Amanda P Candemil1, Benjamin Salmon2, Deborah Queiroz Freitas3, Francisco Haiter-Neto3, Matheus Lima Oliveira3. 1. Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, University of Campinas, Piracicaba (São Paulo), Brazil. Electronic address: amandacandemil@hotmail.com. 2. Université de Paris, Orofacial Pathologies, Imaging and Biotherapies EA2496 Lab, Montrouge, France; Dental Medicine Department, AP-HP, Bretonneau Hospital, Paris, France. 3. Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, University of Campinas, Piracicaba (São Paulo), Brazil.
Abstract
OBJECTIVES: To evaluate the distribution of metal artifacts from the exomass in small field-of-view (FOV) cone beam computed tomography (CBCT) scans. STUDY DESIGN: An image phantom was scanned by using 3 CBCT units. Metal objects were positioned in the exomass, and additional CBCT scans were obtained. Mean gray values were obtained from 16 homogeneous areas and the standard deviation was calculated to quantify gray level inhomogeneity according to distinct zones of the FOV: total area and outer, inner, right, left, and mid-zones. The discrepancy between each zone and the total area was calculated to compare different CBCT units. Mean gray, gray level inhomogeneity, and discrepancy values were separately assessed by using analysis of variance (ANOVA) and Tukey's test (α = 0.05). RESULTS: Overall, the mean gray values were significantly lower in the inner zone, and the gray level inhomogeneity values were significantly higher in the inner and mid-zones irrespective of the presence of metal objects in the exomass. The 3 CBCT units presented significantly different discrepancy values in most conditions. CONCLUSIONS: The distribution of metal artifacts from the exomass follows the inherent gray value dispersion of CBCT images, with greater inhomogeneity in the inner zone of the FOV. This is exacerbated when metal objects are in the exomass.
OBJECTIVES: To evaluate the distribution of metal artifacts from the exomass in small field-of-view (FOV) cone beam computed tomography (CBCT) scans. STUDY DESIGN: An image phantom was scanned by using 3 CBCT units. Metal objects were positioned in the exomass, and additional CBCT scans were obtained. Mean gray values were obtained from 16 homogeneous areas and the standard deviation was calculated to quantify gray level inhomogeneity according to distinct zones of the FOV: total area and outer, inner, right, left, and mid-zones. The discrepancy between each zone and the total area was calculated to compare different CBCT units. Mean gray, gray level inhomogeneity, and discrepancy values were separately assessed by using analysis of variance (ANOVA) and Tukey's test (α = 0.05). RESULTS: Overall, the mean gray values were significantly lower in the inner zone, and the gray level inhomogeneity values were significantly higher in the inner and mid-zones irrespective of the presence of metal objects in the exomass. The 3 CBCT units presented significantly different discrepancy values in most conditions. CONCLUSIONS: The distribution of metal artifacts from the exomass follows the inherent gray value dispersion of CBCT images, with greater inhomogeneity in the inner zone of the FOV. This is exacerbated when metal objects are in the exomass.
Authors: Amanda P Candemil; Benjamin Salmon; Karla F Vasconcelos; Anne C Oenning; Reinhilde Jacobs; Deborah Q Freitas; Francisco Haiter-Neto; Francesca Mangione; Matheus L Oliveira Journal: Sci Rep Date: 2021-09-27 Impact factor: 4.379