T1: Radiation Protection

Question 1

Exsposure

Answer 1

The flow of Photons per unit of time through a point of interest in the air at a given distance from a radiation source
- describes amount of radiation present by measuring ionising effect on air
- in coluombs per kilogram

Question 2

What is kerma?

Answer 2

Interactions of photos release electrons possessing a range of energies
- Amount of kinetic energy transferred to electrons is called kerma

Kinetic Energy Released In Matter (gray)

Used to relate energy released in matter to energy absorbed in matter
- determine energy deposited in tissue, and extent of biological effect

Question 3

Definition of Absorbed does

Answer 3

Amount of radiation energy absorbed in medium, gray (Gy)
- equalling one joule per kilogram (energy absorbed per unit mass)

Question 4

Equivalent dose and Absorbed does realtionship

Answer 4

They are both numerically equal
- measured in sieverts

Question 5

Effective dose

Answer 5

The sum of the equivalent dose multiplied by the Tissue weighting factor
- measured in sieverts where the Radiation Weighting Factor and Tissue Weighting Factor are numerically equally

Question 6

Background Radiation
(External and Internal)

Answer 6

1. External radiation from cosmic rays of outer space, and natural radioactive substances in Earth’s crust
2. Internal radiation from radioactive elements in the air we breathe and in food

Question 7

Living Indoor

Answer 7

Radon arises naturally from radioactive decay of uranium and thorium
- rocks, soil, bricks, mortar, tiles and concrete

Question 8

Medical use

Answer 8

X-rays in radiography and radioactivity in nuclear medicine
- therapeutic radiation gives certain organs many times higher than the background dose

Question 9

Air travel

Answer 9

Flying can give you a dose around 100 micro siverts

Question 10

Background Radiation + Average Annual Radiation does in Australia

Answer 10

Higher Altitude = Less shielding affords from cosmic rays
Through drinks and food
Industries release radioactivity into environment
Smoke detectors
- Average Annual Radiation does in Australia = 2300 micro siverts

Question 11

Radiation Risk

Answer 11

Estimations of complicated radiation-induced cancer and genetic defects:
- do not differ from those occurring from other causes
- have a low incidence compared to the natural spontaneous incidence

The risk for developing cancer = 4.610-2 per Sv
The risk for hereditary effects is lower at 0.1x10-2

Average radiation worker = 2x10-4 per year

Question 12

What does ICPR stand for

Answer 12

International Commission on Radiological Protection

Question 13

ICRP principles of radiation protection

Answer 13

• practice is justified
• exposure be kept as low as reasonably achievable (ALARA) -> needs social and economic facotors
• dose and risk limits are not exceeded

Question 14

What are most common causes of exposure in work place

Answer 14

1. Careless work
2. Equipment failure
3. Inadequate training

Question 15

Risk assessment considerations

Answer 15

• Eliminate
• Substitute
• Isolate
• Engineering Controls
• PPE (Personal Protective Equipment)

Question 16

Does Limits for Effective dose in general, lens, skin, and “hands and feet”

Answer 16

Effective does:
Occupational Dose = 20 mSv av over 5 years, and in one tear the does cannot exceed 50mSv
Public Dose Limit = 1 msV (over 5 years)

The lens of the eyes:
Occupational Dose = 20 mSv
Public Dose Limit = 15 msV

The skin -> an average over 1cm2
Occupational Dose = 500 mSv
Public Dose Limit = 50 msV

The Hands and Feet:
Occupational Dose = 500 mSv
Public Dose Limit = -

Question 17

Pregnant Radiation workers

Answer 17

Have to limit dosage to 2mSv, and the foetus cannot recieve more than 1mSv