1. What is an x-ray?

Question 1

LOs

Answer 1

• Describe the nature and properties of X-ray
• Appreciate why they are described as ionising radiation
• Explain the electromagnetic spectrum
• Classify and understand the dangers associated with ionising radiation

Question 2

what is an x-ray?

Answer 2

• high energy (wave packet) of energy called ‘photon’
• able to penetrate human tissues

Question 3

Features of x-rays?

Answer 3

• millions of photons make x-ray beam
• some have high energy + pass through patient
• some have little energy + stop inside patient
• travel in straight lines - no bend
• require no medium, can pass through vacuum
• originate + interact @ atomic level
• blacken film emulsion to create visual radiographic image
• Each photon = bullet
• Different machines produce different photons
• Millions of photons make a X-ray beam
  + photons are not all the same
  + difference in energy
• Ionising radiation - photon energy high and short wavelength
• can damage human tissue

Question 4

what are x-ray photons

where do they originate from?

Answer 4

• form of high energy electromagnetic radiation
• forms part of EM spectrum
• inside x-rays, from tungsten target

Question 5

type of radiation x-rays and gamma rays are?

Answer 5

• ionising radiation
• consist of photons of energy

Question 6

Where do X-rays come from?

Answer 6

Man made

Come from machines

Controlled by a control panel

Question 7

Where do gamma rays come from?

Answer 7

Naturally occurring

Emitted by radioisotopes

Responsible for background radiation
- emitted from rocks + soil in earths crust
- outer space
- certain foods

Question 8

gamma rays?

Answer 8

One of the radioactive emissions ( alpha particles , beta -ve and +ve , gamma rays )

Ionising

Question 9

What happens when X-ray photons hit patient?

Answer 9

1. pure scatter
   - no energy loss
2. scatter + absorption
   - some loss of energy
3. transmitted unchanged
4. absorbed
   - photon disappears

• Highest energy photons pass through patient unchanged
• Lowest energy photons absorbed

Question 10

what are the damaging effects of x-rays on human tissue?

how classified?

Answer 10

1. SOMATIC DETERMINISTIC/ CERTAINTY EFFECTS
   a) acute
   b) chronic
2. SOMATIC STOCHASTIC EFFECTS
3. GENETIC STOCHASTIC EFFECTS

Question 11

SOMATIC DETERMINISTIC (CERTAINTY) EFFECTS

1. what?
2. acute vs chronic effects
3. severity of effects
4. does it occur in dentistry

Answer 11

1.
somatic = person being irradiated
deterministic = will deffo happen

2.
acute = short term
- radiation sickness
- coma
- death

chronic = long term
- hair loss
- damage to blood vessels
- cataract form (eye)

3. proportional to amount of rad received
4. • threshold dose = below which they do not occur
     - in dent = below threshold dose

Question 12

SOMATIC STOCHASTIC EFFECTS

1. what
2. severity threshold
3. related to dent

Answer 12

1.
somatic = refers to body of person being irradiated

stochastic - by chance, governed by probability
EG. cancer induction

2.
- No known threshold , can develop with any amount of radiation

• Any exposure puts patients at risk
• Size of exposure doesn’t affect severity , only increases probability

3.
- in dent use small amounts of radiation + little films
- BUT small dental exposure can induce malignant change = cancer = dangerous
- cancer is same as if large exposure

Question 13

GENETIC STOCHASTIC EFFECTS

1. what
2. amount of rad needed to occur
3. relation to dent

Answer 13

1. • Involves future offspring of person irradiated
   • Chance effects , governed by probability
2. • any amount
   • BUT reproductive organs need to be irradiated for damage to genetic material to occur
3. • V unlikely as x-ray beam aimed at teeth + jaws

Question 14

Aims of radiation protection

Answer 14

Prevent deterministic effects
- rules + guidelines based on scientific evidence

Limit probability of stochastic effects
- acceptable level of risk
- weighed against potential benefit