Controlling exposure of staff and other people

Conduct a radiation risk assessment, in consultation with your RPA, to identify the control measures required to restrict the exposure of staff, patients and the public to radiation and, as with all health and safety requirements, act on the findings.

• The ‘Guidance Notes for Dental Practitioners on the Safe Use of X-ray Equipment’ [3] provide details of the aspects that should be considered in the radiation risk assessment.
• The risk assessment should include estimates of the doses to members of the public resulting from the work with x-rays carried out at the practice.

Keep the written risk assessment in your Radiation Protection File.

Review the risk assessment at 3-yearly intervals and more frequently if there are changes in equipment, working methods or legislation that may have radiation safety implications.

NB: It is a legal requirement to record the significant findings of the risk assessment if 5 or more members of staff work in the practice; however, all practices are strongly advised to do this.

As part of your risk assessment, determine the contingency plans that are necessary to address reasonably foreseeable accidents, such as failure of the x-ray control circuitry or of the rotational movement of panoramic equipment. Include in these plans how staff should deal with equipment malfunctions and other incidents. Record the contingency plans in your Local Rules and rehearse the arrangements in the plans at suitable intervals (e.g. annually)

In consultation with your RPA define the controlled area(s), which is the site(s) where the practice’s x-ray equipment is when operated, and record this as part of the Local Rules.

• Where possible, the whole room should be designated as the controlled area while the equipment is in a state of readiness to emit X-rays, with the room boundaries demarcating the area. Alternatively, the controlled area may be designated as 1.5 m from the x-ray tube head and the patient in all directions and within the primary beam until it is sufficiently attenuated by shielding or distance.
• The whole room should be defined as a controlled area for CBCT use [3].
• Where practicable, controlled areas should be physically demarcated.
• The most appropriate method to assess levels of transmitted and scattered radiation at the boundaries of the controlled area should be determined in consultation with the RPA, and documented in the risk assessment [3].
• For hand-held x-ray machines refer to relevant guidance [3,4].
• Your RPA will advise on the necessary warning signs and lights. Documenting this advice may be helpful for inspection purposes. The ‘Guidance Notes for Dental Practitioners on the Safe Use of X-ray Equipment’ [3] include detailed advice on dental X-ray room warning signs and lights.

Position the equipment so that the tube warning light and the patient are visible to the Operator during the exposure, and  position control panels, exposure switches, mains isolators and power switches outside the controlled area if possible.

Consult with your RPA to ensure that there is adequate protection for those outside the controlled area.

• Lead shielding should be provided for partition walls, if required (brick attenuates the beam in most instances).

Ensure no one other than the patient, and the carer or comforter if necessary, is in the controlled area during exposure time, and that the operator stands well outside the controlled area (e.g. at least 2 metres away from the tube head and the patient) and out of the direction of the primary beam.

Put in place a Dose Investigation Level for your practice and record this in the Local Rules. The recommended annual limit for employees directly involved with radiography is 1 mSv.

Consult with your RPA if any member of staff receives, or is suspected to have received, an annual dose in excess of the Dose Investigation Level, carry out a formal investigation of the exposure and record the results in the Radiation Protection File.

Consult with your RPA for advice on whether personal dosimetry is required for members of staff.

• This decision will depend on local circumstances and your RPA should be able to justify the advice given as part of the risk assessment.
• For operators or other non-classified persons who need to enter the controlled area, the doses must be assessed to confirm that the written arrangements are effective in adequately restricting their exposure [3].
• Keep reports of any personal dosimetry in the Radiation Protection File.
• Staff must have adequate training and instruction about the care and proper use of any dosemeters provided.

Review the work and likely radiation dose of pregnant members of staff to ensure the dose to the foetus is unlikely to exceed 1 mSv during the declared term of the pregnancy.