Dental Radiography Safety

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Dental Radiography Safety

• By Aggie Barlow, CHP, MS, MBA

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Goal

• The goal of dental radiography is to obtain
• useful diagnostic information while keeping
• radiation exposure to the patient and dental
• staff to a minimum.

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Digital Radiography in Dentistry

• Digital radiography was introduced in
• Dentistry in 1987. The technology has been
• gaining in acceptance, and in 2005 more than
• 22 of dentists were using digital
• radiography. 1

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Radiation Source

• A conventional x-ray tube is the source of
• X-radiation in most digital systems.
• Digital radiography requires 50-80 less
• radiation exposure in order to achieve an
• image compared to film systems.2

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Other Advantages

• No film, no darkroom and no chemicals are needed.
• No lead foil waste is generated.
• Digital radiography has superior gray scale
• resolution compared to conventional film.
• Digital images can be magnified.
• With the direct method, images appear immediately
• on the computer monitor.
• There is ease of information transfer to other
  dentists
• or insurance companies.

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MA Radiation Control Program Safety Regulations

• MA Regulations prohibit the deliberate
• exposure of an individual for training,
• demonstration or other non-healing arts
• purposes.

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Ordering Dental Radiographs

• Examinations must only be performed on direct
• prescription of a dentist, physician or other
• legally authorized provider. Dental radiographs
• must only be performed by Dentists or other
• legally qualified and credentialed personnel.

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Operator Location

• The operator of the dental unit must stand at
• least six feet from the useful beam or behind
• a protective barrier. Stand at an angle of from
  90 to
• 135 degrees from the central ray. Do NOT stand
  in
• the path of the primary x-ray beam.
• If a protective barrier is used, it must have a
  viewing
• window to allow the operator to see the patient.

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Personnel Radiation Badges

• MA Regulations state that individuals who
• operate only dental radiographic systems
• are exempt from the radiation badge
• requirements.

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X-ray Tube Housing

• The tube housing must not drift from its set
  position during an
• exposure. The tube housing must not be hand-held
  during an
• exposure by the operator or the patient due to
  leakage radiation
• through the tube housing.
• If you note problems with the tube housing,
  immediately
• report this to your supervisor so that any
  instability of the
• suspension arm can be corrected.

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Required Distances

• If the dental unit can operate above 50 kVp,
• the source to skin distance must be at least
• 18 cm 7 inches.
• The x-ray field must be limited to a circle
• having a diameter of no more than 7 cm 3 in.
• An open-ended beam indicating device must be used.

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Panoramic Units

• The beam must be limited to the imaging slit in
• the transverse axis and shall not exceed a total
• of 0.5 inches larger than the imaging slit in the
• vertical axis.

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Filtration Requirements

• The amount of filtration required varies with the
• operating range of the x-ray unit. For example
• For 51 to 70 kVp units .. 1.5 mm Al HVL
• Units above 70 kVp .. 2.1 or more Al
• Note Settings below 65 kVp are not recommended
• because of higher patient exposure.

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Technique Charts

• Written operating procedures and techniques
• must be available to all operators of dental
• units.
• Update each units technique chart regularly.

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Exposure Indicators

• Units must have dead man type exposure
• switches and indications of when an exposure
• is being made.

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Thyroid

• The thyroid gland, especially in children, is
• among the most radiosensitive organs.
• Even with optimum techniques, the primary
• dental beam may pass near or occasionally
• through the gland. A thyroid shield may
• reduce the dose to the gland without interfering
• with obtaining a diagnostic image.

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Lead aprons and shields

• Even though the dose from digital radiography is
  less
• than convention radiography, patients should be
• shielded with lead aprons and thyroid shields.
• These shields should have at least 0.5 mm of lead
• equivalent.
• Do not fold or bend aprons. Hang aprons to
• prevent damage and loss of protective qualities.

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Protection of others

• No one but the patient should be in the exam room
• during x-ray exposures. If a persons presence
  is
• necessary for the performance of the examination,
• that person must be behind a shield or wearing a
  lead
• apron. He/she must not be in line with the
  primary
• beam, and should stand at least six feet from the
• x-ray tube if feasible. He/she must also be at
  least
• 18 years of age and not be pregnant.

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Collimators

• Collimators limit the size and shape of the
• useful beam which reaches the patient.
• Rectangular collimators are recommended for
• periapical radiographs as their use significantly
• reduces the area of the patients body that
• is exposed to radiation.

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Cones

• The ADA discourages the use of short, closed,
• pointed cones because of the increased
• scatter radiation close to the face and adjacent
• areas of the patients body.

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System Speed

• Faster image receptor systems result in
• decreased radiation exposure to the patient.

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Notes

• Dental Products Report (DPR) Radiography A DPR
  Survey report. Dental Products Report 2005, May
  Accessed at www.dentalproducts.net/xml/display
  .asp?file2976
• Haring, J., Howarten, L., Dental Radiography
  Principles and Techniques, 3rd Edition.
• Philadelphia, Elsevier, 2006, 351-2

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Acknowledgement

• The image of the preferred 90 to 135 degree
• operator location was from
• Radiation Safety in Dental Radiography
• Eastman Kodak Company, 2004
• Rochester, NY, Health Imaging Division

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Additional Suggested Reading

• Radiation Protection in Dentistry
• NCRP Report 145, Oct. 2004, Bethesda

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For More Information

• Contact
• F.X. Masse Associates at [phone]
  
• or
• Tufts EHS at [phone].