Topic 8: radiation saftey Flashcards
1
Q
What is the ICRP?
A
- Set of fundamental recommendations
- Describes system of radiological protection + basis of EU + international legislations
- Scope of protection includes = all exposures to ionizing radiation no matter size + origin = natural/man-made
2
Q
What are the aims of ICRP?
A
- Contribute appropriate protection for people + environment against effects of exposure without limiting human actions
- Manage + control exposure = deterministic effects are presented + stochastic are reduced to reasonable achievable
3
Q
When is the system applied?
A
- Only fully applied = source of exposure/ pathway can be controlled
- Fundamental protection principles applied = all circumstances
- Broad scope doesn’t mean equal treatment + protection in all circumstances
4
Q
2 concepts that determine where/how radiation protection rules should be applied
A
1) Exclusion
2) Exemption
5
Q
When can situations be excluded?
A
- Control not possible = potassium 40 naturally occuring in body
- Control impractical = cosmic radiation
6
Q
When can situations be exempted?
A
- Control regarded as unjustified
- Effort to control = exessive compared to risk
- Up to national regulators to decide under circumstances
7
Q
How are effects prevented
A
- Deterministic = prevent by keeping dose below threshold
- Stochastic = small dose can give risk = system aims to manage what cannot be prevented
8
Q
What is the system of radiological protection based on?
A
- Scientific knowledge
- Experience
- Ethical values
9
Q
What information does science give us?
A
- How radioactive material moves through environment/body
- Radiation interacts with matter
- Effect of radiation
10
Q
What are the radiological principles?
A
- Precaution
- Wisdom
- Justice
- Beneficence
11
Q
Define stochastic effects according to ICRP
A
- Malignant disease + heritable effets = probibility if effect occuring NOT severity = function of dose without threshold
12
Q
Describe the linear no-threshold model
A
- Assumes any does = produce proportionate probability of cancer/heritable effect
- Scientifically plausible model
- NOT universally accepted
- Considered important for public policy aiming to avoid unnecessary risk of exposure
13
Q
Define deterministic effect according to ICRP
A
- Injury in populations cells by threshold dose + increase in severity as dose increases = tissue reaction
14
Q
What are the protection applications for AD?
A
- Averaged over tissue volume
- At low dose AD averaged over specific organ = radiation detriment for stochastic effect
- Different radiations = differing levels of effectiveness to cause effect
15
Q
What are the protection applications for equivalent dose?
A
- Based on AD + takes into account biological effectiveness of radiation
- Different tissues have different sensitivities
16
Q
What are the protection applications for effective dose?
A
- Takes into account different sensitivities of tissues
17
Q
3 fundamental principles of ICRP system
A
1) Justification
2) Optimization
3) Dose limitation
18
Q
Describe justification
A
- Any decision that alters radiation exposure = do more good than harm
- Benefits > risks
- Under all circumstances
19
Q
Describe optimization
A
- Likelihood of suffering exposure + number of people exposed + magnitude of doses = all kept low as possible taking into account economical + societal factors
- Net benefit to society + individuals maximized
- Under all circumstances
- Soft restrictions = dose/risk constraints
- Hard restrictions = dose limits
20
Q
Define ALARA principle
A
- As Low As Reasonably Achievable = help limit dose of exposure
21
Q
Describe dose limitation
A
- Total dose from regulated source in planned exposure other than medical = shouldn’t exceed limit recommended by commission
- Hard restriction
- Penalties = if cause individual to exceed
- Don’t apply under all circumstances
22
Q
3 principles to reduce exposure
A
1) Time
2) Distance
3) Shielding
23
Q
What is the effective dose for occupational/public?
A
- Occupational = 20 mSv per year
- Public = 1 mSv per year
24
Q
What is the annual equivalent dose in eye lens for occupational/public?
A
- Occupational = 20
- Public = 15
25
What is the annual equivalent dose in skin for occupational/public?
- Occupational = 500
- Public = 50
26
What is the annual equivalent dose in hands/feet for occupational/public?
- Occupational = 500
- Public = n/a
27
How is exposure organized?
1) Exposure situation:
- Planned
- Existing
- Emergency
2) Category of exposure
- Occupational
- Medical
- Public
28
Describe exposure situations
- Planned = protection can be planned in advance + exposure predicted
- Existing = situations may cause high enough exposure for protective action e.g. radon + naturally occurring
- Emergency = unexpected = urgent protective action or long term
29
Describe categories of exposure
- Occupational = workers as a result of job = in any exposure situation
- Medical = diagnostic/interventional/therapy = planned exposure situation even emergency
- Public = all other existing exposures = in any exposure situation
30
Describe the purpose of diagnostic reference levels
- Help optimization of patient protection
- Accomplished = avoid radiation not contributing to clinical purpose
- Used = improve distribution of observed results for general medical imaging = reducing unjustified high/low values
- Promote narrower range of values = good practice for imaging tasks
- Promote optimum range for specified imaging protocol
- Selection of vales made by professional body + national health + radiological protection
- Values based on relevant regional + national + local data
