Method and apparatus for transmit beamformer system

• US 6,363,033 B1
• Filed: 08/28/2000
• Issued: 03/26/2002
• Est. Priority Date: 08/05/1994
• Status: Expired due to Term

• Current Assignee: Acuson Corporation (Siemens AG)
• Original Assignee: Acuson Corporation (Siemens AG)
• Inventors: Cole, Christopher R., Liu, Thomas, Gee, Albert
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US09/649,813
• Time in Patent Office: 575 Days
• Field of Search: 367/138, 367/7, 367/11, 600/447
• US Class Current: 367/138
• CPC Class Codes: G01S 15/8915 using a transducer array
• CPC Class Codes: G01S 15/8979 Combined Doppler and pulse-echo imaging systems
• CPC Class Codes: G01S 15/8988 Colour Doppler imaging
• CPC Class Codes: G01S 7/52017 particularly adapted to short-range imaging G01S7/53 takes precedence
• CPC Class Codes: G01S 7/52026 Extracting wanted echo signals Doppler systems G01S15/50; Doppler short range imaging systems G01S15/8979
• CPC Class Codes: G01S 7/52028 using digital techniques
• CPC Class Codes: G01S 7/52046 Techniques for image enhancement involving transmitter or receiver image enhancement by image data processing G06T5/00
• CPC Class Codes: G01S 7/52049 using correction of medium-induced phase aberration
• CPC Class Codes: G01S 7/52066 Time-position or time-motion displays
• CPC Class Codes: G01S 7/5209 using multibeam transmission
• CPC Class Codes: G01S 7/52095 using multiline receive beamforming
• CPC Class Codes: G10K 11/341 Circuits therefor
• CPC Class Codes: G10K 11/345 using energy switching from one active element to another

Abstract

A digital transmit beamformer system with multiple beam transmit capability has a plurality of multi-channel transmitters, each channel with a source of sampled, complex-valued initial waveform information representative of the ultimate desired waveform to be applied to one or more corresponding transducer elements for each beam. Each multi-channel transmitter applies beamformation delays and apodization to each channel'"'"'s respective initial waveform information digitally, digitally modulates the information by a carrier frequency, and interpolates the information to the DAC sample rate for conversion to an analog signal and application to the associated transducer element(s). The beamformer transmitters can be programmed per channel and per beam with carrier frequency, delay, apodization and calibration values, For pulsed wave operation, pulse waveform parameters can be specified to the beamformer transmitters on a per firing basis, without degrading the scan frame rate to non-useful diagnostic levels. Waveform parameters can be specified to the transmitters by an external central control system which is responsible for higher level flexibility, such as scan formats, focusing depths and fields of view. The transmit pulse delay specified per-channel to each transmitter is applied in at least two components: a focusing time delay component and a focusing phase component. The carrier frequency can be specified for each transmit beam, to any desired frequency within a substantially continuous predefined range of frequencies, and a beam-interleaved signal processing path permits operation in any of several predefined processing modes, which define different parameter sets in a trade-off among (1) the number of beams produced; (2) per-beam initial waveform sample interval; and (3) transmit frequency.

Claims

1. A method for transmitting ultrasonic waveforms from an ultrasound system, the method comprising the steps of:

(a) generating at least first and second waveforms with substantially digital transmitters, the digital transmitters corresponding to at least two channels and being operable to change waveform parameters at a rate allowing scan line to scan line adjustment and operable to change the waveform parameters independently for each of the at least two channels; and

(b) transmitting at least first and second beams substantially simultaneously, the first and second beams responsive to the first and second waveforms.

2. The method of claim 1 wherein the step (a) comprises:

providing to the first channel initial waveform samples; and

applying to the ultrasonic transducer an output waveform responsive to said initial waveform samples, said method further comprising, prior to said step of applying, at least one of;

the step of modulating by a desired frequency samples in said signal path,

the step of upsampling samples in said signal path,

the step of interpolating samples in said signal path,

the step of time delaying by a time delay samples in said signal path,

the step of focus filtering with a filter samples in said signal path, and the step of phase rotating by a phase samples in said signal path.

3. An ultrasound beamformer apparatus for transmitting ultrasonic waveforms, the apparatus comprising:

first and second digital transmitters corresponding to at least first and second channels, the first and second digital transmitters operable to change waveform parameters at a rate allowing scan line to scan line adjustment and operable to change the waveform parameters independently for each of the at least two channels; and

a transducer comprising first and second transducer elements connected with the first and second channels respectively.

4. The apparatus of claim 3 wherein the first channel includes at least one of the following elements:

an upsampler, an interpolator, a modulator, a time delay element, and a phase rotation element.

5. The apparatus of claim 3 wherein at least one of the first and second digital transmitters comprises:

said first source of initial waveform samples

a digital signal processing path;

a DAC coupled to said digital signal processing path; and

an output signal path coupled to said DAC.

6. Apparatus according to claim 5, wherein said first source of initial waveform samples comprises one of the group consisting of (I)(a) a memory containing said first initial waveform samples, (b) in combination, (1) a memory containing said first initial waveform samples and having data output coupled to said digital signal processing path, said memory further having an address input, and (2) a counter having an output coupled to said address input of said memory, (c) a source of an impulse coupled to a waveshaping filter in said digital signal processing path, and (d) means for computing said first initial waveform samples sequentially and providing the first initial waveform samples sequentially to said digital signal processing path;

and wherein said digital signal processing path includes at least one of the following;

(II)(a) an upsampler, (b) an interpolator, (c) a modulator, (d) a time delay element, (e) a phase rotation element, (f) an apodization multiplier, (g) an encoder which provides to said DAC samples from said digital signal path in encoded form, (h) a filter, and (i) means for time delaying samples in said digital signal path by creating interpolated samples which approximate a desired time delay.