Analysis of the reproducibility of the gray values and noise of a direct digital radiography system

Braz Oral Res. 2015:29:S1806-83242015000100259. doi: 10.1590/1807-3107BOR-2015.vol29.0062. Epub 2015 May 26.

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.

Publication types

  • Evaluation Study

MeSH terms

  • Alveolar Process / diagnostic imaging
  • Analysis of Variance
  • Equipment Design
  • Humans
  • Image Processing, Computer-Assisted / methods*
  • Phantoms, Imaging
  • Radiation Dosage
  • Radiography, Dental, Digital / instrumentation*
  • Radiography, Dental, Digital / methods*
  • Reference Values
  • Reproducibility of Results
  • Time Factors