Artifacts related to cone beam computed tomography technology (CBCT) and their significance for clinicians: illustrated review of medical literature.

Abstract

Objective: to explain the meaning and to illustrate technical artifacts (aliasing as well as the ring artifact) and beam hardening (metal artifact) that can be present in the dentomaxillofacial cone beam computed tomography (CBCT), and to check the accessibility of free illustrations of these artifacts in medical publications.
 Material and methods: One observer applied five search equations using database PubMed. The exclusion criteria were: experimental studies, animal studies, studies not related to dentomaxillofacial area, and articles with closed access. There was no time limit for the search of articles. We limited our search to English and French language.
 Results: Only 3 articles out of 434 publications were retained after application of inclusion/exclusion criteria. In these articles only 4 annotated figures were freely accessible in medical publications from PubMed.
 In this paper we presented examples of aliasing, ring artifact, and beam artifacts from I-CAT, Carestream 9000 3D (Kodak), and Planmeca Promax 3D Mid CBCT. The intensity of beam hardening artifact varies from major degradation of image (i.e., subperiosteal implants, bridges, crowns, dental implants, and orthodontic fix appliances), through mean degradation (screws securing titanium mesh, head of mini-implant) to no beam hardening on metallic devices (orthodontic anchorage, orthodontic contention wire) or on dense objects (endodontic treatments, impression materials, Lego box). Some beam hardening artifacts arising from nasal piercing, hairs, or hearing aid device may be present on the image but they will not disturb the evaluation of the field of view.
 Conclusions: reduction of aliasing artifact is related with the improvement of detectors quality. The presence of ring artifact means that CBCT device has lost its calibration. The field of view (FOV) needs to be reduce in order to avoid scanning regions susceptible to beam hardening (e.g., metallic restorations, dental implants). Finally, the accessibility to open knowledge on technique -related CBCT artifacts seems extremely limited when searching at PubMed database.