Electromagnetic optimization of dual-mode antennas for radiometry-controlled heating of superficial tissue

The large variance of survival in the treatment of large superficial tumors indicates that the efficacy of current therapies can be dramatically improved. Hyperthermia has shown significant enhancement of response when used in combination with chemotherapy and/or radiation. Control of temperature is a critical factor for treatment quality (and thus effectiveness), since the response of tumor and normal cells is significantly different over a range of just a few degrees (41-45°). For diffuse spreading tumors, microwave conformal arrays have been shown to be a sound solution to deposit the power necessary to reach the goal temperature throughout the targeted tissue. Continuous temperature monitoring is required for feedback control of power to compensate for physiologic (e.g. blood perfusion and dielectric properties) changes. Microwave radiometric thermometry has been proposed to complement individual fluoroptic probes to non-invasively map superficial and sub-surface temperatures. The challenge is to integrate the broadband antenna used for radiometric sensing with the high power antenna used for power deposition. A modified version of the dual concentric conductor antenna presented previously is optimized for such use. Several design challenges are presented including preventing unwanted radiating modes and thermal and electromagnetic coupling between the two antennas, and accommodating dielectric changes of the target tissue. Advanced 3D and planar 2D simulation software are used to achieve an initial optimized design, focused on maintaining appropriate radiation efficiency and pattern for both heating and radiometry antennas. A cutting edge automated measurement system has been realized to characterize the antennas in a tissue equivalent material and to confirm the simulation results. Finally, the guidelines for further development and improvement of this initial design are presented together with a preliminary implementation of the feedback program to be used to control the temperature distribution in variable, inhomogeneous tissue.

[1]  Paul R. Stauffer,et al.  Multifrequency radiometric determination of temperature profiles in a lossy homogeneous phantom using a dual-mode antenna with integral water bolus , 2002 .

[2]  R. Taschereau,et al.  Combination applicator for simultaneous heat and radiation , 2004, The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[3]  Piero Tognolatti,et al.  Temperature Reconstructions in a Dielectric Cylinder by Multi-Frequency Microwave Radiometry , 1993 .

[4]  J. Schlorff,et al.  Construction of a Conformal Water Bolus Vest Applicator for Hyperthermia Treatment of Superficial Skin Cancer , 2004, The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[5]  P R Stauffer,et al.  Thermal and SAR characterization of multielement dual concentric conductor microwave applicators for hyperthermia, a theoretical investigation. , 2000, Medical physics.

[6]  Kai Chang,et al.  Multifrequency operation of microstrip-fed slot-ring antennas on thin low-dielectric permittivity substrates , 2002 .

[7]  Paul R. Stauffer,et al.  Transceiving antenna for homogeneous heating and radiometric thermometry during hyperthermia , 2000 .

[8]  M. Laberge.  [Cancer of the breast]. , 1961, Laval medical.

[9]  S. Mizushina,et al.  Non-invasive thermometry with multi-frequency microwave radiometry. , 1992, Frontiers of medical and biological engineering : the international journal of the Japan Society of Medical Electronics and Biological Engineering.

[10]  P. Staufer,et al.  Effect of complex bolus-tissue load configurations on SAR distributions from dual concentric conductor applicators , 1999, IEEE Transactions on Biomedical Engineering.

[11]  D. Kapp,et al.  Efficacy of adjuvant hyperthermia in the treatment of superficial recurrent breast cancer: confirmation and future directions. , 1996, International journal of radiation oncology, biology, physics.

[12]  E. Cardan,et al.  Hyperthermia , 1983 .

[13]  P R Stauffer,et al.  Theoretical characterization of dual concentric conductor microwave applicators for hyperthermia at 433 MHz. , 2001, International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group.

[14]  Chris J. Diederich,et al.  Microwave vest for hyperthermia treatment of large area superficial disease , 1999, Proceedings of the First Joint BMES/EMBS Conference. 1999 IEEE Engineering in Medicine and Biology 21st Annual Conference and the 1999 Annual Fall Meeting of the Biomedical Engineering Society (Cat. N.

[15]  Titania Juang,et al.  Progress on system for applying simultaneous heat and brachytherapy to large-area surface disease (Invited Paper) , 2005, SPIE BiOS.

[16]  P R Stauffer,et al.  Effect of practical layered dielectric loads on SAR patterns from dual concentric conductor microstrip antennas. , 1998, International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group.

[17]  G. Fletcher,et al.  Frequency, anatomical distribution and management of local recurrences after definitive therapy for breast cancer , 1966, Cancer.

[18]  W. Donegan,et al.  A biostatistical study of locally recurrent breast carcinoma. , 1966, Surgery, gynecology & obstetrics.

[19]  P Stauffer,et al.  Non-invasive temperature profile estimation in a lossy medium based on multi-band radiometric signals sensed by a microwave dual-purpose body-contacting antenna , 2002, International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group.

[20]  D. Kapp,et al.  Breast cancer: chest wall hyperthermia-electron beam therapy. , 1991, Frontiers of radiation therapy and oncology.

[21]  Paul R. Stauffer,et al.  Microwave array applicator for radiometry-controlled superficial hyperthermia , 2001, SPIE BiOS.

[22]  Jean Pouliot,et al.  Radiation Dosimetry of a Conformal Heat-brachytherapy Applicator , 2004, Technology in cancer research & treatment.

[23]  Svein K. Jacobsen,et al.  Dual-mode antenna design for microwave heating and noninvasive thermometry of superficial tissue disease , 2000, IEEE Transactions on Biomedical Engineering.

[24]  P. Stauffer,et al.  Radiation patterns of dual concentric conductor microstrip antennas for superficial hyperthermia , 1998, IEEE Transactions on Biomedical Engineering.

[25]  O. Mella,et al.  Enhanced effect of combined hyperthermia and chemotherapy (bleomycin, BCNU) in a neurogenic rat tumour (BT4A) in vivo. , 1982, Anticancer research.

[26]  Constantine A. Balanis,et al.  Antenna Theory: Analysis and Design , 1982 .

[27]  Paul R. Stauffer,et al.  Progress toward radiometry controlled conformal microwave array hyperthermia applicator , 2000, Proceedings of the 22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (Cat. No.00CH37143).

[28]  D Machin,et al.  Radiotherapy with or without hyperthermia in the treatment of superficial localized breast cancer: results from five randomized controlled trials. International Collaborative Hyperthermia Group. , 1996, International journal of radiation oncology, biology, physics.

[29]  B. Schem,et al.  Status of clinical hyperthermia. , 1999, Acta oncologica.

[30]  Marie E. Taylor.  Breast cancer: Chest wall recurrences , 2002, Current treatment options in oncology.

[31]  J. Overgaard.  The current and potential role of hyperthermia in radiotherapy. , 1989, International journal of radiation oncology, biology, physics.

[32]  Chris J. Diederich,et al.  Dual Concentric Conductor Radiator for Microwave Hyperthermia with Improved Field Uniformity to Periphery of Aperture , 1995 .