| dc.description.abstract | Compared with conventional open surgery, High-intensity focused ultrasound (HIFU) thermal therapy is non-invasive and has no radiation and less bleeding. The main mechanism of HIFU ablation treatment involves mechanical and thermal effects, which can generate high temperature to heat and destroy target cells. Currently, HIFU has been applied in the treatment of prostate, liver, breast, and bone tumor. With the application of targeting microbubbles, tumors can be treated by heat or local higher concentration of drug activated by HIFU. However, the focus point of HIFU must be located accurately and precisely so that it can destroy target tumor cells completely.
In this study, the focus point of a HIFU system is located. After the thermocouple tip for temperature measurement is located by ultrasound scan, a robot moves the HIFU focal point along the HIFU focusing axis to heat the thermocouple tip. The position with highest temperature is defined as the true position of the HIFU focal point. The difference between the true position of the HIFU focal point and that of the thermocouple tip detected by ultrasonic image and transferred relative to the robot coordinate system is the position offset of the focus point. The experimental results show the offset is 6mm.
This study also investigates the impact of phantom shape on the focusing effect. The experimental results show that the symmetry of the phantom body was helpful to the efficiency of the acoustic focusing. Finally, the calibrated HIFU system pork tissue is applied to ablate pork tissues (muscle and fat) and the targeting microbubbles, the results show that a single tissue can be quickly heated, but the heating of multiple-layer tissues are out of prediction, which requires further study. Moreover, HIFU targeting microbubbles can be detected and destroyed easily no matter they are targeting on small spots, silicon tubes or spherical sponges.
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