Principles and Practices of Radiation Protection Flashcards
(38 cards)
How should sealed sources be handled?
Time
Distance - tongs
Shielding - PPE (gloves)
Safe storage - secure and shielded
What are the routes through which a person may be exposed to radiation from an unsealed source?
- Injection (and needle stick injuries)
- Inhalation
- Ingestion
- Absorption (skin or wound)
- External irradiation
What are some practical radiation protection techniques?
Use PPE
Handle sources in designated areas
Monitor for contamination (areas and persons)
Use decontamination kits
Stop spread of contamination
Seal off areas to allow for decay
What considerations should be taken into account in deciding what to do about a radiation spillage?
Use of the room
Dose rate of the spillage
Amount of spillage
Type of source
Room designation
Control spread
What are the aims of radiation protection?
To reduce the risk of detrimental effects from radiation through
1. Preventing deterministic effects
2. Minimising the probability of stochastic effects
3. Ensuring any radiation exposure is justified
What is a deterministic effect?
An effect that can be related directly to the radiation dose received. There is a dose below which there is no effect. Once past this threshold the severity usually increases
What is a stochastic effect?
An effect that occurs on a random basis independent of the size of the dose. The effect has no threshold and is based on probabilities, with the chances of seeing the effect increasing with dose. If it occurs the severity of a stochastic effect is independent of the dose received
What is an example of a stochastic effect?
Cancer
What causes stochastic effects?
Radiation induced changes in the DNA and subsequent proliferation
What is the linear no threshold hypothesis?
Assumes all ionising radiation is dangerous (all ionising radiation can induce stochastic effects)
What are the 3 key principles of radiation protection?
- Justification
- Optimisation
- Limitation
What is justification?
Any exposure must be justified, in which benefits outweigh the risks (net benefit), including societal gain
What regulations specify the requirement for justification?
IR(ME)R17
What is JOPIIR?
Justification of Practices Involving Ionising Radiations Regulations 2018
- EU requirement that new practices involving IR are assessed to determine societal benefit against detriment
What common practices using IR are justified?
Radioisotope production
Radioactive tracers for medical techniques
Diagnosis
Treatment
Medical research
What is an example of a societal gain in the use of IR?
Breast screening programme
Well women screened (exposed to 0.4 mSv/scan) but saves ~ 1 in 200 women’s lives
What is optimisation?
Keeping the following ALARP:
- likelihood of incurring exposure
- number of people exposed
- magnitude of individual dose
taking economic and societal factor into account
Where do dose limits come from ?
UNSCEAR (UN) -> ICRP -> IAEA -> ED -> national legislation
What are planned exposures?
- Occupational
- Public
- Medical
- Medical legal
- Emergency (forseeable)
How are exposures limited?
PPE
Contingencies
Interlocks
Training
Design
Shielding
What is the hierarchy of control in terms of limiting exposure?
Elimination
Substitution
Engineering controls
Administrative controls
PPE
What is limitation
Designs to keep the risks of dealing with ionising radiation in the same order as other risks
True or False: Dose limits apply to patients
False - patients receive a justified benefit from the exposure
What are the four core ethical values of radiation protection?
- Beneficence/non-maleficence - promoting and doing good and avoiding harm
- Prudence - make careful, informed decision in the face of a lack of evidence and uncertainty
- Justice - fair distribution of advantages and burdens throughout population and environment
- Dignity - every person deserves respect, irrespective of circumstances or attributes
