title: Correction of background noise in direct digital dental radiography.
abstract: OBJECTIVE
  To clarify the source of noise in direct digital intra-oral radiography with RVG-S (Trophy Radiologie, Vincennes, France) and to use these to develop a method for correction of background noise.
  
  
  METHODS
  Sensor temperature, image acquisition time and X-ray dose were independently analysed with the IPLab Spectrum (Signal Analytics, Vienna, VA) software.
  
  
  RESULTS
  The decrease in pixel value due to the dark current was linearly related to the image acquisition time. Although a variation in sensitivity was observed when the sensor was exposed to X-rays, the mean pixel value of the entire image was linearly related to the exposure time. The image showing only the signal due to X-ray dose was derived from the original RVG-S image by correcting for the dark current and the pixel-by-pixel sensitivity variation of the CCD sensor.
  
  
  CONCLUSIONS
  The image formed only by X-ray dose distribution can be derived by correcting for the background noise.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yoshioka
authors.forename: C
authors.initials: C
authors.lastname: Kobayashi
authors.forename: H
authors.initials: H
authors.lastname: Suda
authors.forename: T
authors.initials: T
authors.lastname: Sasaki
mesh_terms: D000465:Algorithms; D016477:Artifacts; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000295:instrumentation; D019252:Radiography, Dental, Digital / Q000295:instrumentation*; D015203:Reproducibility of Results; D013997:Time Factors