טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentDikla Zisman
SubjectStudy of Ultrasound Hyprerthermia Therapy and its Control
by Ultrasound Imaging
DepartmentDepartment of Biomedical Engineering
Supervisor Professor Emeritus Adam Dan


Abstract

The hallmark of acoustic therapy is its ability to induce biological effects deep within the body without surgical intervention. Non-invasive treatment by HIFU (High Intensity Focused Ultrasound) has been demonstrated as an optional method of treatment when cells injury in required for tumor destruction. Since the destruction of the tissue in thermal treatment is irreversible real time monitoring is necessary.

The main goal of this study was to investigate whether the generation of localized hyperthermia, by HIFU for ablation or coagulation of tissue, could be optimized by: a) Combination of three different transducers aiming at the same focus point. b) A two-stage process that includes a stage of bubbles creation by cavitation and a stage of thermal heating.

Another goal of this study was to investigate the possibility to use ultrasound to control the location of the thermal damage by analyzing the location of the bubbles.

In vitro experiments were preformed in water, in a gel phantom that simulates a lesion and in a pig’s liver. Synchronization between the ultrasound imaging system -VIVID3 (GE Medical System) and the three transducers for thermal heating enabled monitoring of the treatment in real time.

The results demonstrated that the 2-stage procedure enables to visualize the location of the production of bubbles and to decide whether to continue with the treatment, or to change its location (since only cavitation causes a non-significant temperature raise). A significant temperature rise was obtained after a few seconds of cavitation (30sec). Non-significant temperature elevation was obtained when the cavitation stage was eliminated. Thus a proof of concept of this treatment method and its control has been achieved.