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
State management of Radiation Protection IRR 2017
- Appointment of a Radiation Protection Adviser (RPA)
- This will be a radiation expert and usually a physicist
- Available for advice and assistance when dealing with radiation protection issues
State the Information, Instruction and Training of IRR 2017
- All employees must have received appropriate training
- Employees must know:
- Risks to health
- Precautions to be taken
- Importance of complying with regulations
What are the Local Rules of IRR 2017?
- Written statements which inform employees of controlled & supervised areas, risks associated with procedures, levels of access
- Must be displayed
- All staff to read and sign
- Names of RPS (radiation protection supervisor) and RPA (radiation protection advisor) must be included
State the Radiation Protection supervisors’ guidelines and role
Employer must appoint one or more RPS’s
- Role is to ensure that on a day to day basis the requirements for radiation protection are fulfilled
- Must be senior and have good knowledge of subject
- Link with RPA and management
What is the designation of Classified persons?
- Designated as a classified worker if you receive in excess of 6mSv per year.
- An employee will not be classified unless they are 18 or over & undergone health assessment.
State the Ionising radiation regulations 2017
- Dose limits – 20 mSv/yr workers & 1 mSv/yr public
- Personal dosimetry
- Controlled areas identified – > 3/10 dose limit (must be restricted)
- Radiation Protection Supervisor appointed - usually a senior radiographer
- Radiation Protection advisor – Medical physics expert (MPE)
- Local rules – read and signed by all employees
What is the IR(ME)R 2017?
- Came into force in 6 Feb 2018
- To protect the patient
- Covers duties of employers and employees in ensuring
that x-ray equipment, shielding and standard operating procedures meet adequate standards of radiation protection - Care Quality Commission oversees compliance
What medical exposures does IR(ME)R regulations apply to?
• In medical diagnosis or treatment
• As part of occupational health surveillance
• As part of health screening programmes
• In medical or biomedical, diagnostic or therapeutic research programmes
• As part of medico-legal procedures
What are Carers and comforters and what must you consider?
Individuals who are knowingly and willingly exposed to ionising radiation through support and comfort of those undergoing exposure
Consider:
- Dose constraint
- Dose optimisation
- Recording / reviewing
Name the Specified Duty holders.
- Employer
- Referrer
- Practitioner
- Operator
State what an employer is.
Any natural or legal person, in the course of trade, business or other undertaking, carries out (other than an employee), or engages others to carry out medical exposures at a given radiological installation.
In NHS the hospital trust is the employer.
What are the duties of an employer?
- Written procedures for medical exposures (6)
- Written protocols for every type of standard radiological
practice for each equipment (6) - Referral criteria for medical exposure (6)
- QA programmes (6)
- Clinical audit (7)
- Ensures adequate training of staff
- Ensures adverse incidents involving radiation other than defective equipment are investigated - accidental or unintended exposure
- Review why reference dose levels are exceeded and take action (e.g. individual training)
What are written procedures?
- Advice obtained from other colleagues in radiology, radiotherapy and NM etc.
- Practitioner may write them but employer is still responsible
E.g.
- Positive ID procedure
- Procedure for enquiries of females of child bearing age
- Procedures for giving information and written instructions
- Specific to each machine, room and examination
What is a referrer?
A registered medical or dental practitioner, or other health professional who is entitled in accordance with the employer’s procedures to refer individuals for medical exposure to a practitioner.
- Agreement at local level between employer and health care professional
- e.g. certain health care professionals may refer patients for extremities but not CT
- Screening programmes exclude referrer
What is a practitioner?
A registered medical or dental practitioner, or other health professional who is entitled in accordance with the employer’s procedures to take responsibility for an individual medical exposure.
- Agreed locally between employer and health care professionals
- e.g. can act as practitioner for extremities, but not interventional procedures
- Requires full knowledge of potential benefit and therefore adequately trained
What is an operator?
Any person who is entitled in accordance with the employer’s procedures to carry out any practical aspect associated with the procedure of a medical exposure.
Who is an operator and state responsibilities.
- Responsibilities must be clearly defined in written procedures
- e.g. by profession, grade, or individual name (Job descriptions)
- Operators include doctors, medical physicists, medical physics technicians, nurses, radiographers, radiopharmacists and assistant practitioners
Physicists employed by Trust check equipment prior to use
What is the practical aspect?
The physical conduct of any of the exposure and any supporting aspects including handling and use of radiological equipment, and the assessment of technical and physical parameters including radiation doses, calibration and maintenance of equipment, preparation and administration of radioactive medicinal products and the post processing of medical images.
Give examples of practical aspect.
- Calibration of equipment that emits ionising radiation
- Preparation of radioactive medicinal products
- Computer planning
- Calculation of monitor units used in radiotherapy
- Performing the exposure
Role of medical physics expert
Certificate of competence
Demonstrate underpinning knowledge, competence requires demonstration of practical experience in the following areas: - Compliance with IR(ME)R 2017
- Equipment management / Dosimetry -Technical specs.
- Optimisation - QA, acceptance testing, DRLs, incidents
- May need applications training
- Could also be RPA
What are the duties of practitioners, operators and referrers?
- Practitioner and Operator shall comply with employer’s written procedures
- Practitioner responsible for justification of medical exposure
- Practical aspects may be allocated to specific individuals (by employer or practitioner) who are then responsible
What are the different roles of operators and referrers?
- Operator will be responsible for each and every practical aspect which he/she carries out
- Referrer shall provide practitioner with sufficient medical data to enable the practitioner to decide on whether there is sufficient net benefit of such an exposure i.e. justification
Duties of employer, referrer, practitioner or operator.
- Practitioner and Operator shall cooperate, regarding practical aspects, with other specialists and staff involved in a medical exposure
- Any person who acts as employer, referrer, practitioner or operator must comply with the above duties
What is Diagnostic reference Levels?
Dose levels in medical radiodiagnostic practices or, in the case of radioactive medicinal products levels of activity, for typical examinations for groups of standard- sized patients for broadly defined types of equipment.
State the dose limit for Medical exposures
Dose limits do not apply to medical imaging exposures
- Diagnostic reference levels are recommended
- DRLs are published for Dose Area Product (DAP) and Entrance Surface Dose
(ESD) values for common examinations and projections
- Departments are expected to survey their own doses
- Investigations should be undertaken in X-ray departments where doses are found to exceed these levels
What are National DRLs?
- Reviewed at five-yearly intervals
- Medical physics to contribute patient dosimetry data to National Patient Dose
Database (NPDD)
- List of examinations for which there are National DRLs are being extended when sufficient data on UK practice has accrued
- There are now reference levels for more examinations National Diagnostic Reference Levels (NDRLs) Updated 19 August 2019)
What are the Local DRLs?
- Employers are responsible for setting local DRLs
- DRLs should be reviewed annually
- Provides a formal mechanism for revision of locally
adopted DRL values which may follow revised or new
national DRLs, or additions to local patient dose data - Where examination protocols have been changed, the
effect on the locally adopted DRLs should be considered
What happens when Dose is regularly exceeded?
- Investigation by Radiology manager and Medical Physics Expert (MPE)
- Performance of X-ray equipment
- Exposure protocols
- Technique and training of operator
- Look at level at which DRL has been set
List the Justification of individual medical exposure
Special attention shall be paid to:
- Specific objectives of exposure and characteristics of the individual
- Exposures that have no direct benefit for individuals undergoing the exposure
- Potential detriment to the individual
- Available alternative techniques
- The urgency of the procedure
What is Optimisation?
- Involves ensuring that doses arising from exposures are kept as low as reasonably practicable, but consistent with the intended purpose’
- In practice, optimisation is a process which relies heavily on professional competence and skill
What is ALARP in Optimisation?
As Low As Reasonably Practicable.
ALARP principle, operator must pay attention to the following when selecting equipment and techniques:
- QA (quality assurance)
- Assessment of patient dose
- Adherence to diagnostic reference levels (must be monitored)
When do practitioners and operators keep optimisation in mind?
Practitioner and operator must pay attention to:
- Medico-legal exposures
- Medical exposures of children
- Medical exposures in health screening programmes
- Medical exposures where pregnancy cannot be excluded
- In NM (nuclear medicine), breast feeding females undergoing medical exposures
List the other employer responsibilities.
- Clinical Audit - a way to find out if healthcare is being provided in line with standards and lets care providers and patients know where their service is doing well, and where there could be improvements.
- Expert Advice
- Equipment
- Training
