Intro and Safety

Question 1

Deterministic or non-stochastic effects are chronic. T/F

Answer 1

FALSE- this is an acute response

Question 2

What are deterministic or non-stochastic effects?

Answer 2

They occur when there is a threshold level of exposure, above which certain effects occur, and the severity is proportional to the dose. There is a “safe zone”.

Question 3

What are stochastic or probailistic effects?

Answer 3

These occur when there is NO threshold level, no “safe dose”. Every exposure increases the risks that disease, such as cancers, will occur.

Question 4

Stochastic or probailistic effects are a chronic/delayed thing. T/F

Answer 4

TRUE

Question 5

What 6 tissues are most sensitive to ionising radiation?

Answer 5

1. Organogenesis/rapid growth- so younger animals and foetuses (particularly 1st trimester) are more at risk than adults.
2. Cells that grow rapidly, such as skin (non-pigmented more at risk than pigmented) or GIT cells
3. Issues w/ high metabolic activity, such as the thyroid.
4. Bone marrow- damage results in decreases RBC, platelet and lymphocyte production
5. Gonads- damage results in decreased sex hormones and increased genetic mutations
6. Eye- ionising radiation can result in cataracts in the lens

Question 6

What effects can radiation have on the body?

Answer 6

• deposit energy in the body
• cause DNA damage
• create ionisation in the body- leading to free radicals
  These lead to biological damage, which is either stochastic/delayed or non-stochastic/acute effects.

Question 7

What is the absorbed dose of radiation?

Answer 7

The amount of energy “deposited” in a kg of a substance by the radiation

Question 8

What is the equivalent dose of radiation?

Answer 8

The absorbed dose weighted for harmful effects of different radiations (radiation wieghting factor wR)

Question 9

What is the effective dose of radiation?

Answer 9

Equivalent dose weighted for susceptibility to harm of different tissues (tissue weighting factor, wT). E.g. a wT for soft tissue will be different to that of a brain cell

Question 10

What does ALARA stand for?

Answer 10

As Low As Reasonably Achievable

Question 11

What are the 3 tenets of radiation safety?

Answer 11

1. TIME that a person is exposed to ionising radiation
2. DISTANCE between a person and a radioactive substance
3. SHIELDING used to protect a person

Question 12

WHat three questions should you ask yourself before making a radiograph?

Answer 12

1. Justification- each radiograph taken has to have a benefit for the animal that will outweigh the risk and cost of irradiation.
2. Optimisation- the operator must use the lowest exposure possible to obtain the radiograph
3. Compliance in limits- the operators must not exceed the max allowed exposure for the year.

Question 13

What is the inverse square law?

Answer 13

Double the distance from the source of radiation and you will reduce exposure dose by a factor of 4.
Distance is the most effective and easy means of protection!