Abstract
We design 3D printed lenses that generate acoustic holograms correcting the aberrations of the skull and producing ultrasonic fields with the shape of brain structures. Using experimental techniques on a human skull phantom (HSP), a multiple-point focusing lens is designed to simultaneously focus at both human hippocampi; a beam following an arbitrary curved trajectory, i.e., a self-bending beam; and a holographic plate producing a broad focus that overlaps with the left hippocampus (LH). Skull and LH shapes are obtained from CT-scans and MRI, respectively. Time-reversal (TR) method is used to obtain the magnitude and phase of the back-propagated field at the lens surface. Lens height is obtained assuming each element to vibrate as a Fabry-Pérot resonator. Resulting lenses are 3D printed with SLA techniques. The three studied cases show similar results in simulation and experiment with and without the HSP: for the multi-focal beam, the reconstructed field accurately matches the target foci; for the curved trajectory beam, the holographic lens reconstructs the target acoustic image; for the broad focus beam, results present the same qualitative performance and provide a similar overall covering of the LH. The reported holographic lenses can be used to control the spatial features of ultrasonic beams inside the skull in an unprecedented manner using single-element ultrasonic sources.
BibTeX citation
@inproceedings{camarenaMedami2019,
author = {Francisco Camarena and Sergio Jiménez-Gambín and Noé Jiménez and José María Benlloch},
booktitle = {MEDAMI 2019: VI Mediterranean Thematic Workshop in Advanced Molecular Imaging. Valencia, Spain. 15-17 May},
editor = {Book of abstracts},
isbn = {ISBN: 978-84-87985-30-4},
month = {5},
organization = {Consejo Superior de Investigaciones Científicas},
pages = {3},
publisher = {Instituto de Instrumentación para Imagen Molecular},
series = {Invited},
title = {Ultrasonic Holograms in the Brain},
url = {https://www.i3m.upv.es/medami2019/},
year = {2019}
}