a review of ultrasound thermometry techniques

Acoustic thermometry is one of non-invasive methods to measure the temperature inside tissue area. especially, when using the thermal therapy techniques such as high intensity focused ultrasound (hifu) and other thermal based methods, thermal assessment of heated area seems to be necessary. some of acoustic properties of medium are temperature dependent; therefore, evaluation of temperature dependent parameters will be an indirect and non-invasive approach in thermometry. in this paper some of thermometry methods based on changes in acoustic properties of medium have been reviewed. the published methods are classified in two main categories: passive and active thermometry. in the passive thermometry, the thermal measurement probes, induced no acoustic signals to the medium, but they receive the radiated signals from the heated medium. in active method, the thermometry probe transmits a signal into the heated region and receives the echoes, then the received rf signals are processed in order to measure the temperature.