![]() ![]() Results The required field of view (mean ± standard deviation) was measured as 107 ± 7.6 mm anteroposteriorly and 90.3 ± 9.6 mm superoinferiorly. The phantom head was registered to 3 surgical navigation systems (Brainlab, Stryker, and Medtronic) using scans from each system. A phantom head was manufactured by 3-dimensional printing and imaged using 3 CBCT scanners (Carestream, J Morita, and NewTom), a conventional MDCT scanner (Siemens), and highly accurate laser scanner (FARO). Methods The required field of view was measured from the tip of the nose to the posterior clinoid process anteroposteriorly and the nasolabial angle to the roof of the frontal sinus superoinferiorly on 50 consecutive MDCT scans (male = 25 age = 17–85 years). Objective To investigate CBCT as a low-radiation imaging modality for use in surgical navigation. Surgical navigation systems are increasingly being used in endoscopic sinus and skull base surgery, reducing perioperative morbidity. 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.īackground Cone-beam computed tomography (CBCT) is a fast imaging technique with a substantially lower radiation dosage than conventional multidetector computed tomography (MDCT) for sinus imaging. The presence of ring artifact means that CBCT device has lost its calibration. 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.Ĭonclusions: reduction of aliasing artifact is related with the improvement of detectors quality. 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). 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. In these articles only 4 annotated figures were freely accessible in medical publications from PubMed. Results: Only 3 articles out of 434 publications were retained after application of inclusion/exclusion criteria. We limited our search to English and French language. There was no time limit for the search of articles. ![]() The exclusion criteria were: experimental studies, animal studies, studies not related to dentomaxillofacial area, and articles with closed access. ![]() Material and methods: One observer applied five search equations using database PubMed. 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. It's difficult to see beam hardening in a sentence.( Very'soft'x-rays won't ever penetrate the patient to contribute to the image they would get absorbed in the first few millimeters of skin. ) This effect is important in diagnostic x-ray machines, which are designed to filter out very low-energy x-rays before they leave the instrument. ( The total beam energy coming out is lower than the energy coming in, but what's left over is more penetrating. Lower energy radiation is more likely to be scattered or absorbed, so the resulting beam tends to contain gamma ray photons of higher energy ( this effect is called beam hardening ).particles with a lot of energy and particles with little energy. ![]() "' Beam Hardening "': X-ray radiation consists of hard and soft particles, i.One of the features of this family of scanners was the elimination of the " water bag " that EMI used through the use of a beam hardening correction to produce a uniform field.Numerous factors contribute to these streaks : undersampling, photon starvation, motion, beam hardening, and Compton scatter.Beam hardening : This can give a " cupped appearance " when grayscale is visualized as height.In case of a polychromatic beam, the HF is less than one because of beam hardening. ![]()
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