Corrections for wavefront aberrations in ultrasound imaging
OwnerBjorn Angelsen, Tonni Johansen +1inventors
InventorsBjorn Angelsen, Tonni Johansen, Trond Varslot
Life of this patent
Estimating the term…
Abstract
An estimation method for correction filters for wavefront aberration correction in ultrasound imaging is given. The aberration is introduced due to spatial variations of the ultrasound propagation velocity in heterogeneous tissue. The correction filters are found as eigenvectors of the cross-correlation matrix of the element signals. In particular, the eigenvectors with a small spatial linear/plane phase component is sought. Detailed methods for calculating the eigenvectors are given.
Claims25
A method for corrections of wavefront aberrations in ultrasound imaging, using an ultrasound transducer array with a two-dimensional distribution of elements where the surface dimension of the elements is shorter than the correlation length of the wave front aberrations of the received signal across said array surface, and where
- the elements are connected to a transmit and a receive beam former where homogeneous delay and amplitude corrections of the element signals for direction steering and focusing of the transmit and receive beams are done based on the assumption of a constant propagation velocity in the tissue according to known methods, and
- in addition the element signals are in receive mode filtered in receive aberration correction filters before being added to the final, corrected receive beam former output signal, and in transmit mode the element pulses are filtered in transmit correction filters to form the aberration corrected element pulses that are transmitted,
- the correction filter characteristics for each element being estimated for at least one frequency from corresponding components of at least one eigenvector of the correlation matrix of the received element signals at said frequency.
An ultrasound imaging instrument with corrections of wave front aberrations for the transmit and/or the receive beams, comprising
- an ultrasound transducer array with a two-dimensional distribution of elements where the surface dimension of the elements is shorter than the correlation length of the wave front aberrations of the received signal across said array surface, and where
- a transmit and a receive beam former connected to the array elements, and where beam forming is done with homogeneous delay and amplitude corrections of the element signals for direction steering and focusing of the transmit and receive beams, based on the assumption of a constant propagation velocity in the tissue according to known methods, and
- means for aberration correction filtering of said the element signals in addition to said homogeneous delay corrections before in receive mode the aberration corrected element signals are added to the final, corrected receive beam former output signal, and in transmit mode the aberration corrected pulses are transmitted for each element to form said transmit beam,
- means for estimation of the correction filter characteristics for at least one frequency for each element signal as the components of at least one eigenvector of the correlation matrix of the received element signals at said frequency.
Dependencies are inferred from the claim text.