2010 年 18 巻 5 号 p. 51-58
In medical ultrasonography, adjustment of Doppler velocity range and velocity offset has been a complex manual process. In this study an automatic adjustment function was developed and optimized. A hybrid control system that recognizes blood flow conditions and makes an optimal response according to each colldition was developed. As a result, the error rate was reduced to less than one third of the rate achieved by conventional methods (from 10% to about 3%). The new method was then optimized by quality engineering techniques. As a result, the tracking capability of the estimated velocity range was improved to a higher value than the target value (process capability 3: within ±25% of the true value). Complex manual operations were automated and estimation accuracy and response reached a level good enough for practical use. In conventional product development, a function is first checked with a prototype and much time is then spent evaluating and adjusting its performance. In this study, the prototype was simulated and evaluated automatically, based on quality engineering. Compared with conventional cut-and-try methods, the time required for optimization of adjustable parameters was shortened and the reliability of product performance was improved.