Principles and Practices of Radiation Protection Flashcards
(49 cards)
How are the risks of detrimental effects from ionising radiation reduced?
1) Deterministic events are prevented
2) The probability of stochastic effests is minimised
3) 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 typically 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. Cancer is a stochastic effect.
What is the current model for stochastic effects?
The linear no threshold model (LNT)
What is the linear no threshold model?
A hypothesis that assumes all ionising radaition is dangerous and can induce stochastic effects.
What does it mean to justify a radiation exposure?
An exposure is only justified if there is a sufficient positive net benefit
What does it mean to optimise a radiation exposure?
All justified exposures must be kept as low as reasonably practicable (ALARP)
How are limitations put on radiation exposures?
They are set well below any threshold levels
What are the ICRP’s 3 key principles of radiation protection?
- Justification
- Optimisation
- Limitation
What are the Justification of Practices Involving Ionising Radiation Regulations (2018)?
A requirement under EU law that new practices involving ionising radiation are assessed to determine societal benefit against detriment
Give 5 examples of justified medical practices
- Production of radioisotopes
- Use of radioactive tracers
- Diagnosis
- Treatment
- Medical and biomedical research
Why are screening programmes involving ionising radiation justified?
Because they provide societal benefit as well as potential individual gain.
Optimising dose considers both ________ and ________ factors.
Economic
Societal
What is the difference between ALARA and ALARP
As Low As Reasonably Achievable
As Low As Reasonably Practicable
Just because something is achievable doesn’t mean that it is practicable
Where do dose limits come from?
They are originally assessed on a global level by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). This assessment informs ICRP recommendations which are implemented on a national level.
What is the difference between planned and emergency exposures?
Planned exposures are deliberate and controlled exposures to ionising radiation, meaning they are thoughroughly optimised and justified.
Emergency exposures aren’t planned, but they are foreseeable, meaning that they can still be optimised and limited.
Give 4 examples of planned exposures
- Occupational exposures
- Public exposures
- Medical exposures
- Medical legal exposures
What steps can be taken to reduce the likelihood and consequences of emergency exposures?
- Manufacturer designs (shielding and collimation)
- Having machine interlocks
- Contingency plans
- Providing PPE
- Raising awareness of risk
- Training
- Clear instructions
What are the 5 stages in the hierarchy of control measures?
Do dose limits apply to patients? Why?
No because they receive a justified benefit from the exposure
What are the 4 core ethical values of radiation protection?
1) Benefice/non-malificence (promoting good and avoiding harm)
2) Prudence (making carefully informed decisions)
3) Justice (fair distribution of advantages/burdens)
4) Dignity (respecting all patients)
What are the 6 key sources of background radiation dose in the UK?
- Radon gas
- Medical
- Internal
- Terrestrial
- Cosmic
- Consumer products
What is the average background dose per year in the UK?
2-3 mSv/year
What % of background radiation dose is from radon gas?
54%
