Biomedical subjects

E J Boote

Publications and source records attributed to E J Boote.

5 recordsLinked to original sources

PubMed1991

Improved resolution backscatter coefficient imaging.

This paper reports the extension of a method for imaging acoustic backscatter coefficients that allows for greater spatial resolution in the resulting images. This is done by using a broad-band excitation pulse and short-duration time gates in the analysis. The images produced had better spatial resolution than the previously reported technique [Ultrasonic Imaging 10, 121-138]. Furthermore, the pixel values were based upon quantitatively accurate backscatter coefficients at given spatial locations. The paper also discusses the additional computational requirements of greater spatial resolution and proposes a least-squares fit to a smoothly varying set of sparse data to generate the data points in between.

Ultrasonics↗

PubMed1989

Accurate depth-independent determination of acoustic backscatter coefficients with focused transducers.

The accuracy of a method of data reduction for determining acoustic backscatter coefficients was tested using focused transducers and narrow-band pulses. Two phantoms with well-defined scattering properties were the bases of the tests, one having low attenuation and one with tissue-mimicking attenuation. The experimentally determined backscatter coefficients were found to be independent of transducer-to-scattering-volume distance and to agree very well with theoretical values, typically within 10%.

Acoustic Stimulation↗

PubMed1988

Instrument-independent acoustic backscatter coefficient imaging.

This paper presents an adaptation of a method for determining acoustic backscatter coefficients to produce quantitative ultrasound images. Backscattered echo signals are recorded from a region to be imaged and backscatter coefficients are determined and related to spatial position. The values of the backscatter coefficients are then translated into a gray scale image. Testing of this imaging technique has been performed using tissue-mimicking phantoms which contain sections having backscatter coefficients different from that of the surrounding material. The technique has also been tested using a phantom in which a fat-mimicking layer is interposed between the acoustic window and the main body of the phantom. The images produced were found to be quantitatively accurate throughout the phantom, including the sections with differing backscatter. Quantitative accuracy did not suffer when the fat-mimicking layer was present.

Models, Structural↗

PubMed1988

Performance tests of Doppler ultrasound equipment with a tissue and blood-mimicking phantom.

A tissue- and blood-mimicking phantom was assembled for assessing the performance of ultrasound Doppler equipment. The phantom is in the shape of a rectangular parallelepiped with a 10 x 20 cm scanning window and a depth of 16 cm. Components of the phantom include a tissue-mimicking material, 7.9 mm diameter simulated vessels, a fluid with similar back-scatter as whole blood, and a peristaltic pumping system producing peak scatterer velocities greater than 1 m/sec. Performance tests done with the phantom are outlined. These include assessments of the maximum depth of penetration and of the directional discrimination capabilities of the instrument, determinations of the accuracy of displayed flow velocities, and accuracy assessments of the displayed position of the Doppler sample volume.

Blood Flow Velocity↗

PubMedDate not supplied

Backscatter coefficient imaging using a clinical scanner.

A clinical ultrasound scanner has been integrated with a digital data acquisition system to record echo signals for off-line processing of quantitative acoustic backscatter images. The method used to determine backscatter coefficients accounts for experimental factors related to the beam directivity function, the transmitting and receiving electronics, and the attenuation path of the beam. After characterization and calibration of the ultrasound scanner according to the data processing requirements, the quantitative backscatter coefficient for tissue-mimicking phantoms are within 14% of a value predicted by scattering theory. On five normal volunteers, preliminary in vivo liver images of the acoustic backscatter coefficient are obtained. Results from this study are compared to previously published in vitro results.

Humans↗