Systems and methods for increasing efficiency of ultrasound waveform tomography
View Patent ↗Ultrasound tomography imaging methods for imaging a tissue medium with one or more ultrasound transducer arrays comprising a plurality of transducers, wherein said transducers comprise source transducers, receiving transducers. The methods include assigning a phase value or time delay to source transducers, exciting the transducers and calculating a search direction based on data relating to the excited transducers.
1. An ultrasound tomography imaging method for imaging a tissue medium utilizing a synthetic-aperture ultrasound tomography system comprising two or more ultrasound transducer arrays, spaced apart from each other, each comprising a plurality of transducers, wherein said transducers comprise source transducers, receiving transducers, or both, the method comprising:
assigning a different phase value to each of at least three source transducers of the plurality of source transducers of the synthetic-aperture ultrasound tomography system;
exciting the at least three source transducers of the two or more ultrasound transducer arrays of the synthetic-aperture ultrasound tomography system in accordance with the assigned different phase values to generate a plurality of ultrasound waveforms in the tissue medium;
receiving data from the receiving transducers in accordance with transmissions and reflections of the plurality of ultrasound waveforms through the tissue medium;
performing a numerical simulation of forward propagation of wavefields from the source transducers and backward propagation of wavefields from the receiving transducers based on the data from the receiving transducers;
calculating a search direction based on the forward propagation of wavefields and the backward propagation of wavefields;
updating a model based on the search direction; and
computing an ultrasound waveform tomography image reconstruction in accordance with the updated model.
2. A method as recited in claim 1 , wherein the phase value is randomly assigned.
3. A method as recited in claim 2 , wherein said phase value functions as a source signature between different ones of the source transducers.
4. A method as recited in claim 2 , wherein said phase value reduces cross interference produced by different ones of the source transducers.
5. A method as recited in claim 1 , further comprising:
performing numerical waveform inversion to generate the ultrasound waveform tomography image reconstruction;
wherein said phase values are assigned during the numerical waveform inversion.
6. A method as recited in claim 5 , wherein the image reconstruction comprises calculating forward wavefield propagation from source transducers and backward wavefield propagation from receiving transducers.
7. A method as recited in claim 6 , wherein the image reconstruction further comprises:
receiving a transmission signal and a reflection signal at one of the receiving transducers within the one or more ultrasound transducer arrays; and
generating an ultrasound waveform tomography image reconstruction using both the acquired reflection and transmission signals.
8. A method as recited in claim 5 , wherein said image reconstruction is a function of:
E
(
m
)
=
min
m
∑
s
=
1
N
s
∫
[
d
s
(
t
)
-
p
s
(
m
,
t
)
]
2
dt
,
where E(m) is the misfit function, d is one of transmission data and reflection data, s is a source index indicating one of the source transducers, N s is the number of source transducers, and m is the model parameter.
9. A method as recited in claim 8 , wherein the data from the receiving transducers comprise either reflection data or transmission data from the transducers.
10. An ultrasound tomography imaging system for imaging a tissue medium comprising:
two or more ultrasound transducer arrays, spaced apart from each other, each of the ultrasound transducer arrays comprising a plurality of transducers, the transducers comprising a plurality of source transducers and a plurality of receiving transducers;
a processor; and
programming executable on said processor and configured for:
assigning a different phase value to each of at least three source transducers of the plurality of source transducers;
exciting the at least three source transducers of the two or more ultrasound transducer arrays in accordance with the assigned different phase values to generate a plurality of ultrasound waveforms in the tissue medium;
receiving data from the receiving transducers in accordance with transmissions and reflections of the plurality of ultrasound waveforms through the tissue medium;
performing a numerical simulation of forward propagation of wavefields from the source transducers and backward propagation of wavefields from the receiving transducers based on the data from the receiving transducers;
calculating a search direction based on the forward propagation of wavefields and the backward propagation of wavefields;
updating a model based on the search direction; and
computing an ultrasound waveform tomography image reconstruction in accordance with the updated model.
11. A system as recited in claim 10 , wherein the phase value is randomly assigned.
12. A system as recited in claim 11 , phase value functions a source signature between different ones of the source transducers.
13. A system as recited in claim 11 , wherein said phase value reduces cross interference produced by different ones of the source transducers.
14. A system as recited in claim 11 :
wherein said programming is further configured for performing numerical waveform inversion to generate the ultrasound waveform tomography image reconstruction;
wherein said phase values are assigned during the numerical waveform inversion.
15. A system as recited in claim 14 , wherein the image reconstruction comprises calculating forward wavefield propagation from source transducers and backward wavefield propagation from receiving transducers.
16. A system as recited in claim 14 , wherein the image reconstruction further comprises:
receiving a transmission signal and a reflection signal at one of the receiving transducers within the one or more ultrasound transducer arrays; and
generating an ultrasound waveform tomography image reconstruction using both the acquired reflection and transmission signals.
17. A system as recited in claim 14 , wherein said image reconstruction is a function of:
E
(
m
)
=
min
m
∑
s
=
1
N
s
∫
[
d
s
(
t
)
-
p
s
(
m
,
t
)
]
2
dt
,
where E(m) is the misfit function, d is one of transmission data and reflection data, s is a source index indicating one of the source transducers, N s is the number of source transducers, and m is the model parameter.
18. A system as recited in claim 17 , wherein the data from the receiving transducers comprise either reflection data or transmission data from the transducers.