Radiation Safety Regulations

Question 1

What is justification?

Answer 1

• Outlined in IR(ME)R17
• “No practice involving exposures to radiation should be adopted unless it produces sufficient benefit to the exposed individuals…. to offset the detriment it causes”.

Question 2

What is optimisation?

Answer 2

-“The magnitude of individual doses, the number of people exposed… should be kept ALARP” (whilst achieving the desired clinical outcome).

Question 3

What is limitation?

Answer 3

-“The exposure of individuals should be subject to dose limits. These are aimed at ensuring that no individual is exposed to radiation risks that are judged to be unacceptable… in any normal circumstances”.

Question 4

What are the international recommendations for radiation protection?

Answer 4

-International Commission for Radiological Protection 2008 (ICRP 2008).

Question 5

What is the UK legislation on safe work with ionising radiation? Which body enforces these regulations?

Answer 5

• IRR17: Apply to work activities; protection of staff and the public.
• Inspected and enforced by Health and Safety Executive (HSE).

Question 6

What is the UK legislation on medical exposures with ionising radiation? Which body enforces these regulations?

Answer 6

• IR(ME)R17: Apply to medical exposures; protection of the patient.
• Inspected and enforced by Care Quality Commission (CQC).

Question 7

Who is ultimately responsible for radiation protection measures?

Answer 7

-The employer.

Question 8

What things should the employer have in place when erecting a facility that will involve work with ionising radiation?

Answer 8

• Written radiation safety policy for occupational and medical exposures.
• Radiation protection committee.
• Appointment of RPA to ensure compliance with legislation. Physicist or corporate body.
• Radiation risk assessment.
• Critical examination of equipment (which has implications for radiation protection) following installation.
• Designate controlled areas to ensure exposures are adequately restricted.
• Local rules required for all areas to ensure proper restriction of access and safe working (adequate shielding).
• Appointment of RPS to ensure compliance with local rules.
• Appointment of classified persons if necessary.
• Personal monitoring for staff.
• Local dose constraints, to ensure legal dose limits are not exceeded.
• Dosimetry and investigation system in place for when certain dose levels or limits are exceeded.
• Reporting procedure for radiation incidents or accidents involving radiation in place.

Question 9

What is the new graded approach added to IRR17?

Answer 9

• IRR17 reg 5, 6, 7.
• Notification: low risk activities, notify HSE via electronic submission.
• Registration: e.g. all x-ray work, register with HSE via electronic submission, statements to agree to, small fee.
• Licensing/Consenting: High risk activities e.g. administration of radionuclides or use of linacs, require consent from HSE, more questions/evidence, higher fee.
• One application per practice per employer.

Question 10

State the dose limits for employees over 18.

Answer 10

• 20mSv whole body dose.
• 20mSv equivalent dose to lens of eye.
• 500mSv equivalent dose to the skin or extremities.

Question 11

State the dose limits for trainees under 18.

Answer 11

• 6mSv whole body dose.
• 15mSv equivalent dose to lens of eye.
• 150mSv equivalent dose to the skin or extremities.

Question 12

State the dose limits for “other persons”.

Answer 12

• 1mSv whole body dose.
• 15mSv equivalent dose to lens of eye.
• 50mSv equivalent dose to the skin or extremities.

Question 13

State the dose thresholds for classification of employees.

Answer 13

• 6mSv whole body dose.
• 15mSv equivalent dose to lens of eye.
• 150mSv equivalent dose to the skin or extremities.

Question 14

What dose classification of employees involve?

Answer 14

• IRR17 reg 21.
• Employee must be immediately informed of classification.
• They must undergo a medical examination by an appointed doctor to endure they are fit to work with ionising radiation.
• Regular medical surveillance.
• Personal monitoring by ADS.
• Personal dose information kept on CIDI (for at least 30 years).

Question 15

What are the types of doserate quantities used in radiation protection?

Answer 15

• Instantaneous dose rate (IDR): averaged over 1 min.
• Time-averaged dose rate (TADR): averaged over 8 hours, worst day case, occupancy factor of 1.
• Time-averaged dose rate over 2000 hours (TADR2000): averaged over 2000 hours, taking into account occupancy, use and workload.

Question 16

What are the guideline dose rate thresholds for designation of a controlled area?

Answer 16

• IDR > 100μSvhr^-1 [Guidance].
• TADR > 7.5μSvhr^-1 [ACOP].
• TADR2000 > 3μSvhr^-1 [Regulation].

Question 17

What are the guideline dose rate thresholds for designation of a supervised area?

Answer 17

• IDR > 7.5μSvhr^-1 [ACOP].
• TADR > 2.5μSvhr^-1 [Recommended].
• TADR2000 > 0.5μSvhr^-1 [Regulation].

Question 18

What are the guideline dose rate thresholds for unsupervised public areas?

Answer 18

• IDR > 7.5μSvhr^-1 [Recommended].
• TADR > 0.5μSvhr^-1 [Recommended].
• TADR2000 > 0.15μSvhr^-1 [Recommended].

Question 19

What is the hierarchy of control measures?

Answer 19

• Engineering controls.
• Systems of work/administrative controls.
• PPE

Question 20

Describe suitable warning signs for a controlled area.

Answer 20

• Fixed signs on door with radiation trefoil, stating e.g. ‘controlled area - x-rays’ and ‘risk from external radiation’.
• Illuminated 2 compartment signs, stating e.g. ‘controlled area - x-rays’ and ‘risk from external radiation’. Yellow side illuminated when unit switched on, red side illuminated when x-rays are being produced.

Question 21

How can access be restricted into a controlled area?

Answer 21

• Designate whole room as a controlled area.
• Physical barriers e.g. walls and door, interlocks on doors if necessary. Security measures to restrict access.
• No access to unauthorized persons.

Question 22

How is it ensured that the radiation levels to staff and the public are safe and well below dose limits?

Answer 22

• Environmental dose monitoring, e.g. TLD badges to confirm acceptability of radiation levels.
• Personal dose monitoring of staff to ensure dose thresholds and limits are not exceeded.

Question 23

What should Local Rules contain?

Answer 23

• Name of RPS(s) and RPA.
• Description of area and its identification as controlled or supervised.
• Arrangements to restrict access (e.g. warning signs).
• Conditions of entry for non-classified persons.
• Instructions for safe working to restrict exposure, e.g. PPE.
• Dose investigation levels.
• Contingency plans.

Question 24

What is an RPA and what advice do they give?

Answer 24

• Give advice on compliance with the regulations, including:
• Radiation risk assessment
• Designation of controlled and supervised areas.
• Handling of investigations.
• Contingency plans.
• Dose assessment and recording.

Question 25

What should an RPA be consulted on?

Answer 25

• Implementation of requirements for controlled and supervised areas.
• Plans for future radiation installations, modifications, design and safety features.
• Calibration and proper use of equipment for monitoring radiation.
• Periodic testing of control and safety features and systems of work.

Question 26

What is an RPS, who should be an RPS and what is their role?

Answer 26

• Appointed when local rules are needed in a radiation area.
• Preferably full-time employee of the department.
• Sufficiently senior to ensure day-to-day compliance with local rules, e.g. senior radiographer.
• Should liaise with head of department and RPA.
• Should understand precautions to be taken and what to do in an emergency.

Question 27

Give the general principles of patient protection.

Answer 27

• All diagnostic procedures carry some personal risk.
• Only necessary medical procedures should be carried out.
• Alternative methods using non-ionising radiation should be considered.
• All medical exposures must be justified.
• Diagnostic exposures must be optimised, ALARP.

Question 28

Name the three duty holders involved with a patients exposure.

Answer 28

• Referrer
• Practitioner
• Operator

Question 29

Who can act as a referrer and what is the minimum information they must supply?

Answer 29

• “A registered medical practitioner, 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”.
• Patient is uniquely identified.
• Clinical information to justify exposure.
• Information of pregnancy, LMP, Breastfeeding.
• Must provide signature (electronic allowed).

Question 30

Who can act as a practitioner and what is their role?

Answer 30

• “A registered medical practitioner, dental practitioner or other health professional who is entitled in accordance with the employer’s procedures to take responsibility for an individual medical exposure”.
• Confirms justification of exposure.
• Authorizes the request.
• Usually consultant radiologist etc.
• Authorizing the exposure can be delegated to an operator.
• For radionuclide procedures, practitioner must hold an ARSAC licence. [and employer for each site].

Question 31

Who can act as an operator and what is their role?

Answer 31

• Any person who carries out practical aspects of an exposure e.g.:
• Handling and use of radiological equipment.
• Assessment of doses.
• Calibration and maintenance of equipment.
• Preparation and administration of radioactive products.
• Operators must be identified in procedures.
• Practitioner can also act as the operator (fluoro).
• any procedures will involve more than one operator.
• Operators optimize the exposure for each patient.

Question 32

What is an MPE?

Answer 32

• Recognised by the competent authority.
• Closely involved in radiotherapy procedures.
• Involved in nuclear medicine procedures and high dose CT and interventional procedures.
• Available under contract and involved as appropriate in other radiological practices.

Question 33

What are local diagnostic reference levels and how are they determined?

Answer 33

• Established for each standard diagnostic and nuclear medicine examination for “standard sized” patients.
• Median values for ESD, DAP, mAs, screening time etc.
• Determined from local dose audit - data may be taken from RIS/PACS.
• Should be reviewed at least every three years or when changes made to equipment or procedures.
• Investigation required if patient doses regularly exceed DRL.

Question 34

What are national diagnostic reference levels and how are they obtained?

Answer 34

• Obtained from a national survey of local diagnostic reference levels.
• NDRL taken to be the upper-quartile (75th percentile) of the distribution of local DRLs from survey for each examination and “standard sized” patients.
• If a centre has local DRLs that are consistently greater than the NDRLs then equipment may not be optimized.

Question 35

What should be done if a patient undergoes an accidental or unintended exposure?

Answer 35

• Incident must be documented, investigated and reported.
• Person at fault should be given advice on how to prevent this incident occurring again.
• If classed as a ‘significant accidental or unintended exposure’, need to notify the exposure to the CQC.

Question 36

What are the general steps involved in a patient dose incident?

Answer 36

• Determine effective dose to patient [mSv].
• Determine the background equivalent timescale.
• Determine the broad level risk due to this exposure and apply factors of age and sex if required.
• Determine the action required for this exposure (e.g. reportable to CQC?).
• Give advice on how to prevent this incident happening again.

Question 37

What 3 things are required if carrying out research using ionising radiation?

Answer 37

• Local Research Ethics Committee approval must be obtained.
• Dose constraints must be established.
• Generic risk assessments must be performed and communicated to volunteers.

Question 38

What are comforters and carers and what must be communicated to them?

Answer 38

• “Relatives or friends of a patient who act in a supporting role and ‘knowingly and willingly’ incur an exposure”.
• Must be informed of the risks.
• Must be informed of special procedures to restrict their exposure.
• Must willingly accept the dose and risk involved.
• Exposures should be ALARP.
• Dose constraints must be set.
• Pregnant woman should normally be excluded.

Question 39

What measures can be taken by diagnostic radiology staff to reduce their dose?

Answer 39

• Keep as much distance from the patient as possible.
• Collimate the beam to only expose region of diagnostic interest (this will reduce dose to patient and scatter to staff).
• Wear PPE (e.g. apron) or stand behind shielded screen.

Question 40

What measures can be taken by diagnostic radiology staff to reduce dose to the patient?

Answer 40

• Only direct beam to those areas being examined.
• Avoid irradiation of sensitive organs unless essential.
• Optimise technique for women known or likely to be pregnant.
• Keep tube leakage ALARP (<1mGyhr^-1 at 1m).
• Use suitable filtration (filtraion >2.5mmAl for DR).

Question 41

State the safety features of a DR equipment (planar, fluoro, CT etc).

Answer 41

• Image receptors should have 2.5mm lead shielding (150KV).
• Last image hold.
• Exposure factors and switches:
• Automatic dose rate control.
• Radiographic equipment should have AEC.
• CT scanners should have adequate range of mAs selections.
• Exposure switches should require continuous pressure to be maintained (excludes scanners).
• Beam size:
• Collimate beam.
• Light beam diaphragm.
• Confine radiation beam within image receptor and to area of interest.

Question 42

How can protocol help limit the dose to patients?

Answer 42

• Standardised where possible with appropriate KV/mA/AEC setting.
• Paediatric protocols available.
• Pulsed fluoroscopy whenever possible.
• Appropriate use of axquisitions in fluoro exams.

Question 43

What exposure factors can we obtain from DR equipment after a procedure?

Answer 43

• All AEC should give display mAs post-exposure.
• All equipment to give indication of patient dose e.g. DAP/DLP.
• Equipment for interventional radiology should give indication of cumulative skin dose to patient.