A comparison of methods for focusing the field of a HIFU array transducer through human ribs
| Autor: | Pierre Gélat, G.R. ter Haar, Nader Saffari |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Physics
medicine.medical_specialty Radiological and Ultrasound Technology Phased array Acoustics Transducers Ribs Inverse problem Transducer Apodization Pressure medicine High-Intensity Focused Ultrasound Ablation Humans Radiology Nuclear Medicine and imaging Ray tracing (graphics) Medical physics Phase conjugation Focus (optics) Boundary element method Ultrasonography |
| Zdroj: | Physics in Medicine and Biology. 59:3139-3171 |
| ISSN: | 1361-6560 0031-9155 |
| DOI: | 10.1088/0031-9155/59/12/3139 |
| Popis: | A forward model, which predicts the scattering by human ribs of a multi-element high-intensity focused ultrasound transducer, was used to investigate the efficacy of a range of focusing approaches described in the literature. This forward model is based on the boundary element method and was described by Gélat et al (2011 Phys. Med. Biol. 56 5553-81; 2012 Phys. Med. Biol. 57 8471-97). The model has since been improved and features a complex surface impedance condition at the surface of the ribs. The inverse problem of focusing through the ribs was implemented on six transducer array-rib topologies and five methods of focusing were investigated, including spherical focusing, binarized apodization based on geometric ray tracing, phase conjugation and the decomposition of the time-reversal operator method. The excitation frequency was 1 MHz and the array was of spherical-section type. Both human and idealized rib topologies were considered. The merit of each method of focusing was examined. It was concluded that the constrained optimization approach offers greater potential than the other focusing methods in terms of maximizing the ratio of acoustic pressure magnitudes at the focus to those on the surface of the ribs whilst taking full advantage of the dynamic range of the phased array. |
| Databáze: | OpenAIRE |
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