Martin, EM;
Zhang, EZ;
Guggenheim, JA;
Beard, PC;
Treeby, BE;
(2017)
Rapid Spatial Mapping of Focused Ultrasound Fields Using a Planar Fabry-Pérot Sensor.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
, 64
(11)
pp. 1711-1722.
10.1109/TUFFC.2017.2748886.
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Abstract
Measurement of high acoustic pressures is necessary in order to fully characterise clinical high-intensity focused ultrasound (HIFU) fields, and for accurate validation of computational models of ultrasound propagation. However, many existing measurement devices are unable to withstand the extreme pressures generated in these fields, and those that can often exhibit low sensitivity. Here, a planar Fabry-Pérot interferometer with hard dielectric mirrors and spacer was designed, fabricated, and characterised and its suitability for measurement of nonlinear focused ultrasound fields was investigated. The noise equivalent pressure of the scanning system scaled with the adjustable pressure detection range between 49 kPa for pressures up to 8 MPa and 152 kPa for measurements up to 25 MPa, over a 125 MHz measurement bandwidth. Measurements of the frequency response of the sensor showed that it varied by less than 3 dB in the range 1 - 62 MHz. The effective element size of the sensor was 65 μm and waveforms were acquired at a rate of 200 Hz. The device was used to measure the acoustic pressure in the field of a 1.1 MHz single element spherically focused bowl transducer. Measurements of the acoustic field at low pressures compared well with measurements made using a PVDF needle hydrophone. At high pressures, the measured peak focal pressures agreed well with the focal pressure modelled using the Khokhlov-Zabolotskaya-Kuznetsov equation. Maximum peak positive pressures of 25 MPa, and peak negative pressures of 12 MPa were measured, and planar field scans were acquired in scan times on the order of 1 minute. The properties of the sensor and scanning system are well suited to measurement of nonlinear focused ultrasound fields, in both the focal region and the low pressure peripheral regions. The fast acquisition speed of the system and its low noise equivalent pressure are advantageous, and with further development of the sensor, it has potential in application to HIFU metrology.
| Type: | Article |
|---|---|
| Title: | Rapid Spatial Mapping of Focused Ultrasound Fields Using a Planar Fabry-Pérot Sensor |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1109/TUFFC.2017.2748886 |
| Publisher version: | https://doi.org/10.1109/TUFFC.2017.2748886 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons Attribution 3.0 License. For more information, see http://creativecommons.org/licenses/by/3.0/. |
| Keywords: | HIFU, Field mapping, Fabry-Pérot, Acoustic pressure measurement |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1572384 |
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