Knowledge Bank

Surgery is the main treatment option for solid tumors. Surgeons use palpation and sight to identify and remove these malignant tumors during surgery. Surgically excised tissue are marked only at a few locations for pathological analysis so that much less than 1% of the excised tissue is actually analyzed. Analysis of all removed tissue could enable surgeons to decide in real-time whether or not more surgical intervention is necessary. The overall goals of this research are (1) to develop a tool that surgeons can use to quantify the boundaries of tumors embedded in excised tissue, and (2) to provide an objective basis for determining in real-time whether or not any additional surgical intervention is necessary while the patient is still in the operating room (OR). Recent work at OSU has shown that eddy currents induced in tissue by a time-varying magnetic field can be used to distinguish between cancer-bearing and normal tissue. The objectives of this project are to design, construct, and optimize an eddy current detector for real-time detection of malignant solid tumor boundaries. The eddy current probe comprises two coaxial coils, the inner of which is the primary and the outer serves as the detector. Inter-layer effects are explored by removing a detector coil layer from a previous probe design and the effect of the probe’s intrinsic capacitance is explored by varying the insulation thickness of the probe wires. The probes are then characterized and evaluated using measurements on animal tissue. It is found that removing a layer of windings in the detector coil sharply reduces the detector coil’s inductance and voltage signal when measuring tissue. Furthermore it is found that the intrinsic probe capacitance due to wire insulation thickness also affects the detector signal, but to a lesser extent than removing a detector coil layer. Both the number of detector coil layers and intrinsic probe capacitance affect the ability of the eddy current probe to detect tissue and determine contrast between tissue types.