As disclosed herein, a new and improved method and apparatus provides for the ensonification of at least a portion of a body part with acoustic energy pulses; detects the polarity and amplitude of the resultant echo pulse; and displays the detected data in a color television format to result in an improvement in resolution in indicia of tissue character. This improvement is accomplished by a process which simultaneously detects both the amplitude or strength of the echo pulse and the polarity sense of the echo pulse at the peak amplitude for each echo pulse. The improvement utilizes a general property of acoustical pulses to detect polarity and amplitude of the echo pulse. The amplitude and polarity measures of the echo pulse are used to produce intensity (luminance) and color (chrominance) throughout the body part for each individual picture element (pixel) forming the picture. Since multiple echoes and their corresponding polarities might correspond to a single pixel picture element, averaging of the polarity and amplitude information prior to display is required. Suitable averaging of the luminance and chrominance is provided to obtain the best measure of color within the picture element. Multiple lines of echo pulse trains are then stored as image information and displayed as a final image in a standard color television format.
An ultrasound transducer generates a received signal in response to a reflected ultrasound signal. Polarity and phase information of the reflected ultrasound signal can be obtained by time-selectively amplifying the received signal with a specific gain function. The specific gain function is derived from the received signal itself and is independent of the polarity of the received signal.
An acoustic imaging system capable of producing C-mode images or orthoscopic projection images of a three-dimensional volume at significantly increased speeds of operation is described. For each acoustic pulse transmitted by a piezoelectric transducer array an electronic parallel processing system produces several unique image points whose locations in the image correspond to the Cartesian coordinates of the positions of receiving transducers. While range information is not directly displayed, range discrimination can be realized by means of an optional range dependent gain control or an optional color display in which range discrimination occurs through visual discrimination of differing hues.
An array of acoustic transmit/receive transducers is placed near the body to be imaged. Acoustic energy is projected upon the body sequentially from different ones of the transducers, each projection covering the entire scene or field of view which it is desired to image. The electrical signals produced from reflected acoustic energy picked up by different transducers are phase shifted, or time delayed as appropriate, so that those from any particular point within the body will additively combine in amplitude, while signals from other points will not. In so doing, there is preserved not only the information about the amplitude of the combined signal from the transducers, but also any information about phase shifts (or time delays as the case may be) which does not result in complete alignment of the signals from the different transducers. The resulting complex signals are further processed, to vectorially add them. The signals produced by this further vectorial addition are then used for the visual display of the image. The resulting image is as if the energy projected upon the body had been formed into a scanning beam which is continuously focused in range at all points in the field of view.
A method and apparatus for displaying an image which has a wide dynamic range. Low spatial frequency components of the image are extracted from the image signal and are presented as a color overlay which tints an intensity modulated display of local high spatial frequency image components. In a preferred embodiment, the hue of the color overlay is modulated to indicate whether the local background component is greater than or less than an equilibrium value while the saturation is modulated to indicate the absolute value of the deviation.
An acoustic pulse echo imaging system capable of producing an image of a three-dimensional object utilizing a two-dimensional display having perspective capabilities is described. In the system angular relationships of targets at all ranges are maintained for display. The system uses a two-dimensional transducer array of piezoelectric elements; the array is steered to assume transmit and receive orientations in both azimuth and elevation by producing (1) a directed transmit pulse and many similarly directed receive orientations or (2) a non-directed transmit pulse and many directed receive orientations. For each transmit pulse a parallel processing system produces several unique image points whose locations in the image correspond to the tangents of the angles of the receive orientations in the azimuth and elevation planes. The brightness of each image point is the weighted integral of the echo data received along each receive path. As an option, range discrimination capability is provided by means of a range dependent gain control, brightness shading as a function of range or a color display in which data originating from different ranges is displayed in different hues.
