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Proceedings Paper

Stable microwave radiometry system for long term monitoring of deep tissue temperature
Author(s): Paul R. Stauffer; Dario B. Rodriques; Sara Salahi; Erdem Topsakal; Tiago R. Oliveira; Aniruddh Prakash; Fabio D’Isidoro; Douglas Reudink; Brent W. Snow; Paolo F. Maccarini
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Paper Abstract

Background: There are numerous clinical applications for non-invasive monitoring of deep tissue temperature. We present the design and experimental performance of a miniature radiometric thermometry system for measuring volume average temperature of tissue regions located up to 5cm deep in the body. Methods: We constructed a miniature sensor consisting of EMI-shielded log spiral microstrip antenna with high gain onaxis and integrated high-sensitivity 1.35GHz total power radiometer with 500 MHz bandwidth. We tested performance of the radiometry system in both simulated and experimental multilayer phantom models of several intended clinical measurement sites: i) brown adipose tissue (BAT) depots within 2cm of the skin surface, ii) 3-5cm deep kidney, and iii) human brain underlying intact scalp and skull. The physical models included layers of circulating tissue-mimicking liquids controlled at different temperatures to characterize our ability to quantify small changes in target temperature at depth under normothermic surface tissues. Results: We report SAR patterns that characterize the sense region of a 2.6cm diameter receive antenna, and radiometric power measurements as a function of deep tissue temperature that quantify radiometer sensitivity. The data demonstrate: i) our ability to accurately track temperature rise in realistic tissue targets such as urine refluxed from prewarmed bladder into kidney, and 10°C drop in brain temperature underlying normothermic scalp and skull, and ii) long term accuracy and stability of +0.4°C over 4.5 hours as needed for monitoring core body temperature over extended surgery or monitoring effects of brown fat metabolism over an extended sleep/wake cycle. Conclusions: A non-invasive sensor consisting of 2.6cm diameter receive antenna and integral 1.35GHz total power radiometer has demonstrated sufficient sensitivity to track clinically significant changes in temperature of deep tissue targets underlying normothermic surface tissues for clinical applications like the detection of vesicoureteral reflux, and long term monitoring of brown fat metabolism or brain core temperature during extended surgery.

Paper Details

Date Published: 26 February 2013
PDF: 11 pages
Proc. SPIE 8584, Energy-based Treatment of Tissue and Assessment VII, 85840R (26 February 2013); doi: 10.1117/12.2003976
Show Author Affiliations
Paul R. Stauffer, Duke Univ. (United States)
Dario B. Rodriques, Duke Univ. (United States)
Sara Salahi, Duke Univ. (United States)
Erdem Topsakal, Mississippi State Univ. (United States)
Tiago R. Oliveira, Duke Univ. (United States)
Aniruddh Prakash, Duke Univ. (United States)
Fabio D’Isidoro, Duke Univ. (United States)
Douglas Reudink, Thermimage Corp. (United States)
Brent W. Snow, Thermimage Corp. (United States)
Paolo F. Maccarini, Duke Univ. (United States)

Published in SPIE Proceedings Vol. 8584:
Energy-based Treatment of Tissue and Assessment VII
Thomas P. Ryan, Editor(s)

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