Advances in Microwave Hyperthermia Treatment using Time Reversal
Doktorsavhandling, 2010

The last twenty years have seen many clinical studies showing the ability of hyperthermia to remarkably enhance response to radiation therapy and chemotherapy. The objective of hyperthermia treatment is to raise the temperature in tumors to therapeutic levels, for a sufficient period of time, in order to achieve cell death or render the cells more sensitive to ionizing radiation and/or chemotherapy. One of the challenges in hyperthermia is to adequately heat deep-seated tumors while preventing surrounding healthy tissue from undesired heating and damage. In this thesis, a new focusing technique, based on a time-reversal (TR) approach, for microwave hyperthermia is described and evaluated. First, the method was tested numerically using 2-D computer models of breast and neck. The obtained results were encouraging and suggest a multifrequency approach, in which the choice of frequency depends on the treated area size as well as on the tumor volume. Building on these results, a specific broadband antenna array was designed. In this design the applicator is immersed in a matching liquid and consists of between 12 and 16 identical triangular patch elements placed in a ring antenna arrangement. Next, we built a TR-hyperthermia amplifier system that operates in both continuous and pulsed wave regimes. The accuracy of the signal delivery as prescribed by the treatment planning tool is similar to clinical standards. However, at present, the output power allows only for experiments with phantoms or animals. The results show great promise and will be further investigated in clinical studies. Finally, the feasibility of microwave thermal imaging as a non-invasive approach for temperature monitoring during the treatment was investigated. The initial results of this approach, which is based on the variation of the dielectric properties with temperature, are encouraging. Work is in progress to evaluate the prospects of integrating microwave thermometry into our TR-hyperthermia system.

microwave hyperthermia

time reversal

microwave thermometry

annular phased array

amplifier system

treatment planning

HA3, Hörsalsvägen 4, Chalmers University of Technology
Opponent: Dr. Gerald van Rhoon PhD, Dept. Radiation Oncology, Erasmus MC ­ Daniel den Hoed Cancer Center, The Netherlands

Författare

Hana Dobsicek Trefna

Chalmers, Signaler och system, Signalbehandling och medicinsk teknik, Biomedicinsk elektromagnetik

Time-reversal focusing in microwave hyperthermia for deep-seated tumors

Physics in Medicine and Biology,; Vol. 55(2010)p. 2167-2185

Artikel i vetenskaplig tidskrift

Evaluation of a patch antenna applicator for time reversal hyperthemia

International Journal of Hyperthermia,; Vol. 26(2010)p. 185-197

Artikel i vetenskaplig tidskrift

Ämneskategorier

Medicinsk laboratorie- och mätteknik

ISBN

978-91-7385-305-7

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 3092

HA3, Hörsalsvägen 4, Chalmers University of Technology

Opponent: Dr. Gerald van Rhoon PhD, Dept. Radiation Oncology, Erasmus MC ­ Daniel den Hoed Cancer Center, The Netherlands