Fundamentals of Magnetic Resonance Imaging

Abstract

All the materials and living objects around us are composed of atoms. Atoms consist of three main particles that are positively charged protons, negatively charged electrons, and neutrons without any charge. The protons and neutrons are located within the nucleus of the atoms and electrons are located outside the nucleus as shown in Fig. 2.1a. The elements in the nature have additional properties called atomic weight and atomic number. Atomic number is simply the number of protons in the nucleus. Atomic weight is the sum of protons and neutrons in the nucleus. The most abundant atom in the human body is the hydrogen atom and it has the same atomic number and atomic weight, which is equal to one. All atoms can have the same atomic number. However, they can have different atomic weights (different number of neutrons) and those are called isotopes.