Steady Fields of the Body

Abstract

Steady magnetic fields of the human body are produced in two ways: by steady currents in the body, and by magnetic material in the body. We here deal with fields produced only by steady currents; fields produced by material with a remanent moment (in the lungs and other organs) will be described in Chapters 14 and 15. We define “steady” to mean fields which change slower than 0.01 Hz. The expressions “steady” and “dc” are used interchangeably, and abbreviations involving these expressions will usually be used. These have been previously defined (Cohen et al. 1979), and are: dcF (previously dcMF) for dc or steady magnetic field, dcP for dc potential, and dcI for dc current. The dcF is produced by the dcI generated by various organs in the body, and in this chapter we consider the dcF generated by any organ except the heart. The dcF from the heart, and some aspects of the dcF from organs which can mask it, were considered in Chapter 9.5.