IRMER Radiation Protection

Question 1

What are the 3 guidelines need to be aware of?

Answer 1

IRR17 - Ionising radiation regulations
IRMER17 -
FGDP 2020 - Guidance notes for dental practitioners on safe use of x-ray equipment

Question 2

How long will this training cover you for?

Answer 2

5 years

Question 3

What is radiation?

Answer 3

Radiation with energy to remove electrons from an atom causing it to become charged/ionised

Question 4

What are the 4 different types of radiation?

Answer 4

X rays
Gamma rays
Alpha rays
Beta rays

Question 5

What is the source of x rays?

Answer 5

Energetic electrons

Question 6

What are x rays used for?

Answer 6

Diagnostic imaging, radiotherapy

Question 7

Which rays are sourced for radioactive material

Answer 7

Gamma rays
Alpha rays
Beta rays

Question 8

What are alpha rays used for?

Answer 8

No use in dentistry

Question 9

Which rays are used for isotope imaging and therapy?

Answer 9

Gamma rays
Beta rays

Question 10

Which rays are particles? Which rays are electro-magnetic?

Answer 10

Particles - alpha and beta rays
Electro-magnetic - x and gamma rays

Question 11

Describe structure of x ray tube

Answer 11

Glass tube, vacuum inside, cathode (where e- come from) and an anode, tube is surrounded by oil (inefficient process) then a lead casing (for protection)

Question 12

How is the x ray produced?

Answer 12

When high energy electron beam hits target (cathode –> anode)

Question 13

What are the 2 types of x rays?

Answer 13

Characteristic radiation
General radiation (Bremsstrahlung)

Question 14

How is Bremsstrahlung radiation produced? (4)

Answer 14

E- decelerate when they pass +ve nucleus
E- loses energy
Energy emitted in form of radiation
99% converted to heat, 1% converted to x rays

Question 15

How is characteristic radiation produced?

Answer 15

Incoming e- ejects an inner e- of orbit
Higher energy e- takes its place
Releases x ray
This energy is a characteristic of the target material

Question 16

What does level of characteristic radiation depends on?

Answer 16

Which energy level e- passed from and into

Question 17

Why is there a spectrum of energies for Bremsstrahlung radiation?

Answer 17

Depends on how much the incoming e- has been decelerated

Question 18

What is the average UK radiation dose?

Answer 18

2.7 mSv (AKA background radiation)

Question 19

What are the sources of radiation? (6)

Answer 19

48% radioactive radon gas from ground
16% medical radiation
13% terrestrial (building material) / gamma radiation
12% cosmic radiation (sun)
11% intakes from food
0.2% from nuclear weapon fall out

Question 20

Which foods are naturally radioactive?

Answer 20

Brazil nuts
Lima beans
Bananas
Carrots
Potatoes
Red meat
Beer
Water
Peanut butter

Question 21

Why is radiation a problem to tissues?

Answer 21

Causes break in DNA strand
Normally this can repair
If doesn’t repair - leads to cell death
If repairs incorrectly - leads to cell mutation

Question 22

What is a long term problem with radiation exposure?

Answer 22

Biological effects may not be visible for weeks / months / years

Question 23

Which molecules are responsible for attacking DNA? What process?

Answer 23

Free radicals - oxidation

Question 24

What can protect cells against free radicals?

Answer 24

Antioxidants
E.g. red wine / blueberries

Question 25

What is the photoelectric effect? How does this effect images?

Answer 25

Photons falling knock electrons out of a surface Photoelectric absorption causes contrast in images

Question 26

What is Compton scattering?

Answer 26

X ray encounters an e- from outer shell with little binding energy E- is ejected and energy is re-emitted in form of x ray Results in x ray with different direction and less energy This x ray not used for image production

Question 27

What are the 3 units need to know for x rays

Answer 27

Absorbed dose Equivalent dose Effective dose

Question 28

What is absorbed dose? Measurement? Unit?

Answer 28

Energy deposited per unit mass of material Measured in J kg-1 Unit gray (Gy)

Question 29

What is equivalent dose? Measurement? Unit?

Answer 29

Absorbed dose multiplied by radiation weighting factor (Wr) Represented by H (H = S Dr Wr) Measured in J kg-1 Unit Sievert (Sv)

Question 30

What is the weighting factor of electrons?

Answer 30

1

Question 31

What is the weighting factor of photons, protons, alpha, heavy nuclei?

Answer 31

Photons = 1 Protons = 5 Alpha = 20 Heavy nuclei = 20

Question 32

What does equivalent dose not take into account?

Answer 32

The tissue being radiated

Question 33

What is the effective dose?

Answer 33

Equivalent dose multiplied by the weight factor of the tissue (Wt) E = S Ht Wt Measured in Sieverts (Sv)

Question 34

What is tissue weighting factor of the entire body?

Answer 34

1

Question 35

What is the tissue weighting factor of bone and salivary glands?

Answer 35

0.01 bone 0.01 SGs

Question 36

What are the effects of radiation?

Answer 36

Somatic Genetic Deterministic Stochastic

Question 37

What are somatic effects?

Answer 37

Manifested in person irradiated

Question 38

What are genetic effects?

Answer 38

Manifested in offspring of person irradiated

Question 39

What are deterministic effects? AKA? Determined by? What does severity depend on? Examples of effects?

Answer 39

AKA Certain, tissue reaction effects Effects will occur if a certain threshold is passed Severity depends on dose of radiation Erythema, sterility, radiation sickness / burns, epilation, cataracts, death

Question 40

What are stochastic effects? AKA? Determined by? What does severity depend on? Example of effects?

Answer 40

AKA Random radiation effects Determined by total dose of radiation received Severity is independent of dose Cancer, genetic effects

Question 41

What is not considered a potential risk with dental x rays?

Answer 41

Genetic defects

Question 42

What is effective dose of IO radiographs?

Answer 42

0.3 - 21.6 mSv

Question 43

What is effective dose of panoramic radiographs

Answer 43

2.7 - 38 mSv

Question 44

What is the background radiation equivalent of a periapical?

Answer 44

3.5 days exposure

Question 45

What is the background radiation equivalent of a panoramic?

Answer 45

6 days