Ionising Radiations Regulations 1999 IRR99

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Ionising Radiations Regulations 1999 (IRR99)

• Craig Moore
• Physicist

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What are the IRR99 Regulations for?

• Protection of
• Staff
• Public
• from ionising radiation such as X rays
• The regulations also stipulate the need for
  equipment quality assurance for protection of the
  patient
• Enforced by the Health and Safety Executive

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Whats the Point in Legislating?

• Ionising radiation can cause the following
  effects
• Deterministic effects such as skin erythema (we
  will never see this in dental radiography)
• Stochastic effects
• 1 in 20,000 risk of fatal cancer
• 1 in 100,000 risk of non fatal cancer
• 1 in 77,000 risk of hereditary effects
• Per mSv
• Ionising radiations is invisible so you cant see
  or smell it, hence it can cause damage without
  you knowing about it (at first!!!)
• General philosophy
• Justification
• Optimisation
• Limitation

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So whats included in IRR99?

• General Principles and Procedures
• Arrangements for the Management of Radiation
  Protection
• Designated Areas
• Classification and Monitoring of Persons
• Arrangements for the Control of Radioactive
  Substances
• Duties of Employees

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General Principles and Procedures

• Prior authorisation (and notifiation) must be
  sought from the HSE before any work with X ray
  equipment can be carried out
• A Prior Risk Assessment must be carried out
  before any work with X rays. New activities
  involving work with ionising radiation is not
  permitted in British Law unless a sufficient risk
  assessment has been made
• Restriction of exposure
• Dose constraints
• Upper level of individual dose specified by the
  employer
• 1 mSv per year for dental radiographers
• Personal Protective Equipment such as lead apron
  or gloves

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General Principles and Procedures

• Dose limitation (Jan Dec) ALARP

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Other Limits

• The foetus of a pregnant women must not receive
  more than 1 mSv from notification of pregnancy
• NRPB state that to achieve this, dose to the
  abdomen should not exceed 2 mSv from notification
• There is no limit for Comforters and Carers or
  patients

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Comforters and Carers

• These are individuals who (other than as part of
  their profession), knowingly and willingly incur
  an exposure to ionising radiation in the support
  or comfort of another person who is undergoing,
  or has undergone a medical exposure
• A dose constraint is required however.

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Classified Workers

• This is anyone who may exceed 6 mSv/y, or 3/10th
  the relevant dose limit
• Must be informed that they are a classified
  worker
• 18 or over
• Certified fit to work by Doctor
• Dose records kept for 50 years
• No dental radiographers will ever need to be a
  classified worker

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Female Patients of Child Bearing Age

• In dental radiography, the vast majority of
  projections are not directed towards the pelvic
  area
• Because of the very small doses involved, risks
  are negligible
• However, because of emotive nature of radiography
  during pregnancy, the patient may be given the
  option of delaying exposure

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Management of Radiation Protection

• Radiation Protection Advisor (RPA)
• An RPA must be appointed in writing be a
  radiation employer
• Implementation of requirements as to controlled
  areas
• Prior examination of plans and commissioning/criti
  cal examination of new radiation producing
  equipment
• Regular calibration of equipment that produces
  ionising radiation
• Periodic critical examination
• Radiation risk assessments
• Local Rules
• Dose assessment and recording
• PPE
• Staff training
• Routine Quality Assurance
• Staff training
• Information for pregnant and breastfeeding
  employees
• Radiopharmacy design
• Training for emergencies

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Controlled Areas

• This is an area where it is necessary to follow
  special procedures to restrict exposure to
  ionising radiation, or
• An area where any person is likely to receive
  3/10th of the dose limit or more
• In dental radiography, the controlled area only
  exists whilst X rays are being generated, and
• Is in the primary beam
• Is within 1.5 m from the X ray tube and the
  patient (we usually state 2 m)
• A supervised area is any area where it is
  necessary to keep conditions under review, or
  where it is possible for a person to receive a
  dose gt 1 mSv/y or 1/10th the dose limit. No
  dental radiography rooms need to have designated
  supervised areas

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How are Exposures in the Controlled Area
Minimised in Practice? Local Rules

• Local Rules must be written and adhered to for
  every radiation controlled area
• Essential contents of local rules include
• Dose investigation level
• Contingency arrangements
• Name of radiation protection supervisor
• Identification of area covered
• Working instructions
• Local rules may also contain management and
  supervision of the work
• Testing of engineering controls
• Radiation monitoring
• Testing of monitoring equipment
• Personal dosimetry
• Arrangement for pregnant and breastfeeding staff

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Local Rules

• Before anyone can enter a controlled area, they
  must either be a classified worker (none of you
  will be), or have read and understood the local
  rules
• We usually get new employees to read and sign to
  say they have read the local rules before they
  are allowed to enter a controlled area you will
  too!!!

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Radiation Protection Supervisor

• These are appointed by the radiation employer for
  the purpose of ensuring compliance with these
  regulations
• They essentially make sure local rules are
  adhered to and govern the Controlled Area

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Dose Monitoring

• Most employees who work with radiation in the
  Trust have radiation monitoring badges.
• These monitors the exposure to radiation of an
  employee
• Dental radiographers tend to wear badges if a
  risk assessment indicates their dose could exceed
  1 mSv/y (usually gt100 intra-oral and gt 50
  pan-oral exposures per week)
• Doses received are assessed by the RPA to ensure
  they are being kept ALARP

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Notification of Incidents

• Must report to HSE when the dose to a patient is
  much greater than intended
• x 20 for Dental
• If it was a machine fault this must be reported
  to the HSE
• If any other fault (e.g. radiographer) then
  inform Dept of Health

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Incidents

• Any untoward occurrence that may have resulted in
  excess radiation to staff or patients must be
  referred to the RPS and RPA
• The RPA will estimate the dose and inform
  management, HSE, DoH etc if necessary
• Suspect equipment must be withdrawn from service
  and labelled acordingly.

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Investigation

• Establish what happened
• Identify the failure
• Decide on remedial action to minimise chance of
  occurrence in the future
• Estimate doses involved
• Decide whether the patient needs informing