Diagnostic and treatment of many conditions and diseases can be made easier by dental x-rays. Although radiation from xrays is very low, it can build up from many sources over time. These simple methods can help limit radiation exposure.
Protection of the patient
Reviewing previous full-mouth or panoramic radiographs can help to eliminate the need for new radiographs. Patients with good periodontal health may be able increase the frequency of bitewings from once a year to every 18 to 24 month years. Radiation exposure can be reduced by using higher film speeds, shielding, collimation, or if new radiographs are required.
HIGHER FILM SPEEDS – Using the most efficient film possible significantly reduces radiation exposure. There are three types of intraoral Xray film currently available: D, E and F. E speed film is almost twice the speed of D-speed film, and about 50 times faster that traditional xray film. F-speed film is 25% more exposed than E-speed films and requires 60% less exposure as D-speed films. Multiple studies have shown that F-speed film is as useful in terms of density, latitude, contrast and image quality than D- and E’speed films. It can also be used for routine intraoral radiographic examinations without losing diagnostic information.
SHIELDING: Thyroid collars and aprons protect the thyroid gland and gonads from radiation. This is especially important for pregnant women and children. According to the ADA, every patient should wear an apron. A thyroid collar is recommended for routine bitewing and periapical radiographs. Panoramic imaging can be a exception. A thyroid collar can mask large areas of the target area.
COLLIMATION: A collimator, a metal barrier with an opening at the center, is used to reduce both the beam’s size and the area of exposure. Collimated dental x-ray beams have a diameter of 2 3/4 inches. The hard and soft tissues absorb approximately 90% of the x-ray beams directed at patients, while 10% pass through them and reach the film (dental x-ray machine).
Protecting the Operator
Although dental professionals receive less exposure to ionizing radiation than do other occupationally-exposed healthcare workers, operator protection measures are essential to minimize exposure. Personal dosimeters, occupational radiation exposure limits and barrier shielding are all protective measures.
SHIELDING: Radiographic equipment operators should use barrier protection whenever possible. Barriers should contain a leaded window so that the operator can view the patient while they are exposed. If shielding is not possible the operator should be at least 2 meters away from the tube head, and out of direct beam path.
EXPOSURE LIMITS AND PERSONAL DOSMITERS – The annual maximum dose of ionizing radiation allowed for health care workers in the United States is 50 millisieverts (mSv). The lifetime maximum dose is 10mSv multiplied with a person’s years of age. Workers who are likely to be exposed to more than one mSv per year must use personal dosimeters to monitor their exposure. Personal dosimeters must be used by pregnant dental staff who use x-ray equipment, regardless of the expected exposure (Radiation Protection).