Self-referral: an ethical concern with respect to multidimensional imaging in dentistry?

Cone Beam Computerized Tomography (CBCT) is an application that has taken dentistry by storm. With CBCT, imaging is accomplished by using a rotating gantry to which an x-ray source and detector are fixed. A divergent pyramidal-or cone-shaped source of x-radiation is directed through the area of interest onto an area x-ray detector. The x-ray source and detector rotate around a fixed fulcrum within the region of interest (ROI). During the exposure sequence hundreds of sequential planar projection images are acquired of the field of view (FOV) in an arc of at least 180 degrees. In this single rotation, CBCT provides precise, essentially immediate and accurate three-dimensional (3D) radiographic images. As CBCT exposure incorporates the entire FOV, only one rotational sequence of the gantry is necessary to acquire enough data for image reconstruction. Three dimensional imaging certainly has advantages in such clinical situations as the planning of dental implant placement where important structures such as the mandibular canal need to be avoided to prevent reduced quality of life due to injury. Perhaps it is also of value in planning the extraction of impacted mandibular third molars to again help avoid damaging the contents of the mandibular canal. Providing sufficient spatial resolution is possible for a given CBCT unit, it has also proven useful in determining the causes of failed endodontic treatment. Situations where medical multislice CT is used for planning orthognathic and other surgery procedures can benefit from the reduced radiation exposure usually the case for CBCT. Like all imaging procedures involving ionizing radiation, there should prescription based upon diagnostic or image-guidance necessity. The jury is still out on the use of CBCT for planning and tracking regular orthodontic procedures. Beam hardening artifact makes the use of CBCT unsuited to use for detection of dental caries in most instances. At last count approximately 3,000 CBCT units had been purchased in the USA, and 800 units in Germany among other countries. These systems currently vary in price from approximately US $90,000 to more than US $300,000. Depending on the number and price charged for each CBCT imaging procedures performed, a rush to achieve return on investment could well lead to unethical over-prescription of procedures. Such over prescription could have impacts both on healthcare costs and also on the radiation exposure load to the patient. As the tissues included in the imaged volume need to be read to maximize the diagnostic yield potential …