Radiation Protection Flashcards
What is ionising radiation?
Ionising radiation (or ionising radiation) consists of subatomic particles or electromagnetic waves that have sufficient energy to ionise atoms or molecules by detaching electrons from them.
- In simple words ionising radiation is radiation that has enough energy to alter the structure of living cells and potentially cause health problems.
How do we quantify ionising radiation?
When we are interested on the effects of ionising radiation to living organisms, then the physical quantity of interest is the radiation Dose.
- Dose is measured in Gy (Grays).
- E.g. a patient who has a chest X-ray will receive a dose of 0.02 mGy.
What are the sources of ionising radiation?
Natural - 84%
Radon - 50%
Artificial - 16%
Medical - 15%
Internal - 9.5%
Gamma - 13%
Cosmic - 12%
Occupational - 0.2%
Fallout - 0.2%
Discharges - <0.1%
Products - <0.1%
Examples of Medical exposure
- X-rays and Radioactive isotopes used for imaging and treatment
Radioactive isotope - unstable nuclei which emits radiation whilst stabilising itself.
- Radiotherapy doses are higher but diagnostic contributes more to population as a whole
- Of the 15% of medical dose of entire population almost 90% is from diagnostic radiography
- CT = 7% of procedures
- CT = 47% of annual collective dose from diagnostic imaging
What is a radioactive isotope?
Unstable nuclei which emits radiation whilst stabilising itself.
What is required for a full radiation protection study?
- Radiobiology
- Genetics
- Statistical analysis of risk
- Methods of reducing radiation doses to workers
- Rate and decay patterns of radioactivity released into
the environment - Absorbing power of different materials to different
radiations
What are the 3 Golden Rules of Radiation Protection
- Less time spent near source = less radiation received.
- Greater distance from source = less radiation received.
- Behind shielding from source = less radiation received.
What damaging effects can ionising radiation have on the human body?
Ionising radiations are potentially damaging to the human body and can produce DETERMINISTIC (T) and STOCHASTIC (D) effects
What are deterministic effects and give examples
- Do not occur below a threshold dose
- Severity increases above threshold dose
- Therapeutic
E.g.
• Skin erythema (rash) at 3 Gy - small area
• Nausea/vomiting at 1 Gy - whole body
• Cataract at 5 Gy - eyes
What are Stochastic effects and give examples
- No threshold dose
- Risk of damage increases as dose increases
- At low doses biological effects are not predictable
- BUT there is always some risk
- Diagnostic
E.g.
• Cancer
• Inherited disease
What is inherited radiation damage?
- Does not introduce new, unique mutations
- May increase the incidence of the same mutations
that occur spontaneously - Radiation that damages the DNA of germ cells in the gonads causes gene mutations.
- These mutations increase with DOSE.
- Damage to gonads causes mutations in offspring.
Stochastic vs Deterministic effects
- Probability of effects occurring increases with dose.
- Severity is 100% for stochastic, if cancers gonna occur it will happen.
- Deterministic effects are threshold health effects, that are related directly to the absorbed radiation dose and the severity of the effect increases as the dose increases.
- Stochastic effects occur by chance, generally occurring without a threshold level of dose.
What are the aims of radiation protection?
- To prevent deterministic effects by keeping doses below the thresholds for those effects
- To reduce the risk of stochastic effects to levels which are considered acceptable
What is the ICRP?
The International Commission on Radiological Protection.
- Non-government body - expert advisers (200 volunteer scientists)
- They make recommendations either broad or detailed based on research
- These are not mandatory but influential
- Differences between countries are found in methods of enforcement
Identify the ICRP
- ICRP 121 - Radiological Protection in Paediatric Diagnostic and Interventional Radiology (2013)
- ICRP 120 - Radiological Protection in Cardiology (2013)
- ICRP 117 - Radiological Protection in Fluoroscopically Guided
Procedures outside the Imaging Department (2010) - ICRP 113 - Education and Training in Radiological Protection for
Diagnostic and Interventional Procedures (2009) - ICPR 105 - Radiological Protection in Medicine (2007)
- ICRP 103 - The 2007 Recommendations of the International
Commission on Radiological Protection (2007)
State the differences in regulations and the UK legislation
New Regulations
- The Euratom/European Union Directive Basic Safety Standards Directive 2013 (BSSD) stipulated that all EU member states must have new radiation safety regulations in place by 6 February 2018
UK legislation
- Ionising Radiations Regulations 2017 (enforced by HSE, Health and Safety Executive)
- Ionising Radiations (Medical Exposures) Regulations 2017 (enforced by the CQC, Care Quality Commission)
State the Principles of Radiation Protection
- Justification – The benefits of the use of radiation must outweigh the associated risks and hazards
- Optimisation – ALARP (As Low As Reasonably Practicable)
- Dose Limitation – staff and general public (not patients)
What is the IRR 2017?
Ionising Radiations Regulations 2017
These cover the use of ionising radiations in the workplace:
- Hospitals
- Dental surgeries
- Power stations
- Industrial radiography
- Research
What does the IRR 2017 state and protect?
- The employer must provide a safe working environment for staff and public.
- The employees must maintain this safe environment for the people who enter into it :
- Themselves
- Patients
- Others
What is meant by the Dose Limitation?
• Dose limits are set for radiation workers and members of the general public
• 20 milliSieverts per year for radiation workers (if 6 is reached - investigate)
• 1 milliSievert per year for the public
What does IRR 2017 state for radiographers?
- Must arrange for personal dosimetry for employees who could receive more than 3/10 of the annual dose limit
- 6mSv/year
What areas are included in IRR 2017?
Controlled Areas
• Any area where radiation doses could exceed 6mSv a year
• Entry into this area must be restricted
• Physical demarcation of controlled area
Supervised Areas
• Any area not designated as a controlled area but under review
• Likely to receive 1mSv a year