COMMENTARY

What Are the Risks of Dental X-rays?

Sotirios Tetradis, DDS, PhD; Stuart C. White, DDS, PhD

Disclosures

August 10, 2012

In This Article

What Should the Dentist Do?

Dental radiographs provide a very useful tool in the dentist’s diagnostic armamentarium. Although radiograph benefits outweigh radiation risk,[27] a reasonable and prudent dentist should be cognizant of such a risk.[28,29] It is the dentist's responsibility to consider carefully and justify every radiograph[26] and to employ the means and procedures to optimize radiographic imaging to gain maximum diagnostic information with the minimum radiation.[30]

Avoid preset intervals for radiographs. Dental radiographs should not be prescribed at preset intervals for all patients. Rather, a detailed evaluation of the patient's complaints and history, combined with a thorough clinical examination and assessment of susceptibility to dental diseases, should inform the need for radiographs for diagnosis and treatment planning.[30] Radiographs should be justified on an individual basis and should not be used as screening tools on asymptomatic patients, to document a procedure, or for legal protection. If a patient is referred from another practice, recently obtained dental radiographs should be retrieved rather than subjecting the patient to additional radiation exposure.[30]

Choose necessary radiographs carefully. Once a decision has been made that radiographs are necessary for diagnosis and/or treatment planning, the examination should be optimized. Procedures that will expose the patient to as-low-as-reasonably-achievable (ALARA) radiation should be employed.[26] This begins with the dentist selecting the radiographic examinations with the lowest dose options that adequately address the diagnostic needs. As such, select intraoral, bitewing, or panoramic radiographs should be chosen over cone-beam CT (CBCT)[31] or medical CT. Similarly, for orthodontic purposes, conventional cephalometric radiographs should be used over CBCT for assessment of simple dental malocclusion cases.[32]

Minimize radiation exposure. The next step in reducing patient exposure is to use appropriate procedures during the selected examination that will enhance radiation to provide images with maximum diagnostic information, while at the same time minimizing unnecessary exposure. Thyroid collars should be used during intraoral radiography, particularly for patients younger than 20 years old, to protect the radiosensitive thyroid glands.[33,34] Rectangular collimation will reduce patient exposure to less than half of exposure with round collimation. Use of E/F-speed film or digital imaging will further significantly reduce patient exposure compared with D-speed film.[35] However, the ease of image generation by direct digital imaging systems carries the possibility of excessive numbers of radiographs, in an effort to achieve an "ideal" projection.[36] Leaded lap aprons provide minimal if any advantage beyond that provided by thyroid collars, fast film or digital receptors, and rectangular collimation and may be considered optional, unless their use is required by local or state regulations.[37,38]

Similarly, for extraoral radiography, use of fast film/screen combinations or digital options will significantly reduce patient exposure. It should be noted that to gain the advantages of reduced exposure, intraoral or extraoral digital radiograph systems should use the minimum radiation necessary for the generation of a diagnostic image. Any benefits from using a digital system can be negated by an overexposed radiograph that is digitally adjusted to have acceptable brightness and contrast.

If CBCT imaging is deemed necessary, scanning parameters should be selected that provide the necessary 3-dimensional imaging with appropriate resolution, while at the same time limiting unnecessary patient exposure. Choosing the smallest field of view that will cover the area of interest will minimize exposure to other structures of the face. For tasks, such as implant placement, that do not require the highest resolution image that can be achieved by the scanner, selecting a lesser resolution scan option that uses low mA or decreased number of projections will significantly reduce patient exposure.[39]

In conclusion, justification of dental radiograph selection and optimization of exposure parameters with the ALARA principle in mind should be employed for every patient in the dental practice. Guidelines and selection criteria for the appropriate use of dental radiographs have been published by professional societies and can be used to assist the dentist with this process.[30,40]

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