volume | PIER Journals

Abstract

A high-order closed-form solution for the specific absorption rate (SAR) distribution induced inside a plane geometry fatmuscle tissue by a shortwave diathermy induction coil is presented. The solution is derived starting from the complete integral expressions for the electromagnetic field components generated by a currentcarrying circular loop located horizontally above a stratified earth. It is valid in a wide frequency range, and is flexible to any multi-turn coil configuration. The spatial distribution of the SAR induced in the muscle tissue by a flat round coil is computed by using the proposed formulation, the zero-order quasi-static one, and the finite difference time domain (FDTD) method. Excellent agreement is demonstrated to exist between the results provided by the new approach and those achieved through FDTD simulations. On the contrary, the performed computations show that the zero-order solution leads to over-estimate the SAR. The performances of the round and figure-eight coil geometries are compared. Despite of what has been argued in previously published papers, it turns out that the figure-eight coil is less energetically efficient than the round one. The work in the present paper is an extension of a previous work.

1. Hill, J., M. Lewis, P. Mills, and C. Kielty, "Pulsed shortwavediathermy effects on human fibroblast proliferation," Arch. Phys. Med. Rehabil., Vol. 83, No. 6, 832-836, 2002.
doi:10.1053/apmr.2002.32823 Google Scholar

2. Santoro, D., L. Ostrander, B. Y. Lee, and B. Cagir, "Inductive 27.12 MHz diathermy in arterial peripheral vascular disease," EMBS 1994, Proc. IEEE 16th Annual Intern. Conf., Vol. 2, 776-777, 1994. Google Scholar

3. Guy, A.W., J. F. Lehmann, and J. B. Stonebridge, "Therapeutic applications of electromagnetic power," Proceedings of the IEEE, Vol. 62, No. 1, 55-75, 1974.
doi:10.1109/PROC.1974.9385 Google Scholar

4. Rhattoy, A., S. Bri, and M. Audhuy-Peudecedery, "Coaxial antenna for microwave hyperthermia," Journal of Electromagnetic Waves and Applications, Vol. 19, No. 14, 1963-1971, 2005.
doi:10.1163/156939305775570585 Google Scholar

5. Rajhi, A., "Optimization of the EM heating cycle by using a dual frequency local hyperthermia applicator," Journal of Electromagnetic Waves and Applications, Vol. 17, No. 3, 447-464, 2003.
doi:10.1163/156939303767868946 Google Scholar

6. Wu, M. S., K. Ito, and H. F. Kasai, "Analysis of current and electric field distributions of coaxial-slot antenna for interstitial microwave hyperthermia," Journal of Electromagnetic Waves and Applications, Vol. 9, No. 5–6, 831-849, 1995.
doi:10.1163/156939395X00938 Google Scholar

7. Kerem, M. and K. Yigite, "Effects of continuous and pulsed shortwave diathermy in low back pain," The Pain Clinic, Vol. 14, No. 1, 55-59, 2002.
doi:10.1163/156856902760189188 Google Scholar

8. Sciuto, M. G., C. Zanon, A. Mussa, R. Clara, M. Bortolini, A. Malossi, R. Moscato, P. Celoria, M. De Andrea, M. Rizzo, and I. Chiapp, "Chemohyperthermia for advanced abdominal malignancies: A new procedure with closed abdomen and previously performed anastomosis," International Journal of Hyperthermia, Vol. 17, No. 5, 456-464, 2001.
doi:10.1080/02656730110068311 Google Scholar

9. Curto, S. and M. J. Ammann, "Electromagnetic coupling mechanism in a layered human tissue model as reference for 434MHz RF medical therapy applicators," Proc. 2007 IEEE Antennas and Propagation Society International Symposium, Vol. 1, 3185-3188, 2007.
doi:10.1109/APS.2007.4396213 Google Scholar

10. Ren, C., P. P. Tarjan, and D. B. Popovic, "A novel electric design for electromagnetic stimulation — The slinky coil," IEEE Trans. Biomed. Eng., Vol. 42, No. 9, 918-925, 1995.
doi:10.1109/10.412658 Google Scholar

11. Nyenhuis, J. A., G. A. Mouchawar, J. D. Bourland, and L. A. Geddes, "Energy considerations in the magnetic (Eddycurrent) stimulation of tissues," IEEE Trans. Magnetics, Vol. 27, No. 1, 680-687, 1991.
doi:10.1109/20.101117 Google Scholar

12. Esselle, K. P. and M. A. Stuchly, "Quasi-static electric field in a cylindrical volume conductor induced by external coils," IEEE Trans. Biomed. Eng., Vol. 41, No. 2, 151-158, 1994.
doi:10.1109/10.284926 Google Scholar

13. Schnabel, V. and J. J. Struijk, "Calculation of electric fields in a multiple cylindrical volume conductor induced by magnetic coils," IEEE Trans. Biomed. Eng., Vol. 48, No. 1, 78-86, 2001.
doi:10.1109/10.900251 Google Scholar

14. Singh, N. P. and T. Mogi, "Electromagnetic response of a large circular loop source on a layered earth: A new computation method," Pure and Applied Geophysics, Vol. 162, No. 1, 181-200, 2005.
doi:10.1007/s00024-004-2586-2 Google Scholar

15. Gustavsen, B. and A. Semlyen, "Rational approximation of frequency domain responses by vector fitting," IEEE Trans. Power Delivery, Vol. 14, No. 3, 1052-1061, 1999.
doi:10.1109/61.772353 Google Scholar

16. Cristina, S. and M. Parise, "Closed-form expression of the SAR distribution in a multilayered planar model for shortwave inductive diathermy ," Proc. IEEE 1st Intern. Conf. Bio. Medical Engineering & Informatics, Vol. 2, 577-582, 2008.
doi:10.1109/BMEI.2008.221 Google Scholar

17. Guptasarma, D. and B. Singh, "New digital linear filters fo Hankel J0 and J1 transforms," Geophysical Prospecting, Vol. 45, No. 5, 745-762, 1997.
doi:10.1046/j.1365-2478.1997.500292.x Google Scholar

18. Kong, F. N., "Hankel transform filters for dipole antenna radiation in a conductive medium," Geophysical Prospecting, Vol. 55, No. 1, 83-89, 2007.
doi:10.1111/j.1365-2478.2006.00585.x Google Scholar

19. Felsen, L. B. and N. Marcuvitz, Radiation and Scattering of Waves, IEEE Press, Piscataway, NJ, 1994.

20. Marsden, J. E. and M. J. Hoffman, Basic Complex Analysis, W. H. Freeman and Company, New York, 1998.

21. "Tissue dielectric properties,", Federal Communications Commission, Washington, DC [Online], http://www.fcc.gov/fccbin/dielec.sh. Google Scholar

Dr. Mauro Parise

Prof. Saverio Cristina