A method for performing retrospective dynamic transmit focusing beamforming for ultrasound signals, the method comprising the steps of: a) transmitting a plurality of transmit beams from an array transducer, each transmit beam being centered at a different position along the array and each transmit beam having a width or an aperture encompassing a plurality of laterally spaced line positions, each transmit beam width or aperture overlapping at least partially at least the width or the aperture of the immediately adjacent transmit beam or of more laterally spaced transmit beams; b) receiving echo signals with the array transducer; c) processing the echo signals received in response to one transmit beam to produce a plurality of receive lines of echo signals at the laterally spaced line positions within the width or the aperture of the transmit beam; d) repeating the receiving step b) and the processing step c) for the additional transmit beams of the plurality of transmitted transmit beams of step a); e) equalizing the phase shift variance among receive lines at a common line position resulting from transmit beams of different transmit beam positions; f) combining echo signals of receive lines from different transmit beams which are spatially related to a common line position to produce image data; and g) producing an image using the image data; and in which the step e) of equalizing the phase 5 shift is carried out contemporaneously with the processing step c) and d); wherein for each transmission of a transmit beam with a certain aperture, the received echoes are processed by a set of beamformer processors (410a - 410k), each one related to a different line of sight, with each beamformer having a set of dynamic delays and optionally having a set of apodization weights, which are different for each beamformer; said delays are given by the sum of focalisation delays and retrospective transmit beamforming delays, which are the phase shifts between the wave fronts of the different transmit beams centered at different transmission lines at the focal points along one receive line having a certain line location. a) transmitting a plurality of transmit beams from an array transducer, each transmit beam being centered at a different position along the array and each transmit beam having a width or an aperture encompassing a plurality of laterally spaced line positions, each transmit beam width or aperture overlapping at least partially at least the width or the aperture of the immediately adjacent transmit beam or of more laterally spaced transmit beams; b) receiving echo signals with the array transducer; c) processing the echo signals received in response to one transmit beam to produce a plurality of receive lines of echo signals at the laterally spaced line positions within the width or the aperture of the transmit beam; d) repeating the receiving step b) and the processing step c) for the additional transmit beams of the plurality of transmitted transmit beams of step a); e) equalizing the phase shift variance among receive lines at a common line position resulting from transmit beams of different transmit beam positions; f) combining echo signals of receive lines from different transmit beams which are spatially related to a common line position to produce image data; and g) producing an image using the image data; and in which the step e) of equalizing the phase 5 shift is carried out contemporaneously with the processing step c) and d); wherein for each transmission of a transmit beam with a certain aperture, the received echoes are processed by a set of beamformer processors (410a - 410k), each one related to a different line of sight, with each beamformer having a set of dynamic delays and optionally having a set of apodization weights, which are different for each beamformer; said delays are given by the sum of focalisation delays and retrospective transmit beamforming delays, which are the phase shifts between the wave fronts of the different transmit beams centered at different transmission lines at the focal points along one receive line having a certain line location.