Study On Electromagnetic Problems Of The Magnetic Stereotaxis System

The Magnetic Stereotaxis System (MSS) is a unique less-invasive interventional operation device that is designed to deliver a small permanent pellet and an attached catheter directly into the vasculatures or soft tissues of a patient to perform complicated surgical operations under the control of spatial magnetic field distributions. After carefully studied on the recent development of the MSS, this paper mainly concerned on the basic theories and control strategies of the MSS. According to the key research problems of this thesis and the disadvantages of the current MSS, this paper presents a novel type of superconducting magnet structure. The first domestic model MSS has also been constructed and a series of experiments have been performed to simulate the real operation situations on this base. The main research aspects are as follows: In theory, this paper developed Turner's target fields approach in the design of spherical coils. This approach allows the modeling of particular linear gradient magnetic fields inside the spherical volumes. Based on the practical constructions in engineering, this paper optimized the original spherical magnet scheme and presented a type of modified quadrupole spherical magnet structure. After carefully theoretical analysis and FEA software simulations, this new type of coils can generate nearly linear gradient fields inside the spherical volumes. In addition, compared with the traditional solenoid coils of the similar dimensions and current values, the spherical coils can generate higher fields while the inductance values keep lower, which is essential for the MSS. In addition, this paper also studied the magnetic force relationships between the quasi-static magnetic fields and small permanent pellets. This paper also analytically calculated the field distributions and magnetic forces in multi-spherical coils situations. From the practical motion patterns of the small pellet, this paper also studied the approaches of friction measurements in gelatin phantom material and the preliminary calculation formulas of the current-displace relationships during the...