Radiation protection of staff in dental radiology

» What are typical staff dose levels in dental radiology?

Employees performing dental radiography should not normally receive significant radiation dose provided normal radiation protection measures are employed, such as distance and shielding. A report from UK estimates a mean level of less than 0.1 mSv per year, in the practice conditions that prevail there. In the USA the mean dose received by dental workers is reported to be 0.2 mSv. 

For CBCT, in the absence of shielding, scatter doses between 4.1 and 46.8 µSv at 1 m have been reported; therefore, this modality should be installed in a protected enclosure. 

» Is there a need for personnel monitoring in dental practice?

Given the low doses received by staff involved in dental radiography, routine personnel monitoring is generally considered to be desirable but not necessary. Different national regulationsshould be taken into consideration. UK guidance recommends that monitoring is not normally required unless the risk assessment indicates that individual doses are likely to exceed 1 mSv per year. However, national guidance in other countries recommends personal monitoring for all dental practices using X-ray equipment. Where regulations do not require individual personnel monitoring, it may be valuable to monitor the practice through monitoring one or more individuals from time to time.

Further information:

» Can a pregnant employee continue to work in the dental radiology department?

It is unusual for any member of staff in dentistry to get the foetal dose limit of 1 mSv from work. A female staff member should understand the importance of notifying her employer if she becomes pregnant. If notified, the employer should ensure that the pregnant employee’s working conditions are optimised and that the prescribed dose limits are not exceeded. Generally, the working conditions, after declaration of pregnancy, should be such that it is unlikely that the foetal dose will exceed 1 mSv during the remainder of the pregnancy. In a dental setting, extensive modifications of the working environment are usually not needed; general protection measures (e.g. personal shielding) suffice. A qualified expert can be contacted to estimate the projected foetal dose based on equipment factors and workload. 

» Who should hold dental film during radiography?

Film should not be hand held by a member of the dental practice staff. If necessary it should be held by the patient, but only when it cannot otherwise be kept in position. If the patient can not hold it, and a comforter/carer must be involved, then this should be done using forceps or other device (eg., a specifically designed dental film holder) so that fingers are not in primary beam.

» When should portable (handheld) intra-oral radiography equipment be used? 

Handheld portable X ray equipment for intraoral radiography should be used only for examinations where it is impractical or not medically acceptable to transfer patients to a fixed unit. Examples are patients in nursing homes, residential care facilities or homes for persons with disabilities; in forensic practice; or for military operations abroad without dental facilities. The use of portable X ray equipment in other settings (e.g. dental clinic) is discouraged.

» Is it necessary to provide structural shielding in dental radiography department?

The purpose of facility design includes ensuring that prescribed dose limits are not exceeded. 
This requires consideration of workload, the size of the facility, the duration for which people are in the surrounding area, and is best achieved with the advice of a radiation protection expert. Formal approval and/or licensing for the structural shielding and other radiation safety measures may be required, depending on national regulations.

» Who may be present in the room during radiographic exposure? 

In the case of a single-chair room, persons must not be present in the room during a radiographic exposure unless their presence is necessary for conduct of the examinations. 
Persons present must be located behind a shield allowing a view of the patient and the “exposure on” indicator, or wearing protective apron, or at least 2 m from the source of scattered radiation, i.e. the patients head, and not in line with the primary beam. In the case of the multi-chair room, there should be adequate shielding between the chairs.

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