16. RADIATION HEALTH EFFECTS: SAFETY

Question 1

1. When was the most recent set of the fundamental ICRP Recommendations published?

Answer 1

• this was ICRP Publication 103
• it is called the: “The 2007 Recommendations of the
  International Commission on Radiological Protection”

Question 2

2. What does “The 2007 Recommendations of the International Commission on Radiological Protection” outline?

Answer 2

• it describes the entire system of Radiological
  Protection
• it forms the basis for all the relevant EU and
  International Legislations

Question 3

3. What does the scope of Radiological Protection include?

Answer 3

• it includes all the exposures to ionising radiation
• these exposures can come from any source
• regardless of the exposure size or origin

THIS INCLUDES:
- Natural Sources of Radiation
- Man made sources of Radiation

Question 4

4. When does the system of protection against radiation apply itself fully?

Answer 4

• when the source of exposure can be controlled
• when the pathways leading to the exposure can be
  controlled
• a set of fundamental principles will be applied in all
  circumstances
• this does not mean that there is equal protection
  treatment in all the circumstances

Question 5

5. What is a Graded Burden of Obligation?

Answer 5

• this is something that is expected
• it is brought about through regulatory controls and
  procedural arrangements
• it depends on the level of risk
• it depends on the Flexibility of control

Question 6

6. Which two concepts help to precisely describe the domain of radiological protection control?

Answer 6

1. Exclusion
2. Exemption

Question 7

7. Why can certain situations be excluded?

Answer 7

1. CONTROL IS NOT POSSIBLE
   - EG: potassium 40 occurring naturally in the human
   body
2. CONTROL IS OBVIOUSLY IMPRACTICAL
   - EG: exposure to cosmic radiation

NB:
- control in these situations is unjustified
- the exempts these situations from regulatory
requirements

Question 8

8. What kind of situations can expereince exemption from regulatory requirements?

Answer 8

• situations in which the effort to control is excessive
  compared to the associated risk

Question 9

9. What do National Regulators do?

Answer 9

• they decide what is excluded
• they decide in which circumstances control is
  unwarranted

Question 10

10. What is the Primary Aim of the system of radiological protection according to ICRP
    Report 103?

Answer 10

Question 11

11. What are the Human Health Objectives of the system of Radiological Protection according to the ICRP Report 103?

Answer 11

Question 12

12. How are Deterministic Efforts preventable?

Answer 12

• by keeping the doses below a specific threshold

Question 13

13. How are Stochastic Effects managed?

Answer 13

WITH STOCHASTIC EFFECTS:
- even a small dose might give rise to a risk of a
condition

THE PROTECTION SYSTEM AIMS TO:
- prevent harm that is preventable
- manage harm that cannot be prevented

Question 14

14. List 2 characteristics of Deterministic Effects?

Answer 14

1. They depend on the doses
2. There is a threshold limit
   • any dose below this limit with have no effect

Question 15

15. List 4 characteristics of Stochastic Effects?

Answer 15

1. They are probabilistic
2. They have no threshold
3. The severity of the effects is not related to the dose
4. There is a risk of developing conditions due to
   Stochastic effects whenever we are exposed to
   radiation
   - EG: cancer

Question 16

16. What is the system of Radiological Protection based on?

Answer 16

1. Scientific Knowledge
   - EG: the Photoelectric Effect
   - EG: the Compton Effect
   - EG: Pair Production
2. Ethical Values
3. Experience

Question 17

17. What can science give us information to, with regards to Radiological Protection?

Answer 17

1. HOW RADIOACTIVE METALS MOVE
   
   • through the environment
   • how they move through human bodies once they
     have been inhaled or ingested
2. HOW RADIATION INTERACTS WITH MATTER
3. THE EFFECTS OF RADIATION ON HUMAN HEALTH
   
   • and on the environment

NB:
- all these aspects are important for Radiological Protection

Question 18

18. Why are Ethical Value Judgements necessary in Radiological Protection?

Answer 18

• they help to decide what may be tolerable or
  intolerable

THESE ETHICAL VALUE PRINCIPLES INCLUDE:
- Precaution
- Wisdom
- Justice
- Beneficence (the need to do good)

Question 19

19. How does ICRP Publication 103 define Stochastic Effects?

Answer 19

STOCHASTIC EFFECTS INCLUDE:
- cancer
- heritable effects
(these are the effects
that will appear in
future generations)

Question 20

20. What kind of model does the System of Radiological Protection use?

Answer 20

• it uses the Linear No-Threshold (LNT) Model
• it uses this as a basis
• this model is scientifically plausible
• it is not universally accepted as the biological truth

THIS MODEL IS PRUDENT FOR PUBLIC POLICY:
- these policies are aimed at avoiding unnecessary risks
from any kinds of exposures and ionising radiation
- this risk is an estimation

Question 21

21. What does the Linear No-Threshold (LNT) Model assume?

Answer 21

• it assumes that any dose will produce a proportionate
  increment in probability
• this happens no matter how small the dose is

THE PROBABILITY:
- is one that concerns itself with the chance of cancer or
heritable effects incurring

Question 22

22. How are Deterministic Effects described by ICRP Publication 118?

Answer 22

THE THRESHOLD:
- is the key parameter
in terms of radiological
protection

Question 23

23. What did ICRP Publication 118 focus on when it came to Deterministic effects?

Answer 23

• they focused on estimating the dose thresholds
• this was defined as the dose resulting in 1% of
  individuals
• these individuals were exhibiting a specified effect

Question 24

24. What does defining a threshold NOT IMPLY?

Answer 24

• it does not imply that there will be no biological effects
  that occur at lower doses
• it defines the dose above which specified effects
  become clinically apparent in a small percentage of
  individuals

Question 25

25. What is a Central feature of Radiological Protection?

Answer 25

- calculating the dose of the radiation received

Question 26

26. What are the 3 dose quantities that are used?

Answer 26

1. THE ABSORBED DOSE - this is measured in Grays (Gy) - it is the dose absorbed by the body 2. THE EQUIVALENT DOSE - this is measured in Sievert (St) - it is the Absorbed dose x the radiation weighting factor - it takes into consideration the relative biological effectiveness (RBE) of various radiation types 3. THE EFFECTIVE DOSE - this is measured in Sievert (Sv) - it is the Equivalent dose x the tissue weighting factor - it looks at the sensitivity of the tissue to radiation exposure

Question 27

27. What can be said about the averaged absorbed dose when it comes to Radiological Protection Applications?

Answer 27

- the absorbed dose is averaged over tissue volumes - different organs and tissues have different sensitivities to radiation

Question 28

28. What can be said about the Absorbed Dose at low doses?

Answer 28

- the absorbed dose averaged over a specific organ or tissue is linked with the radiation detriment for Stochastic Effects - this has a sufficient accuracy for protection purposes

Question 29

29. What can be said about different ionising levels?

Answer 29

- they have different levels of effectiveness in causing biological effects EXAMPLES OF IONISING RADIATION LEVELS: - Alpha - Beta - Gamma - Neutron - other varieties of charged particles

Question 30

30. What would happen if all Radiation Effects were deterministic in nature?

Answer 30

- the system of radiological protection could be quite straightforward - we would be able to simply avoid exposures that exceed the thresholds as they are potentially dangerous - exposures below the thresholds would be considered safe

Question 31

31. What does the Probabilistic nature of Stochastic effects mean?

Answer 31

- it means that there is no clear distinction between the levels of exposure - we cannot identify which levels are safe and which are dangerous

Question 32

32. What is the appropriate level of protection from radiation based on?

Answer 32

- it is based on what is deemed acceptable in a given circumstance - ethical considerations play a role here - such as justice and beneficence

Question 33

33. What are the 3 Fundamental Principles of the ICPR System of Protection?

Answer 33

1. Justification 2. Optimisation 3. Dose Limitations

Question 34

34. What is the Principle of Justification?

Answer 34

- this means that the benefits should outweigh the detriments for the patient when we introduce a new source of radiation - this also applies when we remove a risk of potential exposure from an existing one - this principle applies under all circumstances - this principle is the responsibility of the radiologists and the referring doctors

Question 35

35. What is the Principle of Optimisation?

Answer 35

- it demands that the net benefit to society and individuals should be maximised - there should be a balance between the image quality and the patient radiation dose - this concept defines the best level of protection under the prevailing circumstances