Suppression of side lobe using distance weight in spectrum of channel signal in medical ultrasound imaging system

Yu Rim Lee; Mok Kun Jeong

doi:10.7776/ASK.2023.42.3.203

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2023 Vol.42, Issue 3 Preview Page Next Page

Research Article

Suppression of side lobe using distance weight in spectrum of channel signal in medical ultrasound imaging system 의료용 초음파 영상 시스템에서 채널신호의 스펙트럼에서 거리 가중치를 이용한 부엽의 억제

31 May 2023. pp. 203-213

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Abstract

In medical ultrasound imaging systems, Side lobes may appear if signals outside the imaging point are not completely removed during receive focusing. If the time signal of the side lobe overlaps with the time signal (main lobe) from the image point, it is difficult to completely remove it using filter processing in the time domain. However, In the receive focusing process, when time-channel signals are Fourier-transformed, the main lobe and side lobe signals are spatially separated in the spectral domain. Therefore, the side lobes can be suppressed by multiplying the image with magnitude weights, which are determined by the magnitudes of the main and side lobes calculated in the spectral domain. In addition, when the main lobe and the side lobe spectrum are adjacent, the distance weight was applied based on the distance between them. In a 5 MHz ultrasound imaging system using a 64-channel linear transducer, point reflector and speckle images with cysts of various brightness were synthesized and weights were applied to the ultrasound image. Using computer simulations, we confirmed that the side lobes were greatly reduced without affecting the spatial resolution in the point reflector image, and the contrast was significantly improved in the cyst image with computer simulations.

Keywords

Medical ultrasound image

Side lobe suppression

Centroid

2 Dimensional Fourier transform

의료용 초음파 영상 시스템에서, 영상점의 밖에서 오는 신호가 초음파 수신 집속 과정에서 완전히 제거되지 않으면 부엽을 발생시킨다. 부엽의 시간 신호가 영상점에서 오는 시간 신호(주엽)와 같이 중첩되어 나타나면 시간 영역에서 필터 처리를 이용하여 완전히 제거하기 어렵다. 그러나 수신 집속 과정에서 시간 -채널 신호를 푸리에 변환하면, 주엽과 부엽의 신호는 주파수 스펙트럼 영역에서 공간적으로 분리가 된다. 따라서 스펙트럼 영역에서 계산한 주엽과 부엽의 신호크기를 이용하여 크기 가중치를 계산하여 영상에 곱함으로써 부엽을 억제하였다. 그리고 주엽과 부엽의 스펙트럼이 인접할 때, 주엽과 부엽 스펙트럼 사이의 거리에 따라 거리 가중치를 적용하였다. 64 채널 선형 트랜스듀서를 사용하는 5 MHz의 초음파 영상 시스템에서 점확산 영상과 다른 밝기의 낭종을 가지는 스페클 영상을 합성하고 가중치를 적용하여 초음파 영상을 계산하였다. 점반사체 영상에서 해상도의 변화 없이 부엽이 크게 줄어들었으며 낭종 영상에서 대조도가 크게 개선됨을 컴퓨터 시뮬레이션으로 확인하였다.

키워드

의료용 초음파 영상

수신 집속

부엽 억제

2차원 푸리에 변환

References

J. A. Jensen and N. B. Svendsen, "Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 39, 262-267 (1992). 10.1109/58.13912318263145

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. Control, 54, 343-358 (2007). 10.1109/TUFFC.2007.24817328331

J. A. Mann and W. F. Walker, "A constrained adaptive beamformer for medical ultrasound: Initial results," Proc. IEEE Ultrason. Symp. 2, 1807-1810 (2002).

J. F. Synnevag, A. Austeng, and S. Holm, "Benefits of minimum-variance beamforming in medical ultrasound imaging," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 56, 1868-1879 (2009). 10.1109/TUFFC.2009.126319811990

R. F. Wagner, M. F. Insana, and S. W. Smith, "Fundamental correlation lengths of coherent speckle in medical ultrasonic images," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 35, 34-44 (1988). 10.1109/58.414518290126PMC5567795

Y. Wang, H. Peng, C. Zheng, Z. Han, and H. Qiao, "A dynamic generalized coherence factor for side lobe suppression in ultrasound imaging," Comput. Biol. Med. 116, 103522 (2020). 10.1016/j.compbiomed.2019.10352231739004

M. A. L. Bell, R. Goswami, J. A. Kisslo, J. J. Dahl, and G. E. Trahey, "Short-lag spatial coherence imaging of cardiac ultrasound data: Initial clinical results," Ultrasound Med. Biol. 39, 1861-1874 (2013). 10.1016/j.ultrasmedbio.2013.03.02923932276PMC3966558

M. A. L. Bell, J. J. Dahl, and G. E. Trahey, "Resolution and brightness characteristics of short-lag spatial coherence (SLSC) images," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 62, 1265-1276 (2015). 10.1109/TUFFC.2014.00690926168173PMC4821635

T. A. Gallagher, A. J. Nemeth, and L. Hacein-Bey, "An introduction to the Fourier transform: relationship to MRI," Am. J. Roentgenol, 190, 1396-1405 (2008). 10.2214/AJR.07.287418430861

D. Gottleib, B. Gustafsson, and P. P. Forssen, "On the direct Fourier method for computer tomography," IEEE Trans. Medical Imag. 19, 223-232 (2000). 10.1109/42.84518010875706

M. M. Bronstein, A. M. Bronstein, M. Zibulevsky, and H. Azhari, "Reconstruction in diffraction ultrasound tomography using nonuniform FFT," IEEE T-MI, 21, 1395-1401 (2002). 10.1109/TMI.2002.80642312575876

W. F. Walker and G. E. Trahey, "The application of k-space in pulse echo ultrasound," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 45, 541-558 (1998). 10.1109/58.67759918244206

K. Nagai, "A new synthetic-aperture focusing method for ultrasonic B-scan imaging by the Fourier transform," IEEE Trans. Son. and Ultrason. 32, 531-536 (1985). 10.1109/T-SU.1985.31627

T. Stepinski, "An implementation of synthetic aperture focusing technique in frequency domain," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 54, 1399-1408 (2007). 10.1109/TUFFC.2007.40017718329

M. K. Jeong, "A Fourier transform-based sidelobe reduction method in ultrasound imaging," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 47, 759-763 (2000). 10.1109/58.84206618238606

M. K. Jeong and S. J. Kwon, "Estimation of side lobes in ultrasound imaging systems," Biomed Eng. Lett. 5, 229-239 (2015). 10.1007/s13534-015-0194-y

M. K. Jeong, "Suppression of side lobe and grating lobe in ultrasound medical imaging system" (in Korean), J. Acoust. Soc. Kr. 41, 525-533 (2022).

A. Rodriguez-Molares, O. M. H. Rindal, J. D'hooge, S. E. Masoy, A. Austeng, M. A. L. Bell, and H. Torp, "The generalized contrast-to-noise ratio: A formal definition for lesion detectability," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 67, 745-759 (2019). 10.1109/TUFFC.2019.295685531796398PMC8354776

R. F. Wagner, "Statistics of speckle in ultrasound B-scans," IEEE Trans. Son. Ultrason. 30, 156-163 (1983). 10.1109/T-SU.1983.31404

T. A. Tuthill, R. H. Sperry, and K. J. Parker, "Deviations from Rayleigh statistics in ultrasonic speckle," Ultrasonic imaging, 10, 81-89 (1988). 10.1177/0161734688010002013057714

M. K. Jeong and S. J. Kwon, "A new method for assessing the performance of signal processing filters in suppressing the side lobe level," USG, 40, 289-300 (2021). 10.14366/usg.2003232847340PMC7994734

Information

Publisher :The Acoustical Society of Korea
Publisher(Ko) :한국음향학회
Journal Title :The Journal of the Acoustical Society of Korea
Journal Title(Ko) :한국음향학회지
Volume : 42
No :3
Pages :203-213
Received Date : 2023-02-23
Revised Date : 2023-04-17
Accepted Date : 2023-05-01
DOI :https://doi.org/10.7776/ASK.2023.42.3.203

The Journal of the Acoustical Society of KoreaISSN:1225-4428(Print) 2287-3775(Online)한국음향학회

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