arXiv subjects

Costas D. Arvanitis

Publications and source records attributed to Costas D. Arvanitis.

3 recordsLinked to original sources

arXiv2025

Acoustic Holography in the Megahertz Frequency Range with Optimal Lens Topologies and Nonlinear Acoustic Feedback

Acoustic holography in the megahertz frequency range can impact numerous applications, including manufacturing, non-destructive testing, and transcranial ultrasound. However, designing lens topologies for complex acoustic holograms in the megahertz range poses a significant challenge, as weave propagation effects through the lens cannot be ignored. Here, we show that the inherent ability of heterogeneous angular spectrum approach to incorporate in plane varying speed-of-sound maps and support rapid differentiable optimization of lens thickness profiles can generate lens topologies for high fidelity acoustic holography. Crucially, we show that this framework can also account for wavefront aberrations in the propagation media, providing the opportunity to reconfigure this disruptive technology for high precision neuro-interventions. Our investigations also revealed that low frequency acoustic feedback generated by nonlinear mixing of high frequency waves allows attaining accurate skull-compensating lens alignment and creates the possibility to monitor CSF fluid build-up and removal in hydrocephalus. Together, our findings support the design of simple, economical, and high-performance ultrasound systems.

physics.app-ph↗

arXiv2020

Acoustic Source Localization with the Angular Spectrum Approach in Continuously Stratified Media

The angular spectrum approach (ASA)---a fast, frequency domain method for calculation of the acoustic field---enables passive source localization and modeling forward propagation in homogeneous media with high computational efficiency. Here we show that, if the medium is continuously stratified, a first-order analytical solution may be obtained for the field at arbitrary depth. Our simulations show that the stratified ASA solution enables accurate source localization as compared to the uncorrected ASA (error from 1.2$\pm$0.3 to 0.49$\pm$0.3 wavelengths) at scalings relevant to biomedical ($kL \sim$ 500, where $L$ is the length of the measurement aperture), underwater ($kL \sim$ 800), and atmospheric ($kL \sim$ 10) acoustic applications. Overall the total computation was on the order milliseconds on standard hardware (225$\pm$84 ms, compared with $78\pm63$ ms for the homogeneous ASA formulation over all cases). Collectively, the results suggest the proposed ASA phase correction enables efficient and accurate method for source localization in continuously stratified environments.

eess.SP↗

arXiv2019

Heterogeneous Angular Spectrum Approach for Trans-skull Imaging and Focusing

Ultrasound, alone or in concert with circulating microbubble contrast agents, has emerged as a promising modality for therapy and imaging of brain diseases. While this has become possible due to advancements in aberration correction methods, a range of applications, including adaptive focusing and tracking of the microbubble dynamics through the human skull, may benefit from even more computationally efficient methods to account for skull aberrations. Here, we derive a general method for the angular spectrum approach (ASA) in a heterogeneous medium, based on a numerical marching scheme to approximate the full implicit solution. We then demonstrate its functionality with simulations for (human) skull-related aberration correction and trans-skull passive acoustic mapping. Our simulations show that the general solution provides accurate trans-skull focusing as compared to the uncorrected case for clinically relevant frequencies, apertures, and targets, with the effects of skull attenuation and amplitude shading included. In the case of source localization, our method leads to an average of 75 % error reduction and 40 to 60 % increase in peak intensity, evaluated over the range of frequencies as compared to the homogeneous medium ASA. Overall, total computation times for both focusing and point source localization of the order milliseconds can be attained with this approach. Collectively our findings indicate that the proposed phase correction method based on the ASA could provide a computationally efficient and accurate method for trans-skull transmit focusing and imaging of point scatterers, potentially opening new possibilities for treatment and diagnosis of brain diseases.

eess.SP↗