Ultrasound thermometry for optimizing heat supply during a hyperthermia therapy of cancer tissue

摘要

Monitoring the temperature during a hyperthermia therapy allows optimizing the heat supply to destroy the cancer whereby the damage in the surrounding tissue is minimized. This contribution presents the fundamental research and current work to realize a locally resolved, noninvasive and intra-surgically applicable temperature measurement in tissue. This is realized by measuring the sound velocity locally resolved by an annular array, which allows noninvasive measurements although the observed tissue is not accessible from all directions. The method had been already qualified for fluids and analyses the echoes of moving scattering particles to obtain the time of flight to the focus of the transducer. As the parameters of the transducer are known the focus position (and thus the time of flight) can be calculated as a function of the sound velocity distribution of the propagation medium. Hence the measured time of flight allows determining the focus position and mean sound velocity simultaneously by means of this function. Varying the time lags of the signals for each element allows moving the focus and so measuring locally resolved. This contribution presents first ex-vivo measurements in tissue and thus proves the adaptability of this technique for tissue.