title: Analysis of the reproducibility of the gray values and noise of a direct digital radiography system.
abstract: The aim of this study was to evaluate the reproducibility of the gray values and noise of a direct digital radiography system (Visualix eHD) for various exposure times and analyzed regions. To obtain radiographic images in a standardized manner, the digital sensor of the system and a stepwedge were positioned in a phantom at a focus-film distance of 30 cm in a dental device at 70 kV, 7 mA and 2.2 mm filtration. Ten consecutive repetitions of X-ray imaging were performed at each exposure time (0.05, 0.07, 0.09 and 0.13 s). Gray values were analyzed using ImageJ software in five regions of interest (ROIs): alveolar bone (AB), soft tissue (ST) and three steps of the stepwedge (S1, S2 and S3). The results showed that both the variability of the gray values and the noise were statistically greater (p < 0.05) in the most radiolucent region (ST). Only the noise was affected by the exposure time. In conclusion, the reproducibility of the gray values and the noise of the Visualix eHD system can vary in specific areas with different radiolucency.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Universidade Norte do Paraná, Londrina, PR, Brazil.
authors.forename: Marcelo Lupion
authors.initials: ML
authors.lastname: Poleti
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Universidade Norte do Paraná, Londrina, PR, Brazil.
authors.forename: Thais Maria Freire
authors.initials: TM
authors.lastname: Fernandes
authors.affiliation: Department of Stomatology, Faculty of Dentistry, Universidade de Fortaleza, Fortaleza, CE, Brazil.
authors.forename: Renata Cordeiro
authors.initials: RC
authors.lastname: Teixeira
authors.affiliation: Department of Stomatology, Bauru School of Dentistry, Universidade de São Paulo, Bauru, SP, Brazil.
authors.forename: Ana Lúcia Alvares
authors.initials: AL
authors.lastname: Capelozza
authors.affiliation: Department of Stomatology, Bauru School of Dentistry, Universidade de São Paulo, Bauru, SP, Brazil.
authors.forename: Izabel Regina Fischer
authors.initials: IR
authors.lastname: Rubira-Bullen
mesh_terms: D000539:Alveolar Process / Q000000981:diagnostic imaging; D000704:Analysis of Variance; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D019252:Radiography, Dental, Digital / Q000295:instrumentation* / Q000379:methods*; D012016:Reference Values; D015203:Reproducibility of Results; D013997:Time Factors