Acoustic Imaging by Wave Field Extrapolation Part II: Practical Aspects

Ridder, Jeroen de; Berkhout, A. J.; Wal, L.F. van der

doi:10.1007/978-1-4684-3944-1_34

Cited by 16 publications

(4 citation statements)

References 1 publication

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“…Completely computer-focused ultrasound imaging using a wide-angle ultrasound burst has been achieved using the ultrasound holographic 8 (UHB) method. Although similar ultrasound technique is under investigation elsewhere, 6 ·u to our knowledge the present results are the first successful tissue images obtained with an operational scanner based on wide-angle completely computer-focused imaging.…”

Section: Discussionmentioning

confidence: 79%

“…Later, Hanstead 5 produced a system based on line-by-line holographic reconstruction of images for NOT (nondestructive testing) purposes. Ridder et al, 6 using the socalled wavefield extrapolation method, achieved interesting resolution results in computer simulations. So far, however, despite the efforts to apply these princi-pies to improve resolution and tissue characterization in medical imaging, no practical results of actual tissue imaging have been reported.…”

mentioning

confidence: 99%

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Completely computer-focused ultrasound imaging. First clinical imaging results.

Koivukangas

Tervonen²,

Alasaarela³

et al. 1989

Journal of Ultrasound in Medicine

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Completely computer-focused ultrasound imaging has been achieved using the UHB (ultrasound holographic B) method. This is a synthetic aperture method that combines ultrasonic holography and the conventional B-scan method. A wide-angle ultrasound burst (4 MHz) is transmitted into the object and the reflected echoes are measured as a function of the propagation time, but both the amplitude and phase angle are recorded, giving multiple one-dimensional holograms in a cross-sectional plane. This UHB data is rearranged to obtain one-dimensional wave fields, which represent the wave fronts reflected from each depth. The image is then reconstructed by propagating these wave fields backward to their original positions on the image using Fourier transform, a spectrum shift theorem, and inverse Fourier transform. The whole UHB image is obtained by calculating the intensity lines from these wave fields and by scanning these lines one by on the cathode ray tube (CRT) monitor. Following extensive laboratory testing with single and multielement transducers, special 32- and 64-element linear array transducers were fabricated, as was computer software capable of producing a UHB image in 40 seconds. Tissue imaging tests followed by clinical imaging of 30 patients showed that images obtained with this prototype compared favorably with those obtained by state-of-the-art conventional ultrasound scanners. The potential advantages of the new method are enhanced lateral resolution and the incorporation of phase information in tissue characterization. This would be important in diagnostic and intraoperative, especially neurosurgical, imaging.

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Section: Discussionmentioning

confidence: 79%

mentioning

confidence: 99%

Completely computer-focused ultrasound imaging. First clinical imaging results.

Koivukangas

Tervonen²,

Alasaarela³

et al. 1989

Journal of Ultrasound in Medicine

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“…We considered spherical-wave insonification by a source which was a spatial and temporal impulse of strength A. If the source region is included in (5), the wave equation for the incident pressure becomes (8) where x i is the vector from the origin to a source at x i as shown in Fig. 1.…”

Section: B Impulse Responsementioning

confidence: 99%

Imaging via inversion of ellipsoidal projections of solutions to the linear acoustic wave equation (medical ultrasound)

Arthur¹,

Broadstone²

1989

IEEE Trans. Med. Imaging

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Backscattered energy from a medium with nearly constant velocity measured by an omnidirectional source-sensor comes from spherical shells centered at the source-sensor location. If source and sensor locations differ, the energy comes from ellipsoidal shells. To image the scattering potential or reflectivity of the medium, backscattered energy must be projected onto ellipsoids with a weighting factor dependent on the eccentricity of the ellipsoid. Eccentricity is the ratio of the separation of source and sensor to the path length from source to scatterer to sensor. Because path length changes with time, this weighting factor is, in general, time-dependent. It is consistent only if the source and sensor location are the same, in which case its value is unity. To estimate scattering potential or reflectivity at a given site, the backscattered signal which could have arisen from that site as measured by a given source-sensor pair is weighted by that pair's time-dependent ellipsoidal factor, then the weighted backscattered signals are averaged over all available source-sensor pairs.

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“…I MAGE reconstruction from projection data is a computation-intensive task [1]. For example, synthetic-focus images with the complete dataset produced by pulseecho ultrasonic systems with N-element transducers contain the effect of averaging samples from N 2 backscattered signals at each pixel in the image [2], [3]. Focus-andsteer images, which are typical of conventional ultrasonic imaging systems, also combine the effect of N 2 signal samples at each pixel [4], [5].…”

Section: Introductionmentioning

confidence: 99%

Determination of time-of-flight surfaces using the method of moments (US imaging)

Broadstone

Arthur

1991

IEEE Trans. Med. Imaging

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To produce an image from backscattered signals requires a knowledge of the time of flight from each source to each sensor in a transducer array. The authors reduced the determination of the rectangular coordinates of a new point on any time-of-flight surface, which requires finding the square root of the sum of squares, to the time of a single addition. To do this, the time-of-flight surface was represented by a two-dimensional, positive-integer-degree polynomial and then that polynomial was implemented in its forward-difference form. Two solutions for such a polynomial were found using the method of moments. A minimum-mean-square-error constraint yields polynomial coefficients from a numeric evaluation of the moments of arbitrary surfaces over rectangular regions, and an analytical solution for moments of time-of-flight surfaces over sector-shaped regions. For a 7x6-cm region at a minimum range of 4 cm centered in a 74 degrees sector, the maximum error for a second-degree polynomial was 0.30% of the average time of flight over the region for the numeric solution and 0.32% for the analytic solution, assuming a 1500-m/s background velocity.

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Acoustic Imaging by Wave Field Extrapolation Part II: Practical Aspects

Cited by 16 publications

References 1 publication

Completely computer-focused ultrasound imaging. First clinical imaging results.

Completely computer-focused ultrasound imaging. First clinical imaging results.

Imaging via inversion of ellipsoidal projections of solutions to the linear acoustic wave equation (medical ultrasound)

Determination of time-of-flight surfaces using the method of moments (US imaging)

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