UYARLAMALI ALTDİZİSEL SİNYAL İŞLEME İÇİN VERİ ALMA TEKNİKLERİ

öz UYARLAMALI ALTDİZİSEL SİNYAL İŞLEME İÇİN VERİ ALMA TEKNİKLERİ Tavlı, Bülent Yüksek Lisans, Elektrik ve Elektronik Mühendisliği Bölümü Tez Yöneticisi: Doç. Dr. Mustafa Karaman Ağustos 1998, 60 sayfa Temel olarak çok elemanlı yapay açıklık ve evreli dizi yaklaşımlarına dayanan ultrasonik altdizisel sinyal işleme yöntemi, düşük maliyetli gerçek zamanda görüntüleme yapabilen sistemleri olanaklı kılmaktadır. Fakat, altdizisel sinyal işleme yönteminde, herhangi bir demet çizgisini oluşturabilmek amacıyla birden çok gönderiş-alış yapılması doku/transdüser hareketlerinin alınan eko sinyalleri arasında ciddi faz bozuklukları oluşturmasına neden olabilir. Faz bozukluklarını düzeltmek amacıyla referans eko sinyalleri kullanılarak korelasyon işlemi yapılabilir. Bu işlemin doğruluğu ve güvenilirliği sinyaller arası korelasyon seviyesi ile doğrudan ilişkilidir. Komşu alış altdizilerinirı tüm elemanları yerine, seçilmiş elemanlardan alınan sinyaller referans olarak kullanıldığında daha yüksek korelasyon seviyelerine ulaşılabilmektedir. Bu çalışmada uyarlamalı altdizisel sinyal işleme yönteminde komşu alış altdizilerinin seçilmiş elemanlarından elde edilen yüksek korelasyonlu referans sinyaller kullanılarak hareket tahmin ve telafi metodları araştırılmıştır. Yüksek korelasyonlu referans sinyaller elde etmek için iki yeni veri alma yapısının yanısıra standart altdizi yöntemi de incelenmiştir. Farklı referans sinyalleri kullanan uyarlamalı altdizisel sinyal işleme yöntemi, 128 elemanlı 3.5 MHz'de çalışan bir transdüser dizisi tarafından farklı iki deney fantomundan alınan veriler üzerinde test edilmiştir. Sonuçlar önerilen uyarlamalı altdizisel sinyal işleme yönteminin, çeyrek dalga boyuna kadar olan doku/transdüser hareketlerinin etkin bir biçimde tahmin ve telafi edebildiğini göstermektedir. Anahtar Kelimeler: Ultrason, Altdizisel Sinyal İşleme, Hareket Tahmini

ABSTRACT DATA ACQUISITION TECHNIQUES FOR ADAPTIVE SUBAPERTURE PROCESSING Tavli, Bülent MSc, Department of Electrical and Electronics Engineering Supervisor: Assoc. Prof. Dr. Mustafa Karaman August 1998, 60 pages Ultrasonic subaperture processing, based on multi-element synthetic aperture and phased array approaches, permits low-cost real-time imaging systems. Presence of tissue/transducer displacements during the multiple subaperture firing-receptions may induce significant phase distortions on received echo signals. Correlation processing using reference echo signals can be used for correction of phase distortions, where the accuracy and robustness are critically limited by the signal redundancy (i.e. correlation). Reference signals derived from the subset of elements of neighboring subapertures with high redundancy exhibit higher correlation than the signals collected from entire subaperture. In this study, we explore adaptive subaperture processing with motion compensation through correlation processing using highly correlated reference signals derived from neighboring receive subapertures. Two new data acquisition schemes for collection of redundant reference signal sets are investigated together with standart subaperture approach. Adaptive subaperture processing with different reference signal sets is tested using experimental rf-data acquired from two different phantoms with 3.5 MHz, 128-element transducer array. The results show that tissue/transducer motion up to a quarter of a wavelength can be effectively compensated in real-time adaptive subaperture processing. Keywords: Ultrasound, Subaperture Processing, Motion Estimation

REFERENCES [1] A.Shoup and J. Hart, "Ultrasonic imaging systems," Proc. of IEEE Ultrason. Symp., pp. 863-871, 1988. [2] K. E. Thomenius, "Evolution of ultrasound beamformers," Proc. of IEEE Ultrason. Symp., pp. 1615-1622, 1996. [3] Y. Ozaki, H. Sumitani, T. Tomoda, and M. Tanaka, "A new system for real time synthetic aperture ultrasonic imaging," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 35, pp. 828-838, 1988. [4] D. K. Peterson and G. S. Kino, "Real-time digital image reconstruction: a description of imaging hardware and an analysis of, quantization errors," IEEE Trans. Sonics Ultrason., vol. 31, pp.337-351, 1984. [5] G. E. Trahey and L. F. Nock, "Synthetic receive aperture imaging with phase correction for motion and for tissue inhomogeneities-part I: basic principles," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 39, pp. 496-501, 1992. [6] C. H. Frazier and W. D. O'Brien, Jr., "Synthetic receive aperture techniques with a virtual source element," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 45, pp. 196-207, 1998. [7] M. Karaman, P. C. Li and M. O'Donnell, "Synthetic Aperture Imaging for Small Scale Systems," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 42, pp. 429-442, 1995. [8] F. N. Uçar and M. Karaman, "Beam space processing for low-cost scanners," Proc. of IEEE Ultrason. Symp., pp. 1349-1352, 1996. [9] M. O'Donnell, M. J. Eberle, D. N. Stephens, J. L. Litzza, K. S. Vicente, and B. M. Shapo, "Synthetic phased arrays for intraluminal imaging of coronary arteries," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 44, pp. 714-721, 1997. [10] M. Karaman and M. O'Donnell, "Subaperture processing for ultrasonic imaging," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 45, pp. 126-135, 1998. [11] G. E. Trahey and L. F. Nock, "Synthetic receive aperture imaging with phase correction for motion and for tissue inhomogeneities-part II: effects of and correction for motion," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 39, pp. 496-501, 1992. [12] H. Ş. Bilge, M. Karaman and M. O'Donnell, "Motion estimation using common spatial frequencies in synthetic aperture imaging", Proc. of IEEE Ultrason. Symp., pp. 1551-1554, 1996.

[13] M. Karaman, H. Ş. Bilge and M. O'Donnell, "Adaptive multi-element synthetic aperture imaging with motion and phase aberration correction," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., 1998. [14] R. A. Harris, D. H. Follett, M. Halliwell, and P. N. T. Wells, "Ultimate limits in ultrasonic image resolution," Ultrasound in Med. & Biol., vol. 17, pp. 547-558, 1991. [15] M. Hirama and T. Sato "Imaging through an inhomogeneous layer by leastmean-square error fitting," J. Acoust. Soc. Amer., vol. 75, pp. 1142-1147, 1984. [16] L. Nock, G. E. Trahey, and S. W. Smith "Phase aberration correction in medical ultrasound using brightness as a quality factor," J. Acoust. Soc. Amer., vol. 85, pp. 1819-1833, 1989. [17] M. Soumekh and H. Yang "Complex phase error and motion estimation in synthetic aperture radar imaging," Proc. of SPIE, Image Process. and Algo. Tech., vol. 1452, pp. 104-113, 1991. [18] M. Karaman, A. Atalar, H. Köymen, and M. O'Donnell "A phase aberration correction method in ultrasound imaging," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 40, pp. 275-281, 1993. [19] G. E. Trahey, S. W. Smith, anf O. T. Von Ramm, "Speckle pattern correlation with lateral aperture translation: experimental results and implications for spatial compounding," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 33, pp. 257-264, 1986. [20] Y. Li, "Phase aberration correction using near-field signal redundancy-part I: principles," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 44, pp. 355-371, 1997. [21] R. Mallart and M. Fink "The van cittert-zernike theorem in pulse-echo measurements," J. Acoust. Soc. Amer., vol. 90, pp. 2718-2727, 1991. [22] R. C. Gonzalez and R. E. Woods, Digital image processing, Addison-Wesley Publishing Company, Inc., 1993. [23] Z. H. Cho, J. P. Jones, and M. Singh, Foundations of medical imaging, John Wiley & Sons Inc., 1993. [24] H. E. Karrer and A. M. Dickey, "Ultrasound imaging: an overview," Hewlett- Packard journal, vol. 34, pp. 3-6, 1983. [25] K. K. Shung, M. B. Smith, and B. Tsui, Principles of medical imaging, Academic press limite, 1992. [26] G. S. Kino, Acoustic waves: devices, imaging and analog signal processing, Prentice-Hall, Englewood Cliffs, NJ, 1987. [27] A. Macovski, Medical imaging systems, Prentice-Hall, Englewood Cliffs, NJ, 1983.

[28] E. Krestel, Imaging systems for medical diagnostics, Siemens Aktiengesellschaft, 1990. [29] A. P. Pierce Acoustics: an introduction to its physical principles and applications, Acoustical Society of America, 1991. [30] D. H. Johnson and D. E. Dudgeon, Array signal processing concepts and techniques, Prentice-Hall, Englewood Cliffs, NJ, 1993. [31] B. D. Van Veen and K. M. Buckley, "Beamforming: a versatile approach to spatial filtering," IEEE ASSP Magazine, vol. 5, pp. 4-24, 1988. [32] D. E. Dudgeon and R. M. Mersereau, Multidimensional digital signal processing, Prentice-Hall, Englewood Cliffs, NJ, 1984. [33] J. W. Goodman, Statistical optics, New York: Wiley-Interscience, 1985. [34] B. D. Steinberg, Principles of aperture and array system design, New York: Wiley, 1976. [35] G. R. Lockwood, P. C. Li, M. O'Donnell and F. S. Foster, "Optimizing the radiation pattern of sparse periodic linear arrays," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 43, pp. 7-14, 1996. [36] R. Y. Chiao and L. J. Thomas, "Aperture formation on reduced-channel arrays using the transmit-receive apodization matrix," Proc. of IEEE Ultrason. Symp., pp. 1567-1571, 1996. [37] B. Tavlı and M. Karaman, "An efficient motion estimation technique for ultrasonic subaperture imaging," Accepted to 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1998. [38] M. Karaman and B. Tavlı, "Motion estimation using selective signal redundancy in subaperture processing," Accepted to IEEE International Ultrasonics Symposium, 1998. [39] A.V. Oppenheim and R. Schafer, Discrete time signal processing, Prentice- Hall, Englewood Cliffs, NJ, 1989. [40] P.-C. Li and M. O'Donnell, "Improved detectibility with blocked element compensation," Ultrasonic Imaging, vol. 16, pp. 1-18, 1994.