title: Comparison of psychophysical properties of two intraoral digital sensors on low-contrast perceptibility.
abstract: OBJECTIVE
  The psychophysical properties of a new complementary metal oxide semi-conductor-based detector, ProSensor(®) (Planmeca Oy, Helsinki, Finland), in terms of dose response function and perceptibility curve test were performed and compared with those of a charged couple device-based sensor, Dixi(®) (Planmeca Oy).
  
  
  METHODS
  Dose response functions at 66 kVp for a Dixi and a ProSensor were determined by means of multiple exposures to a homogeneous X-ray field covering the whole exposure range. The entry dose of each exposure was measured and registered. The mean grey level in each image was plotted as function of the corresponding exposures for both digital systems. Radiographs of a test object containing ten holes of increasing depth were obtained throughout the exposure range of the two digital sensors at 66 kVp. 12 observers were asked to register the number of perceptible holes in each radiograph. Based on the mean value of the observers' evaluation, the perceptibility curves were constructed, and the integral value under the perceptibility curves were compared between two intraoral sensors.
  
  
  RESULTS
  The results based on dose response function showed that the ProSensor was more sensitive than the Dixi sensor. Paired t-test showed that the minimal perceptible low-contrast details were significantly higher for the ProSensor than for the Dixi sensor (p < 0.001). The integrals below the two perceptibility curves were 33.4 and 69.2 for the Dixi and ProSensor, respectively.
  
  
  CONCLUSIONS
  Applying the new ProSensor may be beneficial to patients owing to its reduced radiation dose and increased perception for low-contrast details in dentistry.
authors.affiliation: Oral Facial Diagnostics and Surgery, Department of Dental Medicine, Karolinska Institutet, Huddinge, Sweden.
authors.forename: X-Q
authors.initials: XQ
authors.lastname: Shi
authors.forename: D
authors.initials: D
authors.lastname: Benchimol
authors.forename: K
authors.initials: K
authors.lastname: Näsström
mesh_terms: D006801:Humans; D015588:Observer Variation; D019047:Phantoms, Imaging; D011601:Psychophysics; D011856:Radiographic Image Enhancement; D019252:Radiography, Dental, Digital; D014796:Visual Perception
keywords: CCD; CMOS technique; digital intraoral detector; digital radiography; intraoral radiograph; perception