Claims
- 1. A method of quantitatively imaging a target region for compressibility and density comprising:
(a) surrounding the target region with a plurality of transducers; (b) transmitting an acoustic pulse from one of the transducers to the target region; (c) receiving pulse-derived temporal data at a plurality of the transducers, wherein a transmission location of the acoustic pulse is known relative to the receiving transducers; (d) removing from the received pulse-derived temporal data of each receiving transducer a record of the acoustic pulse directly transmitted thereto, for producing a set of modified pulse-derived temporal data; (e) determining from the set of modified pulse-derived temporal data a preliminary value for each of a compressibility term and a density term for each point of the target region; (f) repeating steps (b) through (e) for different transmission locations encompassing the target region; and (g) averaging the preliminary values of the respective compressibility and density terms obtained from the different transmission locations, to obtain final values thereof for each point of the target region, whereby the final values represent quantitative image maps of the respective compressibility and density terms of the target region.
- 2. The method of claim 1,
wherein the preliminary values c1 and c2 for the compressibility term and the density term, respectively, for each point of the target region are determined using a least mean square solution represented by the equation: 9[c1c2]=1d[∑ri∑wi2-∑riwi∑wiN ∑riwi-∑ri∑wi].
- 3. The method of claim 1,
further comprising deconvolving the received pulse-derived data to improve resolution, wherein the deconvolved result is represented by the equation: 10ri′(t)=IFTf(ri(f)p(f)+σ).
- 4. The method of claim 3,
further comprising zeroing out the negative frequency components of ri(f) prior to performing the inverse Fourier transform, for reducing artifacts and clutter in the quantitative image maps.
- 5. The method of claim 1,
further comprising the step of converting the respective quantitative image maps of the compressibility term c1 and the density term c2 into corresponding quantitative image maps of compressibility κt and density ρt of the target region represented by the equations: 11κt=κ(1+c1),ρt=3+c23-2c2ρ.
- 6. The method of claim 1,
wherein the different transmission locations are selected from the transducer locations by assigning a transmission function to a different one of the transducers for each pulse transmission.
- 7. The method of claim 1,
wherein the different transmission locations are selected by relocating the transmitting transducer for each pulse transmission.
- 8. A quantitative imaging method comprising:
(a) surrounding a target region with a transmitter and a plurality of receivers; (b) transmitting an acoustic pulse from the transmitter to the target region, wherein a transmission location of the transmitter is known relative to the receivers; (c) receiving pulse-derived signals at the receivers; (d) pre-processing the received pulse-derived signals of each receiver to remove therefrom a directly transmitted component of the acoustic pulse; (e) determining from the pre-processed pulse-derived signals a preliminary value for each of a compressibility term and a density term for each point of the target region; (f) relocating the transmitter to a different transmission location relative to the target region and repeating steps (b) through (e) for a plurality of different transmission locations encompassing the target region; and (g) averaging the preliminary values of the respective compressibility and density terms obtained from the different transmission locations, to obtain final values thereof for each point of the target region, whereby the final values represent quantitative image maps of the respective compressibility and density terms of the target region.
- 9. The method of claim 8,
wherein the preliminary values c1 and c2 for the compressibility term and the density term, respectively, for each point of the target region are determined using a least mean square solution represented by the equation: 12[c1c2]=1d[∑ri∑wi2-∑riwi∑wiN∑riwi-∑ri∑wi].
- 10. The method of claim 8,
wherein the preprocessing step includes deconvolving the received pulse-derived data to improve resolution, wherein the deconvolved result is represented by the equation: 13ri′(t)=IFTf(ri(f)p(f)+σ).
- 11. The method of claim 10,
wherein the preprocessing step includes zeroing out the negative frequency components of ri(f) prior to performing the inverse Fourier transform, for reducing artifacts and clutter in the quantitative image maps.
- 12. The method of claim 8,
further comprising the step of converting the respective quantitative image maps of the compressibility term c1 and the density term c2 into corresponding quantitative image maps of compressibility κt and density ρt of the target region represented by the equations: 14κt=κ(1+c1),ρt=3+c23-2c2ρ.
- 13. The method of claim 8,
wherein the plurality of receivers are fixed with respect to the transmitter whereby relocation of the transmitter simultaneously relocates the receivers.
- 14. A quantitative imaging system comprising:
a plurality of transducers positionable to surround a target region at known positions relative to each other, with at least one of the transducers capable of transmitting an acoustic pulse toward the target region and a plurality of the transducers capable of receiving pulse-derived temporal data; a controller operably connected to the plurality of transducers for selecting different transmission locations encompassing the target region to vary the pulse-derived temporal data received at each receiving transducer; a first data processor module for removing from the received pulse-derived temporal data of each receiving transducer a record of the acoustic pulse directly transmitted thereto to produce a set of modified pulse-derived temporal data associated with one of the different transmission locations; a second data processor module for determining from each set of modified pulse-derived temporal data a preliminary value for each of a compressibility term and a density term for each point of the target region; and a third data processor module for averaging the preliminary values of the respective compressibility and density terms obtained from the different transmission locations, to obtain final values thereof for each point of the target region, whereby the final values represent quantitative image maps of the respective compressibility and density terms of the target region.
- 15. The system of claim 14,
wherein the controller is adapted to select the different transmission locations by actuating a transmitting transducer to the different transmission locations.
- 16. The system of claim 14,
wherein the controller is adapted to select the different transmission locations from the transducer locations by assigning a transmission function to a different one of the transducers for each pulse transmission.
- 17. The system of claim 14,
wherein the transducers are each capable of transmitting an acoustic pulse and receiving pulse-derived temporal data.
- 18. The system of claim 14,
wherein the second data processor module is adapted to determine the preliminary values c1 and c2 for the compressibility term and the density term, respectively, for each point of the target region are determined using a least mean square solution represented by the equation: 15[c1c2]=1d[∑ri∑wi2-∑riwi∑wiN∑riwi-∑ri∑wi].
- 19. The system of claim 14,
further comprising a fourth data processor module adapted to deconvolve the received pulse-derived data to improve resolution, according to the equation: 16ri′(t)=IFTf(ri(f)p(f)+σ).
- 20. The system of claim 19,
further comprising a fifth data processor module adapted to zero out the negative frequency components of ri(f) prior to performing the inverse Fourier transform, for reducing artifacts and clutter in the quantitative image maps.
- 21. The system of claim 14,
further comprising a sixth data processor module for converting the respective quantitative image maps of the compressibility term c1 and the density term c2 into corresponding quantitative image maps of compressibility κt and density ρt of the target region represented by the equations: 17κt=κ(1+c1),ρt=3+c23-2c2ρ.
- 22. A quantitative imaging apparatus comprising:
a transmitter for transmitting an acoustic pulse toward a target region; a plurality of receivers for receiving pulse-derived temporal data, wherein the transmitter and the plurality of receivers are positionable to surround the target region at known positions relative to each other; a controller for repositioning the transmitter to different transmission locations relative to the target region to vary the pulse-derived temporal data at each receiver; and a data processor adapted to: remove from the pulse-derived temporal data of each receiver a record of the acoustic pulse directly transmitted thereto to produce a set of modified pulse-derived temporal data associated with one of the different transmission locations; determine from each set of modified pulse-derived temporal data a preliminary value for each of a compressibility term and a density term for each point of the target region; and average the preliminary values of the respective compressibility and density terms obtained from the different transmission locations, to obtain final values thereof for each point of the target region, whereby the final values represent quantitative image maps of the respective compressibility and density terms of the target region.
- 23. The apparatus of claim 22,
wherein the plurality of receivers are fixed with respect to the transmitter, whereby the controller simultaneously relocates the plurality of receivers together with the transmitter.
- 24. A quantitative imaging system comprising:
means for transmitting an acoustic pulse toward a target region from a transmission location; means for receiving pulse-derived signals at various receiving locations surrounding the target region to produce temporal data corresponding to the various receiving locations, wherein the positions of the receiving locations are known relative to the transmitting location; means for changing the transmission location to a plurality of different transmission locations whereby different pulse-derived temporal data may be received at the various receiving locations; first processor means for removing from the pulse-derived temporal data of each receiver a record of the acoustic pulse directly transmitted thereto to produce a set of modified pulse-derived temporal data associated with one of the different transmission locations; second processor means for determining from each set of modified pulse-derived temporal data preliminary values for a compressibility term and a density term for each point on the target region; and third processor means for averaging the preliminary values of the respective compressibility and density terms obtained from the different transmission locations, to obtain final values thereof for each point on the target region, whereby the final values represent quantitative image maps of the respective compressibility and density terms of the target region.
- 25. A quantitative imaging system comprising:
a plurality of transducers forming a target volume therebetween for receiving a target object to be imaged, with at least one of the transducers capable of transmitting an acoustic pulse into the target volume and a plurality of the transducers capable of receiving pulse-derived temporal data; a controller operably connected to the plurality of transducers for selecting different transmission locations encompassing the target volume to vary the pulse-derived temporal data received at each receiving transducer; a first data processor module for removing from the received pulse-derived temporal data of each receiving transducer a record of the acoustic pulse directly transmitted thereto to produce a set of modified pulse-derived temporal data associated with one of the different transmission locations; a second data processor module for determining from each set of modified pulse-derived temporal data a preliminary value for each of a compressibility term and a density term for each point of a target region; and a third data processor module for averaging the preliminary values of the respective compressibility and density terms obtained from the different transmission locations, to obtain final values thereof for each point of the target region, whereby the final values represent quantitative image maps of the respective compressibility and density terms of the target region.
Government Interests
[0001] The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.