Grids Textbook Questions (RADS 230)

The projected shape of the unrestricted primary beam is...

Circular

One purpose of beam-restricting devices is to _____ by changing the size and shape of the primary beam.

decrease scatter and radiation produced

The most effective type of beam-restricting device is the _______________.

collimator

Of the beam-restricting devices listed, which two are most similar to one another? (cone, aperature diaphragm, cylinder, collimator)

cone & cylinder

The purpose of automatic collimation is to ensure that_______

the field size does not exceed the IR size

When making a significant increase in collimation...

mAs should be increased

Which one of the following increases as collimation increases?

Contrast

Which of the following statements are true for positive beam limiting devices?

- the automatically limit the size and shape of the primary beam to IR

-In newer DR units, may automatically restrict the beam to anatomic area selected

The purpose of a grid in radiography is to:

increase image contrast

Grid ratio is defined as the ratio of the...

height of the lead strips to the distance between them

compared with parallel grids, focused grids...

allow more transmitted photons to reach the IR

With which one of the following grids would a convergent line be formed if imaginary lines from its grid lines were drawn in space above it?

linear focused

If 10 mAs is used to produce a particular level of exposure to the IR without a grid, what value of mAs would be needed to produce that same level of expsure using a 12:1 grid?

50 mAs

With exposure technique compensation, which of the following would result in the greatest radiation exposure to the patient?

12:1 grid ratio

off-focus grid cutoff occurs by using an SID that is not ___

within the focal range of the grid

The type of motion most often used for moving grids today is:

reciprocating

A grid should be used whenever the anatomic part size exceeds

10 cm

With radiographic exposures that do not use a grid, which of the following is not an adavantage if scatter correction software?

improved spatial resolution

the air gap technique uses an increased ___ instead of a grid

OID

___________ improves the visible appearance of a radiographic image without the use of a grid

grid replacement software

Following exposure technique adjustment, which of the following would NOT decrease patient radiation exposure using a DR receptor?

using a cross-hatched grid