Nonlinear native propagation effects of diagnostic ultrasound computed and measured in blood
| Autor: | Tamara Kujawska, B. Zienkiewicz, J. Wj́cik, G. Łypacewicz, R. Tymkiewicz, L. Filipczyśki |
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| Rok vydání: | 2001 |
| Předmět: |
medicine.medical_specialty
Materials science Acoustics and Ultrasonics Radiological and Ultrasound Technology Swine Biophysics Second-harmonic imaging microscopy Linearity Signal Processing Computer-Assisted Acoustics Mechanics Surgery Harmonic analysis Nonlinear system Blood Harmonics Pressure medicine Harmonic Animals Radiology Nuclear Medicine and imaging Ultrasonic sensor Beam (structure) Ultrasonography |
| Zdroj: | Ultrasound in Medicine & Biology. 27:251-257 |
| ISSN: | 0301-5629 |
| DOI: | 10.1016/s0301-5629(00)00329-x |
| Popis: | Nonlinear propagation effects produced by focused pulses in blood were measured over a 20-cm range, being inspired by diagnostic applications in cardiology. The initial and maximum pressures applied during measurements in blood were equal to 0.40 MPa pp and 0.76 MPa pp , while the pressure estimated at the patient body surface equalled 0.70 MPa pp . Measurements of the frequency characteristic and the linearity of the ultrasonic probe used in experiments were performed in water. A numerical procedure developed previously was applied in blood to calculate the pressure distribution of its first and second harmonics along the beam axis. The comparison of numerical and measured distributions in blood at a temperature of 37°C showed rather good agreement. Using numerical methods, a proportional growth of the second harmonic with the increased applied initial pressure was first observed, and finally the maximum limiting effect was found. In this way, much higher level of harmonics could be obtained. However, there arise the questions of the transmitting system construction and of the nonuniform resolution in the case of harmonic imaging when increasing the applied initial pressure. (E-mail: lfilipcz@ippt.gov.pl) |
| Databáze: | OpenAIRE |
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