Ryobun Tachita

Scan converter for a sector scan type ultrasound imaging system

A scan converter is disclosed for use in a sector scan type ultrasound imaging system in which ultrasound echo signals return from targets along a plurality of radial scan lines distributed in a sector field with a substantially equal tangential angular increment with respect to a reference line. The scan converter comprises a sampling circuit which samples the echo signals at a speed inversely proportional to the cosine of the angle of deflection of the radial scan lines with respect to the reference line so that the sampled points align themselves in lateral lines perpendicular to the reference line. The sampled echo signals are converted into digital echo data and stored in a random access memory in the direction of its columns. The stored data are retrieved serially in the direction of the rows and fed into an interpolator for making interpolations between the successively retrieved echo data. The interpolation data are read into a line memory in succession with the data retrieved from the RAM during each raster scan interval, and then retrieved at a constant rate from preselected storage locations so that the data on the raster scan lines have approximately equal density. The retrieved data from the line memory are converted in analog signals and displayed on a viewing screen.

Focusing circuit for ultrasound imaging system

A focusing circuit for focusing an array of transducers of an ultrasound imaging system includes a variable delay line comprising a plurality of summing amplifiers and a plurality of variable delay elements provided between successive summing amplifiers. A plurality of switches is provided for respectively connecting the transducers to selected summing amplifiers. The amount of delay of each variable delay element is individually controlled so that the corresponding electrical signals derived from the transducers arrive in phase at the output end of the variable delay line.

Ultrasonic Diagnostic Equipment Using a Transducer with an Acoustic Lens for Scan Angle Magnification

A new ultrasound diagnostic system having a real-time trapezoidal display format has been developed. The system has an electronically scanning transducer composed of a convex curved array with an acoustic lens for scan angle magnification. This combination of array and lens creates a flat footprint with a length of 6.6 cm at the surface of the transducer and an inspection width of 29 cm at a depth of 15 cm from the surface. Clinical evaluation of this scanner has demonstrated its usefulness for diagnosis of the abdomen, in obstetrics and gynecology and for biopsy applications.