Algorithm for the determination of projected urethral lumen cross-sections and shape functions.

A method used to obtain computer graphic representations of projected urethral lumen cross-sections is described. The cross-sectional area of the lumen is measured accurately at all stages of voiding. Two methods of background subtraction are considered, direct subtraction from nonvoiding x-rays and subtraction from a least squares regression line. The projected cross-sections are described by simple shape functions. These shape descriptors increase the technique's potential application by providing a quantitative measure of the projected cross-sections.