VETS 255 Exam 2

What is the effect of patient motion on resolution of the radiographic image?

Causes blurring of any area that is in motion.

What is penumbra?

The blurring around edges of image 

What are three causes of penumbra?

Large focal spot, short SID, increased OFD

What causes this type of distortion?

Magnification

What causes this type of distortion?

Elongation

What causes this type of distortion?

Foreshortening

How can this type of distortion be prevented?

Decrease the distance between the image receptor and area of interest.

How can this type of distortion be prevented?

Keep image receptor parallel to the area of interest.

How can this type of distortion be prevented?

Keep the area of interest parallel to the image receptor.

What is scatter radiation?

The x-rays that bounce off the patient from the primary ray.

What is the most common type of radiation exposure for Vet Techs?

Scatter radiation

What increases scatter radiation?

High kVp

How can we reduce negative effects of scatter?

The use of a grid for measurements over 10 cm

What causes film fog?

Scatter radiation

What effect does it have on the radiographic image?

Appears more black

Does film fog increase or decrease radiographic density and why?

Increases radiographic density because it decreases contrast.

What is the purpose of a grid?

Used to reduce scatter radiation 

How does a grid work?

It absorb scatter x-rays to reduce film fog and improve radiographic contrast 

Why must mAs be increased when using a grid?

So more x-rays can pass through the lead strips and not cause white lines from the grid.

Where must a grid be located to be effective?

Between patient and image receptor 

What is an artifact?

Anything that decreases the quality of a radiograph 

What causes black tree like pattern?

static electricity exposing film

What causes visible grid lines on the entire image?

The grid is not perpendicular to central x-ray of primary beam 

What causes visible grid lines on one end of the image?

The grid not centered with primary beam 

What causes film fog?

Patient motion, increased OFD, decreased SID, large focal spot

What is radiographic detail?

Clear definition

What factors result in a loss of detail?

Patient motion and Penumbra effects

How do you correct an under or overexposure image?

Increase or decrease the kVp by 15%