A method for determination of fractal dimensions of sialographic images.

A method for measuring the fractal dimension of radiographic images was devised by the modified pixel dilation (PD) method, and its accuracy was examined by two types of image analyzers: one controlled by a minicomputer and based on the hexagonal array of the pixels, and the other controlled by a personal computer and based on the square array of the pixels. It was shown that the fractal dimensions measured by using the image analyzers for three curves (straight line, Koch curve, and Sierpinski gasket) were deviated by less than 2.1% from the theoretical dimension. The time required for the measurements fell within 10 seconds by the minicomputer-controlled image analyzer, and within 12 minutes by the personal computer-controlled image analyzer, which contrasts to the 30 minutes or more required for measuring fractal dimensions by other available methods. Analysis of the ductal patterns in sialograms by this method indicated that the fractal dimensions were significantly different between normal parotids and parotids with Sjögren syndrome. The modified PD method can be used for measuring the fractal dimension of ductal patterns in sialograms. The measurements may serve as numerical gradings of the progression of disease.