| 摘要 |
A system for estimating the volume of fluid in the bladder sequentially scans the bladder with ultrasonic beams that section the bladder into a number of transverse planes. The system determines, from the scan lines associated with a given plane, a plurality of points on each of the front and back walls of the bladder. It then fits a curve to the set of front wall points and another curve to the set of back wall points, to determine an outline of the bladder in the plane. The system next calculates the cross sectional area of the bladder in the plane based on the two curves. After determining the area in each of the planes, the system determines the volume of the bladder by summing weighted version of the planar areas. The system includes a transducer that consists of a plurality of piezo-electric elements held in a relatively thin elastomeric pad and/or substrate that is acoustically impedance matched to skin. The elements are spaced and grouped such that the acoustic beams they produce lie on the plurality of planes, with the first and the last planes separated by approximately seventy degrees. The estimated volume may be is compared with a predetermined overflow threshold, to determine if the user should then void. The system may include a timer that controls the times at which the system produces estimates. The time may decrease the time between estimate calculations if the estimated volume exceeds a predetermined percentage of the overflow threshold.
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