The Development Of A Gantry System For High Intensity Focused Ultrasound

High Intensity Focused Ultrasound (HIFU) is one of the promising results innon-invasive thermal ablation techniques of tumor in recent years. It can be used forthe treatment of benign and malignant tumors. Since ultrasound can penetrate into oftissues，HIFU is a method of focusing ultrasound waves(intensity of hundreds orthousands W/cm2) on a particular area, inducing sharp increase in temperature(above65oC). This heat can be used to crate lesions and tissue death due tocoagulative necrosis and the surrounding tissues do not damaged.HIFU treatment system is a complicated system which gathers togetherfocalization, orientation, imaging and control. The orientation system is the crosstheoretic of ultrasonics and robotology. This thesis gave a brief introduction of thesystem s treatment principle and process, carried out a detailed analysis of several keytechnologies and system.This thesis presents a new kind of HIFU therapy system model. Simplify themodel, according to the current laboratory needs, this thesis design and manufacturea HIFU moving mechanism for experimental research. For the shortcomings of thecurrent domestic and international HIFU system control, the control structure of thesystem is improved, this thesis use lower machine control subsystems to assist PC tomanage the system.For self-focused ultrasound treatment system, accurate, real-time control of thetrajectory and speed of the transducer is crucial. Based on the first-order-Taylorseries interpolation algorithm, the actual "linear velocity" concept is proposed, andthe linear velocity error is improved for any kind of movement along parametriccurves. The new control methods can also effectively maintain the step-size shift andchord deviation within the permitted range. The experiments show that the stabilityof the linear velocity has been also verified and it can also effectively maintain thestep-size shift and chord deviation within the permitted range..In this thesis，both designed the lower machine controller software and PCcontrol software, and to develop a detailed communication control protocol betweenthe upper and lower computer. Transplanted μc/os-II real-time operating system inlower machine controller, and create four parallel user tasks. Lower machinecontroller display the basic information of the moving mechanism and coarsepositioning by touching the screen. Receiving moving data transfer from PC GUIand control the mechanical movement; PC GUI, as the main human interface, set motor parameter and calculate the trajectory moving data. The host computers fullyconsider the various parameters of movement and composition, has a good userinterface, and can display trajectory parameters information. It can maintain thehistorical data conveniently. Users can better carry out the treatment plan.Experiments show that the HIFU moving mechanism designed in this paper canmeet the requirements of the experimental study and laid a foundation for furtherstudy.