SAR distributions for 915 MHz interstitial microwave antennas used in hyperthermia for cancer therapy
Many research centers are investigating interstitial microwave antenna array hyperthermia (IMAAH) systems as a treatment modality for tumors at various sites. This paper presents theoretical and experimental specific absorption rate (SAR< W/kg) distributions for single insulated antennas operating at 915 MHz in muscle phantom; SAR is deduced from measured temperature rise. These coaxial antennas were typically 1-2 mm in diameter and 5-10 cm in length. Results show that dipoles with lengths much shorter than their resonant length have a characteristically large reactive input impedance component and a substantially smaller absolute SAR magnitude than resonant dipoles. Over the range of dimensions studied, the thickness of the catheter wall has little effect on the SAR distribution. All cases investigated demonstrate that the maximum SAR occurs near the junction regardless of insertion depth. Furthermore, the insertion depth has little effect on the radial SAR distribution or the distribution near the antenna tip. If the length of the tip section is shorter than resonant length, the radial SAR pattern decreases. As predicted by theory, experimental results show that an antenna with the tip section equal to a quarter-wave-length and the insertion depth equal to a half-wavelength achieves a substantial increase in the longitudinal power distribution compared to other antenna designs that were evaluated.
- OSTI ID:
- 5262641
- Journal Information:
- IEEE (Institute of Electrical and Electronics Engineers) Transactions on Bio-Medical Engineering; (USA), Vol. 35:10; ISSN 0018-9294
- Country of Publication:
- United States
- Language:
- English
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