Fig. 1. Architecture of delay-and-sum beamforming system using array transducer.
Fig. 2. Waveforms of echoes across transducer array: (a) from imaging p oint and ( b) not f rom imaging point.
Fig. 3. Weighting values as a function of centroid in a 64 channel imaging system: triangular weight (solid) and weight corresponding to the fourth power of the Hamming window (dashed).
Fig. 4. Temporal evolution of channel RF waveform due to cavitation.
Fig. 5. Images of a point like bubble obtained using (a) DAS without compression and (b) MVB with 40 dB logarithmic compression.
Fig. 6. 2-D maps of (a) centroid weighting, (b) flatness, and (c) multiplication of centroid weighting and flatness.
Fig. 7. Images obtained using (a) weighted DAS and (b) weighted MVB, both with a 40 dB log compression.
Fig. 8. Lateral field responses: DAS (solid), weighted DAS (dotted), MVB (dashed), and weighted MVB (dash-dotted).
Fig. 9. Axial field responses: DAS (solid), weighted DAS (dotted), MVB (dashed), and weighted MVB (dash-dotted).
Fig. 10. Experimental setup.
Fig. 11. Experimental setup: (a) relative placement of shock wave generation and imaging probes for alignment and (b) B-mode image of cavitation due to shock wave.
Fig. 13. (a) RF echo from single bubble collapse, (b) DAS image, (c) MVB image, (d) RF echo from two adjacent bubble collapse, (e) DAS image, and (f) MVB image.
Fig. 12. Part of 64 channels of RF data.
Fig. 15. B-mode images of (a) weighted single bubble collapse using DAS, (b) weighted single bubble collapse using MVB, (c) weighted two bubble collapse using DAS, and (d) weighted two bubble collapse using MVB.
Fig. 14. Plots of (a) centroid weighting from single bubble collapse data, (b) uniformity of single bubble collapse image, (c) weighting factor obtained by multiplying together centroid weighting and flatness of single bubble collapse image, (d) centroid weighting from two adjacent bubble collapse data, (e) flatness of two bubble collapse image, and (f) weighting factor obtained by multiplying together centroid weighting and flatness of two bubble collapse image.
References
- V. A. Salgaonkar, S. Datta, C. K. Holland, and T. D. Mast, "Passive cavitation imaging with ultrasound arrays," J. Acoust. Soc. Am. 126, 3071-3083 (2009). https://doi.org/10.1121/1.3238260
- P. Boulos, F. Varray, A. Poizat, J. C. Bera, and C. Cachard, "Passive cavitation imaging using an open ultrasonic system and time reversal reconstruction," Proc. 22nd French Mechanics Congress (2015).
- C. Coviello, R. J. Kozick, J. J. Choi, M. Gyöngy, J. Collin, C. Jensen, P. P. Smith, and C. C. Coussios, "Passive acoustic mapping using optimal beamforming for real-time monitoring of ultrasound therapy," Proc. Meetings on Acoustics, 1-7 (2013).
- P. Boulos, F. Varray, A. Poizat, M. A. Kalkhoran, B. Gilles, J. C. Bera, and C. Cachard, "Passive cavitation imaging using different advanced beamforming methods," Proc. IEEE Ultrasonics Symposium (2016).
- J. H. Song, S. Cochran, P. Prentice, G. McLeod, and G. Corner, "Role of periodic shock waves in passive acoustic mapping of cavitation," Proc. IEEE Ultrasonics Symposium (2016).
- M. Gyongy and C. C. Coussios, "Passive spatial mapping of inertial cavitation during HIFU exposure," IEEE Trans. Biomedical Engineering, 57, 48-56 (2010). https://doi.org/10.1109/TBME.2009.2026907
- J. A. Jensen and N. B. Svendsen, "Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers," IEEE Trans. Ultrason. Ferroelectr. Freq. Contr., 39, 262-267 (1992). https://doi.org/10.1109/58.139123
- D. A. Guenther and W. F. Walker, "Optimal apodization design for medical ultrasound using constrained least squares. Part I: Theory," IEEE Trans. Ultrason. Ferroelectr. Freq. Contr., 54, 332-342 (2007). https://doi.org/10.1109/TUFFC.2007.247
- D. A. Guenther and W. F. Walker, "Optimal apodization design for medical ultrasound using constrained least squares. Part II: Simulation results," IEEE Trans. Ultrason. Ferroelectr. Freq. Contr., 54, 343-358 (2007). https://doi.org/10.1109/TUFFC.2007.248
- I. K. Holfort, F. Gran, and J. A. Jensen, "Broadband minimum variance beamforming for ultrasound imaging," IEEE Trans. Ultrason. Ferroelectr. Freq. Contr., 56, 314-325 (2009). https://doi.org/10.1109/TUFFC.2009.1040
- K. Kim, S. Park, J. Kim, S. B. Park, and M. H. Bae, "A fast minimum variance beamforming method using principal component analysis," IEEE Trans. Ultrason. Ferroelectr. Freq. Contr., 61, 930-945 (2014). https://doi.org/10.1109/TUFFC.2014.2989