Temperature Fields in Soft Tissue during LPUS Treatment: Numerical Prediction and Experiment Results
- Ultrasound Department, Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawinskiego 5b, 02-106 Warsaw (Poland)
Recent research has shown that beneficial therapeutic effects in soft tissues can be induced by the low power ultrasound (LPUS). For example, increasing of cells immunity to stress (among others thermal stress) can be obtained through the enhanced heat shock proteins (Hsp) expression induced by the low intensity ultrasound. The possibility to control the Hsp expression enhancement in soft tissues in vivo stimulated by ultrasound can be the potential new therapeutic approach to the neurodegenerative diseases which utilizes the known feature of cells to increase their immunity to stresses through the Hsp expression enhancement. The controlling of the Hsp expression enhancement by adjusting of exposure level to ultrasound energy would allow to evaluate and optimize the ultrasound-mediated treatment efficiency. Ultrasonic regimes are controlled by adjusting the pulsed ultrasound waves intensity, frequency, duration, duty cycle and exposure time. Our objective was to develop the numerical model capable of predicting in space and time temperature fields induced by a circular focused transducer generating tone bursts in multilayer nonlinear attenuating media and to compare the numerically calculated results with the experimental data in vitro. The acoustic pressure field in multilayer biological media was calculated using our original numerical solver. For prediction of temperature fields the Pennes' bio-heat transfer equation was employed. Temperature field measurements in vitro were carried out in a fresh rat liver using the 15 mm diameter, 25 mm focal length and 2 MHz central frequency transducer generating tone bursts with the spatial peak temporal average acoustic intensity varied between 0.325 and 1.95 W/cm{sup 2}, duration varied from 20 to 500 cycles at the same 20% duty cycle and the exposure time varied up to 20 minutes. The measurement data were compared with numerical simulation results obtained under experimental boundary conditions. Good agreement between the theoretical and measurement results for all cases considered has verified the validity and accuracy of our numerical model. Quantitative analysis of the obtained results enabled to find how the ultrasound-induced temperature rises in the rat liver could be controlled by adjusting the source parameters and exposure time.
- OSTI ID:
- 21371088
- Journal Information:
- AIP Conference Proceedings, Vol. 1215, Issue 1; Conference: ISTU-2009: 9. international symposium on therapeutic ultrasound, Aix-en-Provence (France), 24-26 Sep 2009; Other Information: DOI: 10.1063/1.3367179; (c) 2010 American Institute of Physics; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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COMPARATIVE EVALUATIONS
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EFFICIENCY
ELECTRON MICROSCOPY
HEAT TRANSFER
HEAT-SHOCK PROTEINS
IN VITRO
IN VIVO
LIVER
MHZ RANGE
NERVOUS SYSTEM DISEASES
PULSED IRRADIATION
RATS
THERAPY
THERMAL STRESSES
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EVALUATION
FREQUENCY RANGE
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ORGANIC COMPOUNDS
ORGANS
PROTEINS
RODENTS
SIMULATION
SOUND WAVES
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VERTEBRATES