Tuned-aperture computed tomography (TACT). Theory and application for three-dimensional dento-alveolar imaging.

OBJECTIVES To introduce a new method for creating three-dimensional (3-D) radiographic displays based on optical aperture theory known as tuned-aperture computed tomography (TACT). With a number of advantages over conventional plain film and tomographic imaging. METHODS The TACT algorithm and some of its capabilities are explained and published with results of in vitro simulations produced from a well-tested multi-tube tomosynthetic x-ray system. Examples of TACT reconstructions of a tooth with naturally occurring caries which were produced from multiple projections and generated with a new servo-controlled single-tube prototype are illustrated. Current imaging strategies in dentistry and their shortcomings in the detection of dento-alveolar disease are reviewed. Pertinent theoretical aspects of the TACT reconstruction algorithm are described and dental applications discussed in light of these limitations. RESULTS Results of several published in vitro investigations derived from a prototype TACT system are referenced. Sample images of a tooth with naturally occurring caries derived from an even newer system are displayed. All data are consistent with the hypothesis that TACT imaging yields diagnostic performance either comparable, or superior, to that obtainable from conventional control modalities depending on the diagnostic task. Moreover, all investigations cited demonstrated conclusively the obvious theoretical benefits associated with the acquisition of multiple projections in three dimensions. CONCLUSIONS TACT shows promise as a supplement to film-based dental radiography and as a digital alternative to conventional tomographic systems used in dento-alveolar applications.