UWB Microwave Brain Imaging For Stroke Detection

"Stroke" is known as "cerebral vascular accident",which is one sort of disease caused by either the sudden rupture of cerebral blood vessels or vascular obstruction.Currently,physicians mainly rely on computed tomography(CT)and magnetic resonance imaging(MRI)for the confirmation of the diagnosis.The complexity of stroke diagnosis emphasizes the vital importance played by the CT and MRI scan systems.They are however,not fast,cost effective or portable,nor are they accessible at rural medical clinics,or carried by first response paramedical teams.Potentially,UWB(Ultra Wideband)electromagnetic wave imaging can supplement current diagnostic methods as it may potentially provide a fast,cost effective and portable detection system.In this paper,UWB electromagnetic wave imaging method is applied for stroke detection.We probe the brain by exposing tissues to low-levels of electromagnetic energy at microwave frequencies and capturing the different scattered electromagnetic energy from different tissues.Those different echoes' intensity distribution is used to image the brain.The work we have done is listed as follows:1.A 2D slice from brain phantom is used in this paper because 2D models are more computationally efficient than 3D models.In the simulation process,the finite difference time domain(FDTD)method is used to simulate and calculate the electromagnetic field by using the absorbing boundary of the perfectly matched layer(PML).2.The reflection intensity from the brain surface is quite strong because of the big dielectric property contrast between the free space and the skin,which may cause the echo from stroke will be buried by the one from surface.It is necessary to eliminate the surface reflection for accurate internal imaging.In this paper,Envelope method is newly proposed to estimate the boundary so as to suppress the surface clutter.Envelope method is a high-precision dielectric boundary estimation method in the situation where the distances from antennas to brain surface are not a constant.Moreover,delay and sum(DAS)processing is applied in this paper for compensating the propagating path distortion.3.At the end of the paper,the simulation results of the UWB electromagnetic wave brain imaging for stroke detection are provided which show that the UWB electromagnetic wave imaging method can effectively detect the stroke.The results before surface clutter suppression and after surface clutter suppression are compared which shows the necessity and high precision of the Envelope method.