A new method for targeted heating of deep tissue was developed by using an ultrasound phased-arraysystem which can generate various multiple foci patterns by electronically changing its amplitude or phasepattern.This method involves using a technique of combining switching and rotating of multiple foci pat-terns to create a uniform temperature over tissue volumes in various size.Using this method,the targettissue deep in the body can be heated to a specified temperature,which gives conditions for thermo-sensi-tire liposomes release.A simulation study for a 108-element,spherically sectioned array was performed todetermine an optimal heating scheme from a set of multiple focus fields which were produced by inputtingdifferent combinations of phases and amplitudes.Comparisons of a static multiple foci field,the switchedfields and the switched-rotated fields indicated that the technique of combining switching and rotating ofmultiple foci patterns has advantages of both lowering the peak temperature and evening the temperaturedistribution.The simulation results also show that the therapeutic heating zones in various size(φ5mm～φ40mm)with uniform temperature distributions can be obtained employing the combined method.Theseresults offer significant data for designing thermotherapy equipment for tumor-specific drug release withthermo-sensitive hposomes.
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