Various apparatus using ultrasound technology to non-invasively measure the amount of urine in the human bladder are well known. Some examples of such apparatus are shown and described in U.S. Pat. Nos. 4,926,871; 5,235,985; 6,110,111 and 6,406,431, all owned by the assignee of the present invention. With each of those devices, a three-dimensional ultrasonic “field” is produced within which the bladder is captured and imaged. The accurate imaging of the entire bladder, however, requires that the instrument be accurately aimed toward the bladder on the body of a patient when the imaging is initiated.
In one example of a useful aiming method/system, a circle is depicted on an instrument display, which represents the field covered by the ultrasound cone. Typically, the displayed circle will include cross hairs. An outline of the bladder determined by the apparatus is then superimposed in the circle. The operator then moves the instrument around on the body of the user to center the bladder image as much as possible on the cross hairs. At that point, the determination of bladder volume is made from the ultrasound information.
While such a system works, there are some disadvantages. These include the requirement of a graphical LCD (liquid crystal display) on the apparatus, which increases the cost, complexity and power requirements of the apparatus. In addition, there are occasional operator errors or confusion relative to interpreting the image and determining when the image is sufficiently centered for an accurate scan, or which way the instrument must be moved to produce a proper aiming position.
Further, the three-dimensional ultrasound scans used for the aiming image typically require a relatively long time to acquire and display. The updating of the aiming display following adjustment of the position of the apparatus may not be as fast as is desirable in a typical patient setting, and may in addition cause some confusion on the part of the operator as to the actual result of previously moving the transducer.
Accordingly, the systems/methods disclosed herein are designed to overcome or decrease the above disadvantages of current systems.