Radiation Risk

Question 1

What are the benefits and risks associated with the job of a radiation worker? How are the risks mitigated?

Answer 1

Benefits:
- Employment.
- Sense of well-being from helping others (e.g. when working with radiation in the medical sector).
Risks:
- Negative health effects associated with exposure to ionising radiation.
- These risks should be comparable to other work activities.

Risks are mitigated with dose limitation, optimisation (ALARP) and additional controls for those receiving higher doses (controlled workers)

Question 2

What are the benefits and risks associated with medical radiation exposure to patients? How are the risks mitigated?

Answer 2

Benefits:
- Medical diagnosis/treatment.
Risks:
- Negative health effects associated with exposure to ionising radiation.

Risks are balanced against the measurable benefit in the IR(ME)R justification and optimisation processes.

Question 3

What are the benefits and risks associated with public exposure to radiation? How are these balanced?

Answer 3

Benefits:
- There are no direct benefits to public exposure.
Risks:
- Negative health effects associated with exposure to ionising radiation.

The risks are considered acceptable when compared to other risks from everyday life. Dose limits are applied.

Question 4

What are the benefits and risks associated with emergency exposure situations? How are these balanced?

Answer 4

Benefits:
- Alleviation of greater risk or risk to a greater number of people.
Risks:
- Negative health effects associated with exposure to ionising radiation (potential to be a high exposures).

Risks are balanced against the risks of taking no action at all. The ALARP principle is still applied, although dose limitation is typically relaxed. Dose reference levels are applied instead.

Question 5

What is a man-Sievert?

Answer 5

The ALARP principle allows for economic considerations to be taken into account. The man-Sievert is a value proposed to assign a monetary value to the economic benefit and detriment regarding a radiation exposure. It considers net benefit using the following equation:
Net benefit = Gross benefit - Production cost - Cost of protection - Detriment. This could potentially be used in the justification of practices.

Question 6

What are the requirements of a radiation risk assessment?

Answer 6

• Required under the Management of Health & Safety at Work Regulations.
• Requirement of IRR17 for work with radiation.
• Conducted prior to the commencement of work.
• Should cover routine work and foreseeable accidents.
• Should be a written record.
• Should be reviewed/updated when procedures change or at least 3 yearly.

Question 7

List three sources of guidance for radiation risk assessments.

Answer 7

• Medical & Dental Guidance Notes.
• IRR17 Approved Code of Practice.
• Five Steps to Risk Assessment.

Question 8

What are the Five Steps to Risk Assessment?

Answer 8

• Identify hazard.
• Decide who might be harmed and how.
• Evaluate risks (with numerical calculations) and decide whether existing controls are adequate.
• Record findings.
• Review and revise.

Question 9

When are risk assessments required?

Answer 9

• New facilities.
• New radioactive sources.
• New equipment.
• New use of existing equipment.
• New working practices.
• Significant changes in staff or workload.
• Regular routine review.

Question 10

What headings should be considered as part of a risk assessment, as per IRR17?

Answer 10

• Location of work.
• Description of work.
• Source(s) of radiation.
• Estimated radiation dose rates.
• Advice from the manufacturer.
• Contamination.
• Control measures.
• Exposed groups from routine work.
• Accidental exposures.
• Failure of control measures.
• Non-routine exposures.
• Evaluation of risks from routine and non-routine work.
• Actions to be taken.
• Contingency plans.

Question 11

Give some examples of different ‘locations of work’, as per IRR17 for a risk assessments.

Answer 11

• For one particular room.
• For one particular activity (e.g. CT fluoroscopy).
• For one particular area (e.g. Nuclear Medicine department).
• This is not overly prescriptive and will depend on the specific situation as to what is most appropriate.

Question 12

What must be considered for a risk assessment ‘description of work’, as per IRR17?

Answer 12

• Everything that is done with the equipment or within the room (e.g. Maintenance/QA, cleaning/estates work, non-standard use etc.).
• Consider how exposures are carried out and where those involved are located at different parts of the process.

Question 13

What aspects of the sources of radiation must be considered for a risk assessment, as per IRR17?

Answer 13

• Primary source (e.g. x-rays, sealed sources, unsealed source etc.). This could also include the patient after a radiopharmaceutical injection.
• Expected and possible energies of emitted radiation.
• Scatter sources (e.g. the patient).
• Other additional sources (e.g. neutron activation in radiotherapy linacs).
• Unintended sources (e.g. source shielding failure).

Question 14

What should be considered when estimating radiation doses for a risk assessment, as per IRR17?

Answer 14

• Dose rates to which people are likely to be exposed.
• Maximum dose rates from primary beam.
• Typical distance from the source.
• Workload and occupancies.
• Extent of unrestricted access when dose rates are significant.

Question 15

What manufacturer advice might be included in a risk assessment, as per IRR17?

Answer 15

• Requirement for maintenance and QA.
• Safe operating instructions.
• Any limitations on use.

Question 16

What information on contamination should be included in a risk assessment, as per IRR17?

Answer 16

• Likelihood of contamination arising.
• Likelihood of it being spread.
• Estimated levels (airborne and surface).

Question 17

What information on control measures already in place should be included in a risk assessment, as per IRR17?

Answer 17

• Engineering controls and design features (e.g. shielding, interlocks etc.).
• Systems of work.
• PPE and effectiveness and suitability.
• Results of any previous personal dosimetry or are monitoring.

Question 18

Which exposed groups are likely to be considered in a risk assessment, as per IRR17? Which exposed groups are not?

Answer 18

• Usual staff (e.g. radiographers).
• Other staff (e.g. clinicians, porters, sales reps, engineers, medical physics etc.).
• Visitors/public.
• Patient will not be covered as they will be covered in more detail under IR(ME)R.

Question 19

What is a ‘radiation accident’ considered in a risk assessment as per IRR17? Provide some examples. What is required in case of a radiation accident?

Answer 19

• Radiation accident: An accident where immediate action is required to prevent or reduce the exposure to ionising radiation of employees or any other person.
• e.g. Failure of equipment to terminate exposure, accidental activation of fluoroscopy foot switch when not in use etc.
• Contingency plans are required in the case of a radiation accident. HSE must also be notified if a radiation accident occurs.

Question 20

What is a failure of control measures considered in a risk assessment, as per IRR17? How are these different to radiation accidents?

Answer 20

• A failure of control measures is less serious than a radiation accident and typically does not required reporting to HSE. They do still require action plans.
• e.g. Person walking into room who was not meant to, failure of warning light, procedures not followed etc.

Question 21

What should be considered in terms of non-routine exposures in a risk assessment, as per IRR17? What are examples of non-routine exposures?

Answer 21

• Non-routine exposures are typically those associated with a radiation accident or a failure in control measures.
• Groups involved (e.g. staff and public).
• Where they will be and for what length of time they are exposed.
• Worst-case scenario’s should be considered but reasonable assumptions should be made with regards to response times etc. to ensure dose estimates do not become over the top.

Question 22

How is the risk associated with routine exposures evaluated in a risk assessment, as per IRR17?

Answer 22

Dose estimates are made with consideration of the following:
- Dose rates from source.
- Dose rates from scatter.
- Distance of exposed individual from source.
- Time spent at this distance.
- Any shielding/PPE used (assumptions may be required regarding effectiveness).
- Typical average values should be used so to not overestimate.
- Practical simulation could be used.
- Existing dosimetry can be used, if available.
- Use of risk matrices.

Question 23

What should be considered when determining actions that need to be taken as a result of a risk assessment, as per IRR17?

Answer 23

• Whether predicted exposures are within dose limits/classification levels.
• Whether predicted exposures ALARP.
• Special categories of people (e.g. pregnant individuals, young people, trainees etc.).
• Personal dosimetry requirements.
• Dose investigation levels (should be set to determine if any exposures are not ALARP).
• Additional engineering controls.
• Additional PPE.
• Additional procedural controls (e.g. doors to be locked, equipment orientation etc.).
• Specific dose constraints.

Question 24

When are contingency plans required and when are action plans required?

Answer 24

Contingency plans are required for reasonably foreseeable radiation accidents. Actions plans are required for failure of control measures.

Question 25

What should be considered regarding contingency plans in a risk assessment, as per IRR17?

Answer 25

• Are they sufficient?
• Do they need to be rehearsed and how often?
• Is additional training in contingency plans required?
• Are contingency plans well documented?

Question 26

Aside from the main headings of a risk assessment, as per IRR17, what else should be considered and what should happen once the risk assessment s complete?

Answer 26

• Review frequency.
• Document control.
• Conclusions should be used to feed into the local rules.
• Must go to management and be disseminated to the appropriate staff.

Question 27

How may information be collected to feed into a risk assessment?

Answer 27

• Talk to involved staff.
• Observation of procedures.
• Auditing of technique/dose data.
• Establish good communication so any changes are brought to attention.

Question 28

Who is responsible for a risk assessment? Who performs the risk assessment?

Answer 28

The employer is responsible but the risk assessment is typically undertaken with RPA advice and input from local staff (e.g. RPS).

Question 29

What should be considered when communicating risk?

Answer 29

• Audience (e.g. patient or staff member) and their knowledge level/degree of involvement.
• Specification of the risk (i.e. cancer incidence, cancer fatality, health detriment etc.).
• Uncertainty in estimate (use appropriate rounding/significant figures).
• Context of risks (e.g. comparison with baseline, natural background or other well-established risks).
• Benefit of an exposure (e.g. diagnosis/treatment).
• The situation (i.e. whether it is a high stress or low stress situation). In high-stress situations, risk communication should be as simple as possible with a focus on empathy and positives.