Cone-beam computed tomography and its applications in dental and maxillofacial radiology

Cone-beam computed tomography (CBCT) was first used in dental and maxillofacial radiology (DMFR) at the end of the 1990s. Since then, it has been successfully established as the standard three-dimensional radiographic imaging technique in DMFR, with a wide variety of applications in this field. This manuscript briefly reviews the background information on the technology and summarises available data on effective dose and dose optimisation. In addition, typical clinical applications and indications of the technique in DMFR are presented.

Introduction

The principle of constructing a volume from one scan dates back to the late 1970s, where a “dynamic spatial reconstructor” using multiple X-ray sources and a rotating gantry was used to produce high-resolution images of the beating human heart.¹ Cone-beam computed tomography (CBCT) has medical applications including vascular imaging and radiotherapy planning; however, it was the seminal work of Mozzo et al.² and Arai et al.³ that provided the basis for the introduction of the technique into the dental and maxillofacial radiology today. CBCT of the maxillofacial region was first described in 1998,² and this was quickly followed by a pure small-volume system for dental applications.³ After these initial reports, it took until the late 2000s before a boom in the use of this novel three-dimensional (3D) technique became evident in dental and maxillofacial radiology. Initially driven by the need for cross-sectional imaging in dental implantology,⁴ the technique at that time generally offered a considerably lower radiation dose than multidetector computed tomography (MDCT).^5,6

The term “cone beam” refers to the beam geometry on the early CBCT units. The beam was cone-shaped because round image intensifiers were being used. As these are no longer state of the art and have now been replaced by rectangular or square flat panel detectors, from a geometrical perspective the term is somewhat inaccurate; however, the term CBCT remains the accepted term for this technique today.

The estimated numbers of CBCT units is now considerably higher than MDCT units. In 2007, the estimated number of CBCT units in the USA was 10,335.⁷ The same also applies for other developed countries. For instance, in Germany, it is estimated that there are at least 6,000 dental and maxillofacial CBCT devices being used. In addition, there is now a huge choice of CBCT units available. In 2012, there were over 47 CBCT devices marketed by 20 companies worldwide.⁸ The aim of this article is to provide an overview of dental and maxillofacial CBCT.