3D Ultrasonic imaging method

Abstract

A probe for electronic volume data acquisition using ultrasound incorporates a plurality of transducer elements arranged in a two dimensional array having an azimuth direction and an elevation direction. The transducer elements have a first element size in the azimuth dimension and a second element size in the elevation dimension. At least one of the first and second element sizes is at least twice a characteristic wavelength of a waveform used to drive the array of transducer elements, where the characteristic wavelength is defined as the wavelength corresponding to a center frequency of the waveform. Image data is generated in a scanning process using a CAC-BF technique in an azimuth dimension and/or an elevation dimension, to form an ultrasound image line, image plane, or image data cube.

1 . A method for generating image data in an ultrasound scanning process, comprising selectively energizing transducer elements in an array of transducer elements and selectively polling said transducer elements to effectively divide said array into a plurality of subapertures transmitting and receiving a plurality of low-resolution ultrasound beams that span a volume to be imaged; and coherently combining beamformed signals from said subapertures to synthesize an aperture larger than any one of said subapertures and focused at each point of said volume. 
   
   
       2 . The method defined in  claim 1  wherein receiving a plurality of low-resolution ultrasound beams includes receiving, from said transducer elements, return signals encoding reflected ultrasound waveforms; collecting said return signals to form range lines; digitizing said return signals; and coarse beamforming the digitized signals. 
   
   
       3 . The method defined in  claim 2  the coherent combining includes subjecting the coarse beamformed digitized signals to a fine beamforming. 
   
   
       4 . The method defined in  claim 3  wherein at least one of said subapertures receives a plurality of said low-resolution ultrasound beams, the fine beamforming including spatially interpolating adjacent beams of said one of said subapertures. 
   
   
       5 . The method defined in  claim 3  wherein the fine beamforming includes temporally interpolating between samples of said coarse beamformed digitized signals. 
   
   
       6 . The method defined in  claim 3  wherein the fine beamforming includes determining range delays for signal samples. 
   
   
       7 . The method defined in  claim 3  wherein the fine beamforming includes scan-converting the range lines to a high-resolution grid of voxels to form a low-resolution subaperture image for each subaperture, and coherently combining the low-resolution subaperture images to synthesize a larger aperture and a final high-resolution image. 
   
   
       8 . The method defined in  claim 3  wherein the coherent combining further includes range filtering the coarse beamformed digitized signals prior to the subjecting of the coarse beamformed digitized signals to the fine beamforming. 
   
   
       9 . The method defined in  claim 1  wherein at least one of said subapertures receives a plurality of said low-resolution ultrasound beams, the coherent combining including spatially interpolating adjacent beams of said one of said subapertures. 
   
   
       10 . The method defined in  claim 1  wherein the coherent combining includes temporally interpolating said beamformed signals. 
   
   
       11 . The method defined in  claim 1  wherein the coherent combining includes determining range delays for said beamformed signals. 
   
   
       12 . The method defined in  claim 1  wherein the selectively energizing and the selective polling of said transducer elements includes energizing and polling said transducer elements so that each subaperture transmits and receives a respective sequence of overlapping phased-array beams each focused at a different angle. 
   
   
       13 . The method defined in  claim 12  wherein said overlapping phased-array beams are spaced so as to cross approximately at respective −3 dB points. 
   
   
       14 . The method defined in  claim 12  wherein said transducer elements have an inter-element spacing, the overlapping beams of any given one of said subapertures subtending a total angle of less than a weighted mathematical reciprocal of said inter-element spacing. 
   
   
       15 . The method defined in  claim 1  wherein each of said subapertures overlaps an adjacent one of said subapertures, the overlap including at least 50% of the transducer elements included in said adjacent one of said subapertures. 
   
   
       16 . The method defined in  claim 1  wherein each of said subapertures overlaps an adjacent one of said subapertures, the overlap including approximately 50% of the transducer elements included in said adjacent one of said subapertures. 
   
   
       17 . The method defined in  claim 1  wherein said array is a two-dimensional array in an image space having a first dimension and a second dimension, said subapertures extending along at least one of said first dimension and said second dimension. 
   
   
       18 . The method defined in  claim 1  wherein the selective energizing of said transducer elements includes energizing transducer elements of only one of said subapertures to generate at least one outgoing waveform. 
   
   
       19 . The method defined in  claim 1  wherein the selective energizing of said transducer elements includes energizing transducer elements of each of said subapertures so that each of said subapertures generates at least one outgoing waveform. 
   
   
       20 . The method defined in  claim 1  wherein the selective energizing of said transducer elements and the selective polling of said transducer elements are such that each of said subapertures transmits and receives a plurality of low-resolution ultrasound beams that span the volume to be imaged. 
   
   
       21 . The method defined in  claim 1  wherein the selective energizing of said transducer elements and the selective polling of said transducer elements are such that each of said subapertures transmits an outgoing waveform while fewer than all of said subapertures receive reflected waveforms. 
   
   
       22 . The method defined in  claim 1  wherein the selective energizing of said transducer elements and the selective polling of said transducer elements are such that fewer than all of aid subapertures transmit an outgoing waveform while all of said subapertures receive reflected waveforms. 
   
   
       23 - 43 . (canceled)