Journal of Pure and Applied Ultrasonics

Madhusudan Roy ¹, Supratic Chakraborty ¹

Affiliations
1 Microelectronics Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata-700064, IN

Abstract

An anomaly in ultrasound attenuation of agarose hydrogel studied over a temperature range of 283 K to 311 K, is observed. Anomalous ultrasound attenuation occurs at ~290 K. A theoretical model has been worked out to explain the anomaly. A differential scanning calorimetry (DSC) study shows an endothermic peak at ~290 K, indicating phase transition when scanned over a temperature range of 282 to 330 K at different heating rates. The investigation helps identify the range of temperature over which a gelatin/agar-based phantom may be used in mimicking tissues. This effect may also be explored in temperature imaging.

Keywords

Ultrasound Attenuation, Agarose, Imonification, Pulse Echo, Time of Flight.

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Supratic Chakraborty ¹, Madhusudan Roy ¹

Affiliations
1 Microelectronics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700064, IN

Abstract

This article deals with a feasibility of imaging the temperature of a specimen of interest in a noninvasive manner by ultrasound technique. A suitable working formula has been deduced to establish as to how ultrasound attenuation of a thermally bad and viscous material changes with the temperature. An experiment on the variation of ultrasound attenuation with the temperature was carried out. Agar hydrogel, a phantom material, mimics acoustic properties of soft tissues e.g. speed and attenuation has been taken as the sample for the proposed experiment. Temperature dependence of ultrasonic attenuation of agar phantom has been suggested as a noninvasive technique for temperature imaging. The attenuation of a tissue mimicking phantom, agar was estimated over a range of temperature of 293 to 316 K for three different agar densities (2%, 3% and 4% by weight). The variation of attenuation with temperature has been found to be a monotonic one in the above range and the curve can be used as a temperature calibration for agar in this temperature range. The concept may be applicable to all the real tissues to measure any temperature rise under in vivo condition during ablation or microwave thermotherapy provided the temperature dependence of ultrasound attenuation of the tissues are known before hand. PACS No: 43.90.+v, 43.58,+z, 05.70.-a, 43.80.-n.

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