Accurate prediction of transmission through a lensed row-column addressed array

Øygard, Sigrid Husebø; Audoin, Melanie; Austeng, Andreas; Thomsen, Erik Vilain; Stuart, Matthias Bo; Jensen, Jørgen Arendt

doi:10.1121/10.0010528

Cited by 4 publications

(2 citation statements)

References 16 publications

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“…The amount of divergence is quantified by the FOV, which describes the angular spread of energy in the imaging medium. The thin lens model provides a simple estimation of the FOV of a lensed array based on the paraxial condition assumption but disregards the thickness and losses introduced by the lens [20]. The FOV is given by [19]:…”

Section: Designmentioning

confidence: 99%

Diverging Polymer Acoustic Lens Design for High-Resolution Row–Column Array Ultrasound Transducers

Audoin,

Salari,

Tomov

et al. 2024

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Spherical diverging acoustic lenses mounted on flat 2D Row-Column Addressed (RCA) ultrasound transducers have shown the potential to extend the Field of View (FOV) from a rectilinear to a curvilinear volume region and thereby enable 3D imaging of large organs. Such lenses are usually designed for small aperture low-frequency transducers, which have limited resolution. Moreover, they are made of off-the-shelf pieces of materials, which leaves no room for optimization. We hypothesize that acoustic lenses can be designed to fit highresolution transducers and they can be fabricated in a fast, cost-effective, and flexible manner using a combination of 3D printing and casting or CNC machining techniques. These lenses should increase the FOV of the array while preserving the image quality. In this work, such lenses are made in concave, convex, and compound spherical shapes, and from thermoplastics and thermosetting polymers. Polymethylpentene (TPX), Polystyrene (PS), Polypropylene (PP), Polymethyl methacrylate (PMMA), Polydimethylsiloxane (PDMS) and Room-temperaturevulcanizing silicone (RTV) diverging lenses have been fabricated and mounted on a 128+128 6 MHz RCA transducer. The performances of the lenses have been assessed and compared in terms of FOV, Signal to Noise Ratio (SNR), bandwidth, and potential artefacts. The largest FOV (24.0 • ) is obtained with a 42.64 mm radius PMMA-RTV compound lens, which maintains a decent fractional bandwidth (53%) and SNR at 6 MHz (-9.1 dB amplitude drop compared to the unlensed transducer). The simple PMMA TPX, PS, PP, PDMS and RTV lenses provide a FOV of 12.2 • , 6.3 • , 8.1 • , 11.7 • , 0.6 • and 10.4 • , a fractional bandwidth of 97%, 46%, 103%, 46%, 97%, 53% and 49%, and an amplitude drop of -5.2 dB, -4.4 dB, -2.8 dB, -15.4 dB, -6.0 dB and -1.8 dB respectively. This work demonstrates that thermoplastics are suitable materials for fabricating lowattenuation convex diverging lenses for large-aperture, highfrequency 2D transducers. This is highly desired to achieve highresolution volumetric imaging of large organs.

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Section: Designmentioning

confidence: 99%

Diverging Polymer Acoustic Lens Design for High-Resolution Row–Column Array Ultrasound Transducers

Audoin,

Salari,

Tomov

et al. 2024

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…The current equations in the lensed beamformer give reasonable results, but it has been shown that ray tracing theory can further enhance the quality of the results and increase the field-of-view [62]. This should be further investigated and incorporated in the beamformers.…”

Section: B Lensed Row-column Imagingmentioning

confidence: 99%

Anatomic and Functional Imaging Using Row–Column Arrays

Jensen

Schou

Jorgensen

et al. 2022

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Row-column (RC) arrays have the potential to yield full three-dimensional ultrasound imaging with a greatly reduced number of elements compared to fully populated arrays. They, however, have several challenges due to their special geometry. This review paper summarizes the current literature for RC imaging and demonstrate that full anatomic and functional imaging can attain a high quality using synthetic aperture (SA) sequences and modified delay-and-sum beamforming. Resolution can approach the diffraction limit with an isotropic resolution of half a wavelength with low side-lobe levels, and the field-ofview can be expanded by using convex or lensed RC probes. GPU beamforming allows for 3 orthogonal planes to be beamformed at 30 Hz, providing near real time imaging ideal for positioning the probe and improving the operator's workflow. Functional imaging is also attainable using transverse oscillation and dedicated SA sequence for tensor velocity imaging for revealing the full 3-D velocity vector as a function of spatial position and time for both blood velocity and tissue motion estimation. Using RC arrays with commercial contrast agents can reveal super resolution imaging with isotropic resolution below 20 µm. RC arrays can, thus, yield full 3-D imaging at high resolution, contrast, and volumetric rates for both anatomic and functional imaging with the same number of receive channels as current commercial 1-D arrays.

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