Principles of Imaging

Question 1

Outline the production of a radiograph.

Answer 1

Electrons are produced by a heating filament. These are then fired at a tungsten block. This excited the tungsten atoms leading to the emission of X-rays. These penetrate tissue and get absorbed to different degrees, producing the desired image.

Question 2

Attenuation

Answer 2

Stopping X-ray photons

Question 3

Complete exposure

Answer 3

No attenuation, black

Question 4

Unexposed

Answer 4

Full attenuation, white

Question 5

Outline the five basic radiographic opacities.

Answer 5

Black - air, Dark grey - fat, Mid-grey - soft tissue/ fluid, Light grey - mineral (bone), White - metallic

Question 6

Apparent opacity of materials on radiographs depends upon..

Answer 6

Atomic number, physical density, thickness

Question 7

Collimation

Answer 7

A scatter plate allows viewing of all four edges of the radiograph

Question 8

Outline the mnemonic approach to assessing radiographs.

Answer 8

Alignment, bones, cartilage/joints, devices, everything else (soft tissue)

Question 9

Identify the radiographic signs which should always be checked when assessing a lesion.

Answer 9

Number, size (measure), shape, location, opacity

Question 10

What is the mass effect?

Answer 10

Masses lead to disruption of normal anatomy

Question 11

Effacement

Answer 11

Unable to see the edge of a structure