Computer-assisted medical instrumentation has recently become more common. For accuracy and precision, the computer and interfacing circuit with the associated digital signal processing algorithm can be used for the evaluation of biological signal. The measurement system based on this structure has a very high degree of efficiency and flexibility because different algorithms can be used. In addition, the system can employ some newly developed software packages. This paper will submit a procedure for computer-assisted medical instrumentation, and also will show a specific application on blood flow.