Dr. Bog Jarosz

Research Summary

Ultrasound waveguide interstitial applicator arrays have been studied for use in thermal therapy. The advantage of the arrays relates to minimal invasiveness of the proposed technology. Our former collaboration with a neurosurgeon led us to limit the investigation to three- or four-applicator array. To characterize the array, we examine temperature pattern in tissue phantom and in animal 
tissues. 3-D FEA modeling is used also to evaluate power required from individual applicators. The modelling is intended for planning of the array geometry that result in conformal heating with minimal heat toxicity.

Thermal effects in tissues are defined by three main factors: array geometry; blood vessels cooling; and applicator's proximity to external boundary at ambient temperature. As the array geometry and the organ of interest lack simple symmetry, we use 3-D FEA computations of temperature patterns with realistically shaped organ. We chose to model heating effects in human brain. In computations, a hybrid approach using effective thermal conductivity and bio-heat transfer equation has been used. Discrete blood vessels of differentiated physical properties have been included in the most sensitive areas. In the computations, vessels' shape and size, their location with respect to an applicator, their number and blood flow velocity have been studied. We verify our computations in tissue phantoms. Current effort is to build a head phantom including mimicked 
blood flow.

Publications/Presentations

1. Jarosz BJ. Measurement of safe thermal therapy levels: the case of ultrasonic waveguide interstitial applicator array. Conf Proc IEEE Eng Med Biol Soc. 2006;1:5025-8.
2. B. J. Jarosz and S. St.James, "Integrated Temperature Sensor for Determination of 
   Ultrasound Interstitial Applicator Heating Effects ", IEEE Trans. Instrum. Meas., 54, 1171-1174 (2005).
3. B. J. Jarosz, "Effects of External Temperature on Therapeutic Heating with 
   Interstitial Instrumentation", Proceedings, 22nd IEEE Instrumentation and Measurement Technology Conference, 17-19 May 2005, Ottawa, Canada, 384-8, (2005).
4. B. J. Jarosz, "Control of Heating Pattern from Interstitial Instrumentation", Proceedings, 21th IEEE Instrumentation and Measurement Technology Conference, 18-20 May 2004, Como, Italy, 1563-8 (2004).
5. B. Jarosz, “Thermal dose control by configuration of ultrasonic interstitial applicator array”, Scientific Program & Abstracts, 9th Int. Congr. Hyperthermic Onc., April 20-24, St. Louis, MO (2004).