Introduction to Dental radiography & radiology Flashcards
What is a radiograph?
An image produced by x-rays passing through an object and interacting with the photographic emulsion on a film
When were radiographs first used in dentistry?
1896
Where are electrons found?
orbiting round a nucleus in different energy shells (K,L,M etc)
What is the forbidden zone in terms of electrons?
Can move from shell to shell but cannot exist between shells
Shells contain maximum number of electrons, how much does each shell contain?
K = 2
L = 8
M = 18
N = 32
O = 50
What is energy required for in terms of electrons?
Energy is required to remove electron from atom and overcome binding energy which keeps it in it’s shell
What does the atomic number consist of?
Protons + neutrons
What is a radio-isotope
Isotopes with unstable nuclei which undergo radioactive disintegration
What is an anion?
Negatively charged atom or molecule if there are more electrons
What is an cation?
Positively charged atom or molecule if there are more protons
describe alpha particles?
- 2 protons + 2 neutrons (helium nucleus)
- large
- charge
- slow
- 1-2 mm in tissue
- 4-8MeV
- extensive ionisation
Describe beta particles
- electrons (fast electrons)
- small
- negative charge
- fast
- 1-2 cm in tissue
- 100keV-6MeV
- ionisation
When is ionisation a problem?
- When it occurs in living cells
- Can cause damage to tissues cataracts for example
- can cause damage to DNA directly or produce chemicals that do this damage - tumours or cancer
What happens when electricity flows through the coils of the elements?
- Electrons within the wire coils vibrate
- Current moves through the length of the coils
- Vibrating electrons produce heat
- Wire becomes red hot giving off light
- Radiant heat causes the movement of air molecules
- Surrounding area becomes hot
- Heat produced is proportional to current and voltage
