Non-cylindrical transmission focusing for large depth of field

Umemura, Shin Ichiro; Azuma, Takashi; Miwa, Yoshihiro; Sasaki, Keisuke; Sugiyama, T.; Hayashi, Tetsuya; Kuribara, Hiroshi

doi:10.1109/ultsym.2002.1192629

Cited by 5 publications

(6 citation statements)

References 2 publications

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“…2.1.3. Non-cylindrical focusing method 18) . The delay time t nc applied to the ultrasonic element at position ( ) x , 0 n in the non-cylindrical transmission focusing method is calculated as…”

Section: Transmission Focusing Methodsmentioning

confidence: 99%

“…Hence, it is necessary to control ultrasonic beams to improve the spatial homogeneity of PSFs. As the lateral width of a conventional focused beam changes along the axial direction, hybrid 16,17) and non-cylindrical 18) focusing methods were proposed to realize a uniform beam width along the axial direction. The hybrid focusing method was developed for a 2D matrix concave array.…”

Section: Introductionmentioning

confidence: 99%

“…16) This focusing method was also applied to form a push beam in shear wave elastography. 17) Umemura et al 18) compared the non-cylindrical focusing method with the conventional one based on schlieren images of the transmission beams. Also, as a mismatch between actual and assumed speeds of sound (SoSs) influences both transmit focusing and receive beamforming, proper SoSs need to be used in both processes.…”

Section: Introductionmentioning

confidence: 99%

“…For this aim, in the present study, three transmission focusing methods, i.e. the conventional, hybrid, 16,17) and non-cylindrical 18) focusing methods, with correction of SoS were evaluated to achieve an ultrasonic beam with a uniform lateral width. Numerical simulations using Field II 32,33) were performed for investigation of these transmission focusing methods which were evaluated based on DOFs and lateral beam widths at different axial positions.…”

Section: Introductionmentioning

confidence: 99%

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Effects from correction of speed of sound in transmit and receive beamforming using focus beam

Nagaoka¹,

Yoshizawa²,

Umemura³

et al. 2021

Jpn. J. Appl. Phys.

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In this study, focusing methods were investigated for generation of an ultrasonic beam with a uniform lateral width across the axial imaging field of view through numerical simulation using Field II. Also, the influence of the mismatch between the speed of sound (SoS) assumed in beamforming process and actual one was evaluated by wire and cyst phantom experiments. In the simulation, conventional, hybrid, and non-cylindrical focusing methods were evaluated based on the evaluation metrics, i.e. depth of field and lateral beam width. For the three focusing methods, the proper imaging parameters were determined based on the simulation results. In the phantom experiments, the lateral resolution was improved by correcting the SoS in receive beamforming. Additionally, the correction of the SoS in transmission focusing improved the uniformity of beam width and image contrast.

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Section: Transmission Focusing Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects from correction of speed of sound in transmit and receive beamforming using focus beam

Nagaoka¹,

Yoshizawa²,

Umemura³

et al. 2021

Jpn. J. Appl. Phys.

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“…To enlarge the power deposition pattern of ultrasonic focusing, a few methods of nonspherical, noncylindrical focusing have been proposed for therapy [14][15][16] and imaging. [17][18][19] In this study, time reversal is employed to obtain nonspherically focused heating waves forming an enlarged focus to cover all the cavitation clouds generated by multiple trigger pulses. The cavitation cloud distribution as well as the heating-wave focus may therefore be enlarged in the direction either parallel or perpendicular to the direction of ultrasound propagation.…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic Coagulation of Large Tissue Region by Generating Multiple Cavitation Clouds in Direction Perpendicular to Ultrasound Propagation

Inaba¹,

Moriyama²,

Yoshizawa³

et al. 2011

Jpn. J. Appl. Phys.

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High-intensity focused ultrasound (HIFU) therapy is attracting attention as a minimally invasive therapeutic modality. However, it has a problem of a long treatment time. To improve the efficiency of the treatment, we developed a method of coagulating a large region at one time utilizing multiple clouds of cavitation. It is known that acoustic cavitation generated in the focal region of HIFU enhances tissue heating. In this study, cavitation clouds were generated at three positions in the direction perpendicular to ultrasound propagation using high-intensity ultrasound pulses. The tissue in the vicinity of the cavitation clouds was coagulated simultaneously with nonspherically focused ultrasound waves at a relatively low intensity. A high-speed camera was used to observe such behavior of cavitation clouds in a tissue-mimicking gel and to optimize the sequence, and the coagulation performance of the sequence was confirmed with an experiment using excised tissue. The result suggests that the HIFU treatment time is significantly shortened by employing the proposed method.

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Hybrid beamforming and steering with reconfigurable arrays

Hooi¹,

Thomenius

Fisher

et al. 2010

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Reconfigurable arrays offer an advantage over traditional ultrasound arrays because of their flexibility in channel selection. To improve ultrasound beamforming and coverage through beam steering, we propose a hybrid beamforming technique to elongate the depth of focus of transmit beams and a method of element selection that improves steering capabilities that take advantage of array reconfigurability using annular rings. A local minimization technique to optimize the hybrid aperture is discussed in this paper. The chosen hybrid apertures covering four focal zones result in improved range in depth of focus when compared with pure spherical beams via point spread functions (PSF) and lesion signal-tonoise ratio (LSNR) calculations. Improvements were statistically significant at focal depth extremes. Our method of beam steering utilizing a quantized phase delay selection to minimize delay errors indicated better performance by removing an artifact present with traditional ringed element selection.

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Non-cylindrical transmission focusing for large depth of field

Cited by 5 publications

References 2 publications

Effects from correction of speed of sound in transmit and receive beamforming using focus beam

Effects from correction of speed of sound in transmit and receive beamforming using focus beam

Ultrasonic Coagulation of Large Tissue Region by Generating Multiple Cavitation Clouds in Direction Perpendicular to Ultrasound Propagation

Hybrid beamforming and steering with reconfigurable arrays

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