Ionising Radiation

Question 1

Source of exposure

Answer 1

External - uniform irradiation of the whole body - SEALED
Internal - inhaled or absorbed, UNSEALED
Largest source is natural background radiation

Question 2

Type of ionising radiation

Answer 2

Alpha particles - (+) charged, cannot pass piece of paper or intact skin, little energy, can cause tissue damage at short range
Beta particles - electrons (-ve) charge, can pass through skin. Stopped by glass or thin layers of metal
Neutrons - uncharged with intermediate mass and variable energy
Gamma and x-rays - cause less damage to tissue

Question 3

Bq

Answer 3

Becquerel
Rate of transformation of radioactive material
Unit of decay

Question 4

Equivalent Dose

Answer 4

Different types of radiation produce different degree of biological damage. Therefore multiplied by Q.
Equivalent Dose (Sv) = absorbed dose (Gy) x Q

Question 5

Q

Answer 5

Weighting factor
beta/gamma/xrays - 1
Alpha - 20
neurtons - 10

Question 6

Absorbed Dose

Answer 6

Measure of energy deposition per unit of mass

1Gy = 1j/kg of energy deposition

Question 7

Effective Dose

Answer 7

Risk to various tissues varies from one tissue to another

Weighting factor used for each tissue.

Question 8

Somatic Effects

Answer 8

Damage to tissue sustained by an irradiated individual
Can be acute or delayed.
Can be passed on as a hereditary effect

Question 9

Stochastic Effects

Answer 9

Risk increases progressively with dose received but there is no detectable threshold (eg induction of carcinogenesis)
Risk of of cancer in radiation workers is 4% per Sv

Question 10

Deterministic

Answer 10

Severity of the effect increases progressively with dose and will not occur until a certain threshold of dose has been received (eg radiation burn)
(non-stochastic)

Question 11

ICRP

Answer 11

International Commission on Radiation Protection

Aim to prevent non-stochastic effects and limiting stochastic effects

Question 12

Dosemeters

Answer 12

Thermoluminescent dosometers (TLDs)
Can measure over a wide range for both whole body and finger monitoring
Not as sensitive to heat and humidity as film badges
More sensitive to low doses than film badges

Question 13

Film Badges

Answer 13

Film badges can record radiation that is permanent

Not widely used as expensive compared to TLDs

Question 14

Unsealed radiation measuring

Answer 14

Surface contamination
Airborne sampling
Biological monitoring

Question 15

Control of external radiation exposure - 3 Factors

Answer 15

Time
Distance
Shielding

Question 16

Classification of Areas

Answer 16

Supervised - dose rate less than 7.5Sv/h but may receive effective dose of greater than 1mSv a year
Controlled - dose rate can exceed 7.5Sv/h and workers may receive effective dose of at least 6mSm a year

Question 17

Gray (GY)

Answer 17

Absorbed dose

Question 18

Sievert (Sv)

Answer 18

Equivalent dose = Gy x Q

Question 19

What stops different radiation

Answer 19

Alpha - skin, paper
Beta - glass, aluminuim
Gamma/x-rays - attenuated by lead
Neutrons - concrete

Question 20

Cells most affected by radiation

Answer 20

Lymphocytes

Question 21

Approved Person

Answer 21

For Diving regulations

Question 22

Appointed Person

Answer 22

For all others like asbestos, lead and radiation.

Question 23

Optical Radiation

Answer 23

Control of Artificial Optical Radiation at Work Regulations

Protect workers from risks of light sources, UV light/lasers/infrared.