gap technique

magnification

blur

is scatter and blur the same?

no

As you increase OID what happens to receptor exposure

Why?

decreases; scatter diverges off of the plate

Does scatter undercut the edge of an image

NO

T/F: Reduction of scatter by a grid does not improve sharpness of detail

T: increases the overall visibility/detail

Does scatter change the overall geometrical integrity

no

Is penumbra greater on the cathode or anode side

cathode

list 3 factors that affect penumbra

sid

oid

size of focal spot (small is better)

Who invented the grid in 1913

Gustav Bucky

Grid reduces scatter that has already been

produced

What do grids restore from the remnant x ray beam

subject contrast

What are the alternating strips made of in a grid

lead foil

What are the strips separated by in a grid

radiotransparent interspace material

Were stationary grids practical?

Why or why not

no; pattern of lead strips were seen on the image

• represented as noise and loss of some information