Dedicated versus hybrid cone-beam CT: Two options emerge

By Allan Farman, BDS, MBA, PhD, DSc

October 9, 2008 -- Editor's note: Allan Farman's column, Talking Pictures, appears regularly on the advice and opinion page, Second Opinion.

X-ray imaging in dentistry is rapidly moving toward 3D, and it is time for general dentists to take note.

The first FDA-approved cone-beam CT (CBCT) system was in the year 2000, but since that time many competitors have entered the marketplace. The early units included the full maxillofacial field-of-view (FOV) NewTom (QR, Verona, Italy) that in appearance was superficially very much like a medical helical CT unit, and the small (4 x 4-cm) FOV Accuitomo 3D (J. Morita, Kyoto, Japan). The first hybrid system combining traditional digital panoramic radiology with CBCT was the Planmeca Oy ProMax 3D (Helsinki, Finland), which combines a medium-sized FOV from one detector with a second detector for panoramic imaging.

At the International Dental Show (IDS) 2007 in Cologne, Germany, more hybrid systems were released: the E-Woo (Vatech, Korea) Picasso Trio, the Soredex Scanora 3D (Helsinki, Finland), and the Veraviewepocs 3D (J. Morita). This division of choice was increased by the introduction of the Kodak Dental Imaging 9000 at the French Dental Association in 2007.

At the FDI congress in Stockholm, Sweden, in September, this dichotomy in CBCT systems became even more apparent. The Accuitomo 3D has become the large FOV offering from J. Morita with a 12 x 17-cm FOV -- and the Veraviewepocs 3D now is the unit with a 4 x 4-cm FOV -- combined with a digital panoramic sensor.

This month, CBCT will once again take centerstage at ADA 2008 in San Antonio. For three and a half days (Wednesday afternoon through Saturday) six different CBCT systems will be demonstrated at the Live Operatory adjacent to the Commercial Exhibit. In addition, the ADA will have a Standards Committee on Dental Informatics booth to demonstrate the importance of interoperability of image file formats for add-on services both in diagnosis and image guidance.

The obvious major reason behind moving toward a hybrid CBCT system with a small detector is reduced price, since the major cost element is the detector. Detector cost is highly dependent on size. The costs of hybrid CBCT units in the U.S. can now be very similar to those previously found for upper-level digital panoramic systems alone -- i.e., less than $100,000.

Such smaller FOV systems can also provide high-resolution images even with volume element (voxel) resolution below one-tenth of a millimeter, while keeping dose relatively low and also keeping the computer processing time short. Further, the images cover the teeth and supporting tissue rather than the complete anatomy of the head and neck. This restriction in FOV might also eliminate tissues that the average dentist feels uncomfortable to interpret. The hybrid systems are targeted at general dentists, endodontists, and those placing small numbers of uncomplicated dental implants.

The future of dental imaging is multidimensional, and this future is becoming ever more affordable. As I noted in a recent article on the use of CBCT for inspecting impacted third molars prior to extraction and viewing posterior maxillary teeth that have been referred for apical surgery, "Now that we have CBCT and can look in three dimensions as opposed to 2D with a panoramic field-of-view, I would choose CBCT whenever there is doubt."

The comments and observations expressed herein do not necessarily reflect the opinions of, nor should they be construed as an endorsement or admonishment of any particular idea, vendor, or organization.

Copyright © 2008


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