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Published August 2023 | Published + Supplemental Material
Journal Article Open

A method for the geometric calibration of ultrasound transducer arrays with arbitrary geometries

Abstract

Geometric calibration of ultrasound transducer arrays is critical to optimizing the performance of photoacoustic computed tomography (PACT) systems. We present a geometric calibration method that is applicable to a wide range of PACT systems. We obtain the speed of sound and point source locations using surrogate methods, which results in a linear problem in the transducer coordinates. We characterize the estimation error, which informs our choice of the point source arrangement. We demonstrate our method in a three-dimensional PACT system and show that our method improves the contrast-to-noise ratio, the size, and the spread of point source reconstructions by (80 ± 19)%, (19 ± 3)%, and (7 ± 1)%, respectively. We reconstruct the images of a healthy human breast before and after calibration and find that the calibrated image reveals vasculatures that were previously invisible. Our work introduces a method for geometric calibration in PACT and paves the way for improving PACT image quality.

Additional Information

© 2023 The Authors. Published by Elsevier Under a Creative Commons license - Attribution 4.0 International (CC BY 4.0) This work was sponsored by the United States National Institutes of Health (NIH) grants R01 NS102213, U01 NS099717, U01 EB029823, R35 CA220436 (Outstanding Investigator Award), and R01 EB028277. Data and code availability. The data that support the findings of this study are provided within the paper and its Supplementary materials. A demo code for the calibration method has been posted online at https://github.com/karteekdhara98/PACT-geometric-calibration. The reconstruction algorithm and data processing methods can be found in the paper. The reconstruction code is not publicly available because it is proprietary and is used in licensed technologies. Declaration of Competing interest. L.V.W. has a financial interest in Microphotoacoustics, Inc., CalPACT, LLC, and Union Photoacoustic Technologies, Ltd., which, however, did not support this work. The other authors declare no competing interests.

Acknowledgement

This work was sponsored by the United States National Institutes of Health (NIH) grants R01 NS102213, U01 NS099717, U01 EB029823, R35 CA220436 (Outstanding Investigator Award), and R01 EB028277.

Funding

This work was sponsored by the United States National Institutes of Health (NIH) grants R01 NS102213, U01NS099717, U01 EB029823, R35 CA220436 (Outstanding Investigator Award), and R01EB028277.

Data Availability

The data that support the findings of this study are provided within the paper and its Supplementary materials. A demo code for the calibration method has been posted online at https://github.com/karteekdhara98/PACT-geometric-calibration. The reconstruction algorithm and data processing methods can be found in the paper. The reconstruction code is not publicly available because it is proprietary and is used in licensed technologies.

Ethics

All human imaging experiments were performed with the relevant guidelines and regulations approved by the Institutional Review Board of the California Institute of Technology (Caltech). The human experiments were performed in a dedicated imaging room. Written informed consent was obtained from all the participants according to the study protocols.

Conflict of Interest

L.V.W. has a financial interest in Microphotoacoustics, Inc., CalPACT, LLC, and Union Photoacoustic Technologies, Ltd., which, however, did not support this work. The other authors declare no competing interests.

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Additional details

Created:
August 22, 2023
Modified:
November 21, 2023