1 - Introduction to Radiology

Question 1

what is a radiograph and how is it produced on a film or digitally? (what do they x-rays interact with in both?)

Answer 1

a radiograph is an image produced by X-rays passing through an object, and interacting with the emulsion on a film.
if a digital image is formed, the x-rays interact with a sensor or phosphor plate

Question 2

why are radiographs useful?

Answer 2

they allow us to look inside the body, particularly at the mineralized tissues
other advanced imaging techniques let us look at the soft tissues as well

Question 3

within an atom: what is the charge of the following?
proton
neutron
electron

Answer 3

• positive
• neutral
• negative

Question 4

electrons: how do they move?
what is the zone between shells called?
what is required to remove electron from atom?

Answer 4

• they move in predetermined shells with different energy levels
  each shell has a maximum number of electrons
  e.g. K =2, L =8, etc
• forbidden zone
• energy, needs to overcome the electron’s binding energy which keeps it in its shell

Question 5

what is an isotope?

Answer 5

atoms with the same amount of protons (Z) but different amount of neutrons (N)

Question 6

what is a radioisotope?

Answer 6

isotopes with unstable nuclei which undergo radioactive disintegration

Question 7

alpha particle:
what does it consist of? 
size? 
charge? 
speed?
penetration?
energy?
damage potential?

Answer 7

• a helium nucleus that is made up of 2 protons and 2 neutrons
• large
• positive
• slow
• 1-2mm in tissue
• 4-8 MeV
• extensive ionisation

Question 8

beta particle:
what does it consist of? 
size? 
charge? 
speed?
penetration?
energy?
damage potential?

Answer 8

• electrons
• small
• negative
• fast
• 1-2 cm in tissue
• 100keV - 6 MeV
• ionisation

Question 9

gamma rays:
what does it consist of? 
size? 
charge? 
speed?
penetration?
energy?
damage potential?

Answer 9

• electromagnetic radiation
• no size
• no charge
• very fast
• can pass through tissue
• 1.24 keV - 12.4 MeV
• ionisation

Question 10

x-rays used in dentistry:
how do they occur?
similar to which type of rays, but how are they different?
particle size? charge? speed? potential for damage?

Answer 10

• do not occur naturally
• similar to gamma rays, but without as high energy values
• not particulate, no charge, very fast
• ionisation