18

Radiation Protection

Introduction – Principles of Radiation Protection

The information provided in this chapter is designed to supplement and support the Radiation Protection Quality Assurance Manual used in all dental practices. This chapter is not intended to replace the manual and therefore at all times you should refer to and adhere to the quality assurance process as set out in the manual.

Although the risks associated with dental radiography are small in comparison to medical radiography, there remains a legal requirement to minimise the risk as far as is reasonably practicable. The principles of radiation protection can be classified into three categories; principles of justification, principles of optimisation and principles of limitation.

• Justification
  • The need for the use of radiation must be clearly identified prior to use.
  • The benefits of the use of radiation must outweigh the risks involved.
• Optimisation
  • The as low as reasonably achievable/practicable (ALARA/P) principle should be applied, keeping the dose of radiation used as low as is commensurate with a usable image.
• Limitation
  • The exposure of employees and patients should not exceed dose limits.
  • The need for retakes should be kept to an absolute minimum.
  • Safe practices should be adopted for staff involved with radiation procedures.

Legislation

• Ionising Radiation Regulations 1999 (IRR 1999):

  Every radiation employer shall, in relation to any work with ionising radiation that he undertakes, take all necessary steps to restrict so far as is reasonably practicable the extent to which employees and other persons are exposed to ionising radiation.

• Ionising Radiation (Medical Exposure) Regulations 2000 (IRMER 2000):

  The Regulations impose duties on those responsible for administering ionising radiation to protect persons undergoing medical exposure whether as part of their own medical diagnosis or treatment or as part of occupational health surveillance, health screening, voluntary participation in research or medico-legal procedures.

• The Management of Health and Safety at Work Regulations 1999:

  Employers [are] to make suitable and sufficient assessments of risks to health and safety of employees to identify the measures needed to remove the risks or reduce to an acceptable level.

Ionising Radiation Safety

• Authorisation must be granted by the Health and Safety Executive (HSE) for an employer to use electrical equipment intended to produce X-rays for the purpose of the exposure of patients for medical treatment.
• Notification of such use, or change of use, should be made in writing and contain the following information:
  • The name and address of the employer and a contact telephone or fax number or electronic mail address
  • The address of the premises where or from where the work activity is to be carried out and a telephone or fax number or electronic mail address at such premises
  • The nature of the business of the employer
  • That the source of the radiation is an electrical equipment
  • Whether any source is to be used at premises other than the address given above
  • Dates of notification and commencement of the work activity

A form, IRR3 Notification of Intention to Carry Out Site-Radiography – Ionising Radiation Regulations 1999 (Regulation 6(3), can be completed and sent to HSE Phoenix House, 23-25 Cantelupe Road, East Grinstead, West Sussex, RH19 3BE).

Notification must be received by HSE at least 7 working days in advance of commencement of work.

• Prior (proactive) risk assessment must be done when new X-ray equipment is planned, existing equipment is modified and when equipment is relocated.
• A suitable and sufficient assessment of the risk to any employee and other person must be carried out.
• Employers must adhere to dose limitations for women who are expecting or breastfeeding. Doses must not exceed 1 mSv to reduce the risk of bodily contamination. Employers should strongly encourage their staff to inform them as soon as pregnancy is confirmed by a medical practitioner. Women must be informed of the risks and control measures applied. Risk assessments should be reviewed and revised if necessary according to individual needs.
• Following annual dose limitations must not be exceeded (IRR99):
  • Employees over 18 years 20 mSV
  • Trainees aged under 186 mSv
  • Persons under the age of 16 1 mSv

Exposure must be restricted, where, reasonably practicable, below these limits.

• Contingency plans must be in place to address foreseeable accidents arising from the use of X-ray equipment.
• Appointment of (in writing) and consultation with a radiation protection advisor (RPA) should take place to ensure compliance with the regulations.
• Identify the need for and involvement of a medical physics expert (MPE) to advise on patient doses (the MPE may also act as the RPA).
• Appoint one or more radiation protection supervisors (RPSs) to assist with compliance; this can be a dentist or dental nurse. The appointee must be competent to supervise the arrangements set out in local rules. Responsibilities may include the following:
  • Providing support to staff on matters relating to radiation safety
  • Maintaining the radiation staff register (Figure 18.1)

    Figure 18.1 Radiation staff register.

    

  • Ensuring risk assessments are valid, current, suitable and sufficient in detail
  • Assessing and identifying training needs
  • Managing dose meter monitoring procedures
  • Ensuring X-ray equipment is functioning correctly
  • Reporting any defects or areas for concern
  • Ensuring quality assurance and radiation safety is being implemented at all times
• Identify persons who are required to act as ‘operators’ to assist with practical aspects of radiation procedures. Responsibilities may include the following:
  • Positioning the film, patient and X-ray tube head
  • Setting and directing the exposure (press the button)
  • Processing and storing films
  • Exposing test objects
• Designate staff as ‘classified persons’ if they are required to enter the controlled area; however, this is unlikely to be required.
• Employees who are engaged in work with ionising radiation are given appropriate training in the field of radiation. Training should include
  • the risks to health created by exposure to ionising radiation;
  • the precautions which should be taken; the importance of complying with the medical, technical and administrative requirements of the regulations; and
  • updation every 5 years covering topics recommended by statutory bodies.
• Every employer shall designate as a controlled area any area where steps need to be taken to minimise the risks of exposure to ionising radiation.
• Every employer shall consider the environment where ionising radiation is being directed and install appropriate physical barriers – for example, lead-lined and double-bricked walls and position equipment to reduce the risk of exposure to all persons.
• Every employer shall make and set down in writing such local rules as are appropriate to the radiation risk and the nature of the operations undertaken in that area.
• No person shall carry out a medical exposure unless it has been justified by the practitioner as showing a sufficient net benefit.
• In relation to all medical exposures to which the regulations apply the practitioner and the operator shall ensure that doses arising from the exposure are kept ALARP, consistent with the intended purpose.
• The employer shall draw up, keep up to date and preserve at each radiological installation an inventory of equipment at that installation and, when so requested, submit it to the appropriate authority. Information required includes
  • name of manufacturer;
  • model number;
  • serial number or other unique identifier;
  • year of manufacture; and
  • year of installation.
• No practitioner or operator shall carry out a medical exposure or any practical aspect without having been adequately trained. This requirement does not prevent a person from participating in practical aspects of the procedure as part of practical training if this is done under the supervision of a person who himself/herself is adequately trained.
• The employer shall keep and have available for inspection by the appropriate authority an up to date record of all staff who have a responsibility for ionising radiation, in particular, radiation practitioners and operators engaged by him/her to carry out medical exposures. All of the above must have clearly defined tasks and permitted duties written down using actual names (Figure 18.1).
• Dose measurement services should be provided where applicable – for example, where it is suspected that individuals may receive dose levels that exceed 6 mSV per year. However, employers should be reducing these doses as low as is reasonable.

Quality Assurance and Risk Control

Quality assurance programmes in dental radiography are designed to ensure that the principles of ALARA/P are applied effectively and should be comprehensive and inexpensive. The procedure adopted in the workplace should

• be documented;
• be the responsibility of a named person;
• use preferred methods of producing radiographs – the use of film holders as routine practice;
• monitor image quality – a simple subjective grading system is recommended and should form part of the continual improvement target setting process. For example,
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