Synthetic aperture ultrasound imaging system

A method of mapping inhomogeneities in tissue comprising the steps of:

• transmitting acoustic energy into said tissue form a first plurality of locations;
• receiving reflections of said acoustic energy at a second plurality of locations;
• and
• reconstructing a wavefield representation with a common depth point velocity analysis of the reflections of said acoustic energy to generate a three-dimensional mapping of said inhomogeneities in tissue.

A method of diagnosing anomalies in human tissue comprising the steps of:

• transmitting acoustic energy into human tissue form a plurality of locations;
• receiving reflections of said acoustic energy at a plurality of locations;
• and
• reconstructing a three-dimensional mapping of the velocity of the acoustic energy in said tissue with a common depth point velocity analysis of the reflections of said acoustic energy;
• and
• comparing the velocity in said tissue with the velocity of known anomalies in human tissue.

A method of imaging an organism comprising the steps of:

• transmitting acoustic energy into a selected portion of the organism from a first plurality of locations;
• receiving reflections of said acoustic energy at a second plurality of locations;
• reconstructing a mapping of the velocity of the acoustic energy in said selected portion with a common depth point velocity analysis of the reflections of said acoustic energy;
• utilizing the velocity mapping to obtain a focus volume of said portion of the organism;
• and
• migrating a plurality of the velocity values from said mapping to obtain a representation of said portion of the organism.

A method of imaging an organism, said method comprising the steps of:

• transmitting acoustic energy from a first transmitter located proximal to said organism;
• receiving reflections of said acoustic energy at a plurality of receivers located proximal to said transmitter, said reflections returning from a selected portion of said organism;
• sampling said received reflections at a fixed sample rate to obtain a first set of time history recordings of the signals reflected from said selected portion, each of said time history recordings originating from a different receiver location proximal to the transmitter;
• repeating said transmitting, receiving and sampling steps for a plurality of transmitter locations proximal to said organism to obtain a first plurality of time history recording sets;
• selecting a group of time history recordings from said first set and said first plurality of time history recording sets, each of the time history recordings in said group associated with a different receiver and transmitter pair, said receiver and transmitter pairs being disposed substantially symmetrically about a common surface point;
• repeating said step of selecting a group for each of a plurality of common surface points;
• determining a set of velocity values associated with each of said common surface points, said set of velocity values obtained from said group of time history recordings, said velocity values representing a three-dimensional field indicative of the actual velocity of the acoustic energy within the selected portion of said organism;
• and
• generating an image utilizing said three
• dimensional field of velocity values.

A method of imaging an organism, said method comprising the steps of:

• transmitting acoustic energy from a first transmitter located proximal to said organism;
• receiving reflections of said acoustic energy from a plurality of receivers located proximal to said transmitter, said reflections returning from a selected portion of said organism;
• sampling said received reflections to obtain a first set of time history recordings of the signals reflected from said selected portion, each of said time history recordings originating from a different receiver location proximal to said transmitter;
• repeating said transmitting, receiving and sampling steps for a plurality of transmitter locations proximal to said organism to obtain a first plurality of time history recording sets;
• selecting a group of time history recordings from said first set and said first plurality of time history recording sets, each of the time history recordings in said group associated with a different receiver and transmitter pair, said receiver and transmitter pairs disposed substantially symmetrically about a common surface point;
• repeating said step of selecting a group for a plurality of common surface points;
• determining a set of velocity values associated with said common surface points, said set of velocity values obtained from said group of time history recordings, said velocity values representing a three-dimensional field indicative of the actual velocity of the acoustic energy within the selected portion of said organism;
• selecting a two-dimensional slice across said three-dimensional field of velocity values;
• and
• displaying said two-dimensional slice.

A method of imaging an organism, said method comprising the steps of:

• transmitting acoustic energy from a first transmitter located proximal to said organism;
• receiving reflections of said acoustic energy from a plurality of receivers located proximal to said first transmitter, said reflections returning from a selected portion of said organism;
• sampling said received reflections at a fixed sample rate to obtain a first set of time history recordings of the signals reflected from said selected portion, each of said time history recordings originating from a different receiver location proximal to the transmitter;
• repeating said transmitting, receiving and sampling steps for a plurality of transmitter locations proximal to said organism to obtain a plurality of time history recording sets;
• selecting a group of time history recordings from said first set and said plurality of time history recording sets, each of the time history recordings in said group associated with a different receiver and transmitter pair, said receiver and transmitter pairs being disposed substantially symmetrically about a common surface point;
• repeating said step of selecting a group for a plurality of common surface points;
• determining a set of velocity values associated with said common surface points, said set of velocity values obtained from said group of time history recordings, said velocity values representing a three-dimensional field indicative of the velocity of the acoustic energy within the selected portion of said organism;
• combining a plurality of said velocity values to obtain a focus volume of said portion of the organism;
• migrating said plurality of velocity values to obtain a three-dimensional image of said portion of the organism;
• and
• displaying a representation of at least a portion of said image.

A method of imaging an organism, said method comprising the steps of:

• a. transmitting a burst of acoustic energy from a transmitter located proximal to said organism, said burst being of sufficient energy to propagate from said transmitter to a selected portion of said tissue and to reflect acoustic signals back to a at least one receiver located proximal to said transmitter;
• b. sampling the acoustic signals reflected back at a fixed sample rate to obtain a time history recording from said at least one receiver;
• c. repeating steps a and b for a plurality of receivers proximal to said transmitter to obtain a first set of time history traces associated with said transmitter;
• d. repeating steps a through c for a plurality of transmitter locations proximal to said organism to obtain a first plurality of sets of time history traces, each of the sets within said first plurality associated with a different transmitter location;
• e. selecting from said first set and said first plurality of sets, a selected plurality of time history traces, each trace in said selected plurality of traces associated with a different transmitter and receiver pair, the transmitter and receiver pairs disposed symmetrically about a common point between the receiver and the transmitter in said pairs;
• f. repeating step e for a plurality of common points having transmitter and receiver pairs disposed symmetrically about said common points;
• g. assembling a set of velocity values associated with the common surface points, said set of velocity values obtained from said selected plurality of time history traces, said velocity values organized to represent a three-dimensional field indicative of the velocity of the acoustic energy within the selected portion of the organism;
• and
• h. generating a two-dimensional image utilizing said three-dimensional field of velocity values.

A signal receiving system for use in an acoustical imaging system, said signal receiving system comprising:

• an array having a plurality of transducer elements capable of functioning as receivers, said array divided into predetermined sampling sets of transducers;
• a set of receiver channels which number fewer than the number of transducers in the array, wherein each receiver channel in said set of receiver channels is assigned to a selected portion of the plurality of transducers in the array, and wherein for any predetermined sampling set of transducers symmetrically located about a selected transducer, said predetermined sampling set of transducers equal in number to the set of receiver channels, each receiver channel in said set of receiver channels is only assigned to one transducer in said predetermined sampling set;
• and
• a switching unit which selectively connects the transducers to the assigned receiver channels for any predetermined sampling set.

A method of switching signals from a selected sampling set of transducers in an acoustical imaging system, wherein the transducers form an array, to a set of receiver channels which are equal in number to the number of transducers in the selected sampling set of transducers, said method comprising the steps of:

• assigning each of the transducers in the array to a respective receiver channel in said set of receiver channels, wherein for any predetermined sampling set of transducers symmetrically located about a selected transducer anywhere within the array, each receiver channel in said set of receivers is assigned to no more than one transducer in said predetermined sampling set;
• selecting a first predetermined sampling set of transducers equal in number to the number of receivers in said set of receiver channels, said first predetermined sampling set symmetric about a selected transducer;
• electrically connecting said first predetermined sampling set of transducers to said set of receiver channels with a switching circuit;
• selecting a second predetermined sampling set of transducers equal in number to the number of receivers in said set of receiver channels, wherein said second predetermined sampling set of transducers comprises a portion of the same transducers in said first predetermined sampling set;
• electrically disconnecting said first predetermined sampling set of transducers from said set of receiver channels with said switching circuit;
• and
• electrically connecting said second predetermined sampling set of transducers to said set of receiver channels with said switching circuit.

A signal receiving system for use in an acoustical imaging system, said signal receiving system comprising:

• an array having a plurality of transducer elements capable of functioning as both transmitters and receivers;
• a set of receiver channels which number less than the number of transducers in the array, wherein each receiver channel in said set is assigned to a selected portion of the plurality of transducers in the array, and wherein for any predetermined sampling set of transducers symmetrically located about a selected transducer, said predetermined sampling set of transducers equal in number to the set of receiver channels, each receiver channel in said set of receiver channels is only assigned to one transducer in said predetermined sampling set;
• and
• a switching unit which selectively connects the transducers to the assigned receiver channels for any predetermined sampling set.