A. Nurouzi - M.Sc. in Medical Physics, Tehran University of Medical Sciences, Tehran, Iran.
M. J. Abolhasani - Assistant Professor, Physics and Biomedical Engineering Dept., Tehran University of Medical Sciences, Tehran, Iran. Research Center for Science & Technology in Medicine, Imam Khomeini Hospital, Tehran, Iran.
A. Takavar - Professor, Physics and Biomedical Engineering Dept., Tehran University of Medical Sciences, Tehran, Iran.
M. A. Oghabian - Assistant Professor, Physics and Biomedical Engineering Dept., Tehran University of Medical Sciences, Tehran, Iran. Research Center for Science & Technology in Medicine, Imam Khomeini Hospital, Tehran, Iran.

Introduction:  The  success  of  hyperthermia  depends  on  the  accuracy  of  the  temperature  monitoring in the tumor and the surrounding normal tissue. In this study, the temperature changes  were determined by computing the speckle displacement in the ultrasound digital images. Speckle  tracking algorithm was used to compute the displacement.  Materials and Methods: The experiment was performed on Tissue Mimicking (TM) phantoms.  The imaging probe used was a commercial type linear array operating at 10 MHz. The speckle  displacement  along  the  axial  direction  was  computed  using  Speckle  Tracking  method  and  the  temperature  changes  were  obtained  from  the  displacement  data.  Additionally,  the  temperature  changes during the heating were invasively measured by NTC thermistors. The results of the two  methods were compared against each other.   Results:  There  was  a  good  agreement  between  the  Ultrasonic  temperature  estimation  and  the  measurements made by the thermistors. The maximum error and the standard deviation obtained  were 0.53 and 0.2°C, respectively.   Discussion  and  Conclusion:  Speckle  tracking  algorithm  is  capable  of  extracting  motion  information from both the ultrasounic digital images and radiofrequency (RF) echo signals. The  temperature changes can be obtained from the displacement data. 

Ultrasound, Speed of sound, Speckle tracking, Cross-correlation, Temperature Monitoring