Vesicoureteral Reflux in Children: A Phantom Study of Microwave Heating and Radiometric Thermometry of Pediatric Bladder

• Published in: IEEE transactions on biomedical engineering Vol. 58; no. 11; pp. 3269 - 3278
• Main Authors: Birkelund, Yngve, Klemetsen, Øystein, Jacobsen, Svein K., Arunachalam, Kavitha, Maccarini, Paolo, Stauffer, Paul R.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.11.2011; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Absorption; Adipose Tissue - physiology; Antennas; Biological and medical sciences; Bladder; Child, Preschool; Computer Simulation; Electromagnetic heating; Heating; Humans; Hyperthermia; Hyperthermia, Induced - instrumentation; Hyperthermia, Induced - methods; Infant; Mathematical models; Medical; Medical sciences; microwave antennas; microwave heating; Microwave radiometry; Microwaves; Models, Biological; Muscles; Muscles - physiology; Nephrology. Urinary tract diseases; Phantoms; Phantoms, Imaging; Radiometry; Radiometry - instrumentation; Radiometry - methods; Temperature; tissue-equivalent phantom; Urinary Bladder - physiology; Urinary system involvement in other diseases. Miscellaneous; Urinary tract. Prostate gland; Urine; Vesico-Ureteral Reflux - diagnosis; vesicoureteral reflux; Human; Urinary system disease; microwave antennas; Urinary tract disease; Microwave heating; Temperature measurement; Urinary system; Urinary bladder; Vesicoureteral reflux; tissue-equivalent phantom; Microwave antenna; Tissue equivalent; Radiometry; Bladder disease; Child; Hyperthermia; Induced hyperthermia; Biomedical engineering; Test object
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2011.2167148

We have investigated the use of microwave heating and radiometry to safely heat urine inside a pediatric bladder. The medical application for this research is to create a safe and reliable method to detect vesicoureteral reflux, a pediatric disorder, where urine flow is reversed and flows from the bladder back up into the kidney. Using fat and muscle tissue models, we have performed both experimental and numerical simulations of a pediatric bladder model using planar dual concentric conductor microstrip antennas at 915 MHz for microwave heating. A planar elliptical antenna connected to a 500 MHz bandwidth microwave radiometer centered at 3.5 GHz was used for noninvasive temperature measurement inside tissue. Temperatures were measured in the phantom models at points during the experiment with implanted fiberoptic sensors, and 2-D distributions in cut planes at depth in the phantom with an infrared camera at the end of the experiment. Cycling between 20 s with 20 Watts power for heating, and 10 s without power to allow for undisturbed microwave radiometry measurements, the experimental results show that the target tissue temperature inside the phantom increases fast and that the radiometer provides useful measurements of spatially averaged temperature of the illuminated volume. The presented numerical and experimental results show excellent concordance, which confirms that the proposed system for microwave heating and radiometry is applicable for safe and reliable heating of pediatric bladder.