The video camera compared with the densitometer as a scanning device for microradiography

In the recent past image analysis systems, comprising a video (CCD) camera and dedicated software, have replaced densitometer-based systems to analyze mineral content profiles using transversal microradiography (TMR). The main reasons for the introduction of the CCD camera were the ease and speed at which it can be operated. The densitometer, as a scanning device for TMR, has in the recent years been validated and is in this study considered as 'gold standard'. Comparisons of the two scanning devices for measuring the optical density of microradiograms have never been reported in the literature. The focus of this study was on accuracy and reproducibility of the scanning devices with the emphasis put on possible limitations of the CCD camera relative to the densitometer. These include resolution, number of gray levels and homogeneity of illumination of the scan area. The microscope was arranged in such a way that the same area on the microradiogram could be assessed by both scanning devices. Three different types of lesions were analyzed: a subsurface lesion, a surface-softened lesion and a laminated lesion. Paired t tests showed no significant difference between the mineral content profiles produced by the two scanning devices. The integrated mineral loss values were calculated and compared with analysis of variance and showed no significant differences. It is therefore concluded that mineral content profiles and integrated mineral loss obtained by the CCD camera are as accurate and reproducible as those obtained by the densitometer.