Biomedical EM, Optics, and Ultrasound

This chapter discusses some key formulations in biomedical electromagnetics (EM). Extensive work has been reported on static through terahertz coupling to bodies near fields, cell phones, specific absorption rate (SAR), narrow and UWB pulse in biological systems. The chapter considers specific absorption rate (SAR) and heat diffusion in tissues. It describes the diffusion approximation of the radiative transfer theory. In the diffusion approximation, the specific intensity has a broad angular spectrum and therefore the diffused wave cannot be focused into a small volume. There is a way to focus the diffused wave, but the focusing requires constructive interference near the focal point and destructive interference elsewhere. The chapter also discusses fundamentals of ultrasound scattering and imaging of tissues and blood. Optical coherence tomography (OCT) was introduced to obtain noninvasive images of biological images of biological tissues with resolutions of 1‐15 μm.