| 摘要 |
PURPOSE: To extract bloodstream information from a clutter and to give better S/N, by utilizing a speed sample elimination system to realize speed dependency elimination selection using a clutter eliminating filter and a speed determining system and the combination of both. CONSTITUTION: This system utilizes a phased array ultrasonic converter 12, a scanner unit 14, and process display unit 16. An intermediate frequency filter 22 is used to optimize S/N of a returning echo. A clutter eliminating filter 28 is used to eliminate unnecessary Doppler signals. A Doppler processing system 32 decodes selected signals and converts clutter-eliminated Doppler frequency information into speed information at each space point of sample volumes. A circulation averager 33 calculates average speed on each point using only good samples. Since the criterion to eliminate a speed value is made as a value depending on the speed, it fits to the clutter elimination filter and S/N can be improved. |
