Temperature elevation in focused Gaussian ultrasonic beams at various insonation times
| Autor: | Tamara Kujawska, Janusz Wójcik, L. Filipczyński |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Materials science
Hot Temperature Time Factors Acoustics and Ultrasonics Gaussian Biophysics Models Biological Ultrasonography Prenatal Absorption symbols.namesake Thermal conductivity Optics Pregnancy Humans Radiology Nuclear Medicine and imaging Absorption (electromagnetic radiation) Ultrasonography Radiological and Ultrasound Technology business.industry Temperature Thermal Conductivity Mechanics Hyperthermia Induced Nonlinear system symbols Ultrasonic sensor Female Constant (mathematics) business Beam (structure) Mathematics Gaussian beam |
| Zdroj: | Ultrasound in medicinebiology. 19(8) |
| ISSN: | 0301-5629 |
| Popis: | Transient solution of the thermal conductivity equation for the three-dimensional case of the Gaussian ultrasonic focused beam was derived and applied for cases relevant to medical ultrasonography. Quantitative results for the case of a homogeneous medium with constant values of thermal coefficients and constant absorption as well as for the two-layer tissue model used in obstetrics were presented for various diagnostic probes used in ultrasonography. The possible effects of perfusion and nonlinear propagation were neglected. The results obtained are in agreement with results of other authors when considering the steady-state and the infinitely short insonation time. The computations show the influence of the insonation time on the temperature elevation, thus making it possible to introduce its value as a factor in limiting the possible harmful effects in ultrasonography. This has been shown in diagrams presenting the temperature distribution along the beam axis of 6 different diagnostic probes for various insonation times and demonstrating the corresponding temperature decrease when limiting the insonation time to 5 and 1 min. For instance, the highest temperature elevation (for probe number 1, see Table 1) decreases 2.6 and 5 times with respect to the steady-state temperature when the insonation time equals 5 and 1 min, respectively. |
| Databáze: | OpenAIRE |
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