Transmissive imaging and related apparatus and methods
Apparatus and methods are described that include ultrasound imaging devices, which may operate in a transmissive ultrasound imaging modality, and which may be used to detect properties of interest of a subject such as index of refraction, density and/or speed of sound. Devices suitable for performing high intensity focused ultrasound (HIFU), as well as HIFU and ultrasound imaging, are also described.
1. A method, comprising:
accessing a plurality of measurements of a subject, the plurality of measurements resulting at least in part from detection of ultrasound radiation by an ultrasound imaging device, the ultrasound imaging device comprising a plurality of ultrasound sources including a first ultrasound source and a plurality of ultrasound sensors including a first ultrasound sensor;
calculating, using at least one processor, a first image of the subject from the plurality of measurements by using first path length information for a straight path between the first ultrasound source and the first ultrasound sensor;
calculating, using the at least one processor, second path length information at least in part by computing at least one refractive path between the first ultrasound source and the first ultrasound sensor using the first image; and
calculating, using the at least one processor, a second image of the subject from the plurality of measurements by using the second path length information,
wherein said calculating the first image of the subject comprises calculating the first image by using a compressive sensing image reconstruction technique,
wherein said calculating the second image of the subject comprises calculating the second image by using the compressive sensing image reconstruction technique, and
wherein using the compressive sensing image reconstruction technique to calculate the first image of the subject comprises identifying a solution to a first system of linear equations relating the plurality of measurements to a property of the subject, wherein the first system of linear equations was obtained based at least in part on the first path length information.
2. The method of claim 1 , wherein said calculating the second path length information comprises computing the at least one refractive path using Fermat's principle.
3. The method of claim 2 , wherein said calculating the second path length information further comprises obtaining a solution to a differential equation.
4. The method of claim 1 , wherein using the compressive sensing image reconstruction technique to calculate the second image of the subject comprises identifying a solution to a second system of linear equations relating the plurality of measurements to the property of the subject, wherein the second system of linear equations was obtained based at least in part on the second path length information.
5. The method of claim 1 , wherein the first image of the subject is a volumetric image of the subject.
6. The method of claim 1 , wherein the second image of the subject is a volumetric image of the subject.
7. The method of claim 1 , wherein the plurality of measurements was obtained by the ultrasound imaging device operating in a transmissive modality.