Radiography

Question 1

What are the roentgen signs?

Answer 1

Number 
Location 
Size
Shape
Margination 
Radiopacity 
(Internal architecture)
(function)

Question 2

When can you not GA a patient for radiographs?

Answer 2

If you are doing an oral barium contrast study

Question 3

How can you decrease movement blur?

Answer 3

Increase mA and decrease the exposure time

Question 4

How can you tell if an image is perpendicular?

Answer 4

The caudodorsal rib heads will be superimposed

Question 5

How many unexposed boarders should a cassette have?

Answer 5

4

This is described as 0/25/50/75/100% of each 4 borders)

Question 6

How do grids work?

Answer 6

Consist of strips of plastic and lead that filter out x-ray photons that are not passing in a straight line
This reduced the scattered radiation reading the x-ray cassette

Question 7

When should you use a grid?

Answer 7

Body regions greater than 10-15cm thick

Question 8

What must you compensate with when using a grid?

Answer 8

The grid absorbs a proportion the primary beam so you must increase the exposure (higher mA’s) This is defined as the ‘grid factor’ and can be x2 or x3

Question 9

What do negative contrast media look like?

Answer 9

Low density - low radiographic opacity so have a radiolucent appearance eg. gas

Question 10

What do positive contrast media look like?

Answer 10

high density - high radiographic opacity so have a radiopaque appearance eg. barium

Question 11

Before doing a contrast study what should you do first?

Answer 11

Take enough plain radiographs

Question 12

Where are negative contract medias used?

Answer 12

Mostly used in the bladder and GI tract

Question 13

What are the advantages and disadvantages of negative contrast media?

Answer 13

A: cheap, quick and convenient. Relatively safe

D: Poor mucosal detail, Slowly eliminated from the body (can confuse further studies) , theoretical risk of air embolus (Co2 is more soluble and therefore safer)

Question 14

Where is barium sulphate used in contrast studies?

Answer 14

GI tract administered as a paste or mixed with food

Question 15

What are the advantages and disadvantages of barium sulphate as a contract media?

Answer 15

A: Low toxicity, inert, excellent mucosal details, relatively cheap

D: care with aspiration (not use under GA), Irritant if it enters the body cavity (don’t use if suspect perforation

Question 16

When are water soluble iodine preparations used as contrast media?

Answer 16

Imagine the CVS, urinary tract, joints, salivary glands, tear ducts, sinuses, Gi tract and myelography

Question 17

What are the types of water-soluble iodine contrast media available?

Answer 17

Ionic: suitable for IV but not myelography
Non-ionic: Suitable for myelography and any other use (reccomened as it has fewer side effects)
GI preparations

Question 18

What are the advantages and disadvantages of water soluble iodine preparations as a contract media?

Answer 18

A: Versatile and rapidly absorbed if it leaks into body cavities
D: Hyperosmolar (unpleasant side effects if conscious eg. nausea/vomiting), Irritant if injected perivascularly, large does are toxic, contraindicated Iv if the patient is hypovolaemic/hypotension and cardiac or renal failure

Question 19

What are the A&D of CT and MRI?

Answer 19

A: avoids superimposition, good for surgical planning
D: animal needs restraint for long periods of time and costly

Question 20

Where is CT appropriate?

Answer 20

NAsal cavities 
Middle ear 
Some joints 
Pharynx, lungs
Thoracic and abdominal masses

Question 21

Where is MRI appropriate?

Answer 21

Nervous system
Middle ear
Soft tissue masses