| Summary: | Background/purpose: The aim of this study was to compare the physical and psychophysical characteristics of a new generation of the Digora storage phosphor plate (SPP) system [Digora Optime (Soredex, Helsinki, Finland)] with its previous version [Digora fmx (Soredex, Helsinki, Finland)].
Materials and methods: Radiographs of an aluminum test object with a pattern of holes that varied in depth and diameter were exposed to 65 kVp and 10 mA for nine different time settings ranging from a minimum (0.05 seconds) to a maximum (3.2 seconds) using the Digora Optime and Digora fmx SPP systems. For each system, pixel-intensity (the mean gray value) measurements, contrast resolution, and exposure range were determined and compared. In addition, a perceptibility curve test was used to compare the psychophysical properties of the two SPP systems. Repeated-measures of analysis of variance and paired t tests were used to compare the mean gray values and perceptible number of details at each exposure level (P = 0.05). The average measured intraclass correlation coefficient (AMICC) was used to compare inter-rater agreement for the number of perceived details.
Results: The mean gray level output of fmx images was higher, whereas the contrast was lower than Optime images at all exposure levels (P < 0.05). Images obtained with the Optime system achieved the best contrast at a lower exposure than that of the fmx images. Digora Optime operated over a wide range of exposures; however, the fmx showed a narrower dynamic range. The number of details perceived on Optime images was significantly higher than that obtained on the fmx images at all exposure levels (P < 0.05). Agreement among observers in terms of the number of perceived details was excellent, with the AMICC ranging from 0.845–0.889.
Conclusion: Digora Optime achieved the best contrast at a lower exposure and demonstrated a better dose response. In addition, the perceptibility of low-contrast details was significantly higher for Digora Optime at a wide range of exposures.
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