Determine exact optimal parameters of 3D-printed holographic acoustic lenses for transcranial FUS

Determine the exact physical parameter values that define the optimal 3D‑printed holographic acoustic lens for correcting transcranial focused ultrasound aberrations using single‑element transducers, specifically quantifying the polymer p‑wave speed and the resulting lens thickness under a given 3D‑printer voxel size and typical transducer–target configurations, beyond the current trend‑based interval of desirable thicknesses evidenced by simulations and experiments.

Background

The paper evaluates how polymer p‑wave speed and resulting lens thickness influence the performance of 3D‑printed holographic acoustic lenses used to correct skull‑induced aberrations in transcranial focused ultrasound. Through simulations and a validation experiment, the authors identify optimal thickness ranges (in voxels) that appear largely independent of frequency, aperture, and distance, but they do not pin down exact optimal parameter values.

In the discussion, the authors state that a more comprehensive set of simulations (varying wavelength, transducer–target distances, lens apertures) and additional experiments would be needed to achieve a conclusive determination of the precise physical parameters that define the optimal lens. They explicitly acknowledge that, at present, the exact properties of the optimal lens cannot be determined.

References

In order to obtain a conclusive result regarding the precise physical parameters that define the optimum lens, it would be necessary -in addition to more similar experiments to increase the statistical significance of the results- also to increase the number of types of simulations, with more wavelength values, more distances to the focus point (including points beyond the geometric centre of the transducer) or more lens apertures. However, although we cannot determine the exact properties of the optimal lens, the presence of a trend that allows the establishment of an interval of desirable values has been clearly evidenced by the results obtained.

— On the evaluation of the suitability of the materials used to 3D print holographic acoustic lenses to correct transcranial focused ultrasound aberrations  (2401.17818 - Ferri et al., 2024) in Section 5 (Discussion)