New methods for the ultrasonic visualization of tissue, achieved by employing a newly developed versatile instrumentation system, are outlined and their application to the examination of brain is illustrated. The complete system, whose operating characteristics are described in detail, incorporates an on-line mediumsized digital computer, implementing omnidirectional scanning, utilizing three translational and two rotational degrees of freedom; relief display, which combines intensity modulation and deflection of the oscillograph beam by the echo signals; and segmental construction of echograms, which incorporates wide dynamic range combined with high resolution via program control of receiver gain as a function of range and echo strength. Omnidirectional scanning permits the more complete viewing of tissue interfaces than is possible with the usual compound-scanning methods. Relief display provides an additional parameter as compared to the common flat format for the presentation of echo information in a two-dimensional picture, and the type of echo signal composition at individual positions on an echogram thus can be represented The relief format also facilitates detection of significant echo signals against the background. Comprehensive presentation eliminates the need for, and problems associated with, time-variable gain in receiver amplification and also provides for much greater flexibility in the choice of an amplifier gain characteristic as a function of signal amplitude. The illustrative results presented demonstrate that new ultrasonic visualization methods can be used to detect and localize (1) internal structural features of the cranial vault, (2) external features of the brain (ventricular, cisternal, and fissural surfaces); and (3) major blood vessels (midsagittal sinuses) in considerable detail, under the condition that acoustic energy does not traverse bone.

A method of observing the sound field in transient radiation from a piston source

No abstract

An impulsive ultrasound wave as membrane radiated from a transmitter, a thick piezoceramic transducer, is used for ultrasonic imaging. The transmitter is fixed and a probe type hydrophone with tiny piezoceramic transducer moves just a few millimeters from the radiation surface. An object is set very close to or put onto the radiator surface. The image is characterized by the amplitude and the transit-time of the penetrating wave through the object. A coded ultrasonic pulse train is also used to make ultrasonic images.

Observation of the sound field in transient radiation from a concave piston source using time-transition pattern