An ultrasound scanner for scanning a medium for anomalies scattering acoustic waves, having ultrasonic transducing means positioned within scanning range of the medium; ultrasonic transmitting means coupled to the transducing means for providing a train of pulsed ultrasonic carrier signals. Each pulsed carrier signal of the train has a constant and unique frequency, the train of pulsed carrier signals together covering a range of frequencies. The transducing means is oriented to propagate the train along a path through the medium. The device further includes (a) means for repeatedly repositioning the transducing means for propagating further trains along a plurality of different paths through the medium, the plurality of different paths together defining a planar cross-section; (b) means coupled to the transducing means and responsive to the steady state phase and amplitude of the received signal to thereby define the total scatter characteristic within the planar cross-section; (c) means for calculating from the characteristic plurality of point characteristics of the acoustic property corresponding to the scatter characteristic; and (d) means for comparing each of the point characteristics with respect to one another for the anomalies.
In an exemplary embodiment partial images of an object are obtained by scanning the object from different directions, e.g. by compound scanning. For a given object region or point, the different partial images may include a response maximum signifying a directionally reflecting region. Other object regions may provide echo signal amplitudes in a range signifying a locally isotropic scattering. According to the disclosure, the partial images are linked or combined taking account of the nature of the respective object regions as being directionally reflecting or nondirectionally scattering.
In an exemplary embodiment, the processing techniques of computerized x-ray tomography are applied to improve resolution transverse to the depth direction, for example with the use of compound ultrasonic scanning. In this way, an improved preliminary image for representing non-directionally scattering image points is attained. The ultrasonic echo signals are also processed to provide a preliminary image based predominantly or exclusively on directionally reflecting image points. The respective preliminary images for each image point or point region are then suitably combined to provide a stored ultrasonic image capable of display of the scanned region of improved accuracy, resolution, and freedom from noise.
A system for the model-based compression of speckle images in which the pulse characteristics of the known coherent imaging system which generated the speckle image to be compressed are used together with a scatterer image model to modify that scatterer image to contain impulse information such that when the impulse information is convolved with the pulse, the speckle image is reproduced. The modified scatterer image is compressed and outputted together with the pulse characteristics so that the speckle image can be reproduced.
An ultrasonic diagnostic apparatus detects variations of an acoustic characteristic to obtain the fluctuation of temperature within a body to be examined. The ultrasonic diagnostic apparatus includes an ultrasonic transducer for transmitting an ultrasonic wave and receiving the reflected ultrasonic wave which is in turn converted into an electric signal. The signal is phase-detected in accordance with a plurality of gate intervals or a plurality of window interval to detect a phase difference therebetween. The relative variation of velocity dispersion before and after heating of the body is obtained on the basis of the phase variation resulting from the variation of the ultrasonic drive frequency.
The invention involves an ultrasonic tomography device having an ultrasonic transmitting and receiving system for scanning an object under examination from different angles line by line, a fluid tank for immersing the object to be examined, a cover for the fluid tank with a round opening in the center for inserting the object under examination, and a support for an ultrasonic transmitting and receiving system which rotates in the fluid tank around an essentially vertical axis aligned toward the round opening in the center of the cover. In the case of such ultrasonic tomography devices, there is both the requirement of obtaining information from areas as close to the chest wall as possible, and the necessity of distinguishing localized information that can be traced back to artifacts, from real localized information. For this purpose, the invention provides an additional horizontal axis, intersecting the vertical axis just a few millimeters below the surface of the fluid, which is attached to a second angled support rotating around a vertical axis. From this additional horizontal axis is suspended a revolving, essentially L-shaped support bearing a second ultrasonic transmitting and receiving system on its free end that is capable of revolving through the median perpendicular to the central opening in the cover, and whose direction of radiation is aligned to the mid-point of the central opening in the cover. An ultrasonic tomography device designed in accordance with the invention is particularly suited for use in medical technology.
