Principles of Radiography

Question 1

When is using Radiography appropriate?

Answer 1

Excellent for imaging bone and gas
Good for soft tissue
Good large scale
Gross structural

Question 2

Limitations of radiography

Answer 2

Radiation risk
Need for restraint
Can’t see internal architecture very well
Still image
2D images

Question 3

ALARP meaning

Answer 3

As Low As Reasonably Practicable
* Dose
* Personnel
* Times
* Distance
* Shielding

Question 4

How does bone appear?

Answer 4

Bright/white
Radiopaque

Question 5

How does fat appear?

Answer 5

Dark grey
Soft tissue opacity

Question 6

How does gas appear?

Answer 6

Black
Radiolucent

Question 7

How does soft tissue appear?

Answer 7

Grey
Soft tissue opacity

Question 8

Radiopaque

Answer 8

○ Most x-rays are absorbed and few penetrate through to image-receptor
○ Appears white
○ E.g. metal and bone

Question 9

Radiolucent

Answer 9

○ Few x-rays are absorbed, most penetrate through to image-receptor
○ Appears black
○ E.g. gas
○ Radiopaque

Question 10

Which side of the image is cranial?

Answer 10

Left

Question 11

Which side of the image is caudal?

Answer 11

Right

Question 12

Most important safety aspects

Answer 12

Never place your hand in the primary beam
Never enter controlled area without PPE
Use vertical beam where possible
Avoid manual restraint

Question 13

Properties of X-rays

Answer 13

• Short wavelength
• High Energy
• Transverse wave
• Requires high voltage to produce X-Rays
• Travel in a straight line
• No charge
• Can lead to ionisation
  ○ Damaging to living tissue
• Can cause some substances to fluoresce
• Penetrate all matter to some degree

Question 14

Production of X-rays

Answer 14

Cathode generates stream of electrons
Electrons hit atoms and result in X-rays being released

Question 15

Quality

Answer 15

Penetrating power of beam

Question 16

Intensity

Answer 16

Amount of radiation in beam

Question 17

What does increased kV do?

Answer 17

Increased quality and intensity
* Increased electron acceleration
* Increased energy of electrons
* More x-rays produced
* Increased penetrating power
* More radiation in beam

Question 18

What does increased mA do?

Answer 18

Increased quality only
* Increased tube current
* More electrons produced
* More x-rays produced
* Energy is unchanged
* Increased penetrating power

Question 19

mAs

Answer 19

Measure of number of x-rays produced

Question 20

kV

Answer 20

Acceleration of electrons

Question 21

Pink Camels Collect Extra Large Apples

Answer 21

Positioning
Centring
Collimation
Exposure
Labelling
Artefacts

Question 22

Positioning

Answer 22

• Part of interest close to image receptor as possible
• Part of interest parallel to image receptor
  ○ If incorrectly positioned, can distort image

Question 23

Centring

Answer 23

Centre primary beam over area of interest

Question 24

Collimation

Answer 24

• Collimation reduces production of scattered radiation
• Collimate beam to minimum size necessary

Question 25

Exposure

Answer 25

Use correct exposure factors
under/over exposure will affect image

Question 26

Labelling

Answer 26

• Always expose side marker
• Patient details are entered into PC software
• Lying in right lateral recumbency = R marker

Question 27

Artefacts

Answer 27

• Appearances on image that do not correspond to structure of patient
• Check there is nothing that could cause artefact
  ○ Sandbags
  ○ Foam wedges
  ○ Drip lines
  ○ Collars

Question 28

What does an underexposed radiograph look like?

Answer 28

Grainy
Quantum mottle