1.16 Trapezoidal gradient pulse.Figure 1.17 Transmit 8‐rung ‘birdcage’ coil to produce a circularly polarise...Figure 1.18 IEC 60601‐2‐33 [4] compliant coil labelling: left‐ transmit only...Figure 1.19 Parallel transmit: two (or more) independent RF power amplifiers...Figure 1.20 Receive coil and pre‐amplifier: (a) the coil has inductance L an...Figure 1.21 Relative magnitude of magnetic fields used in MRI.Figure 1.22 Definition of the SI unit tesla.Figure 1.23 Magnetic field lines of force: (a) seen in the pattern of iron f...Figure 1.24 Fringe field contours at 0.5, 1, 3, 5, 10, 20, 40 and 200 mT for...Figure 1.25 The magnitude of the B0 fringe field (solid lines, logarithmic L...Figure 1.26 Simulated electric (L) and magnetic fields (R) from an eight‐run...Figure 1.27 RF pulse consisting of the carrier (Larmor) frequency multiplied...Figure 1.28 (a) the RMS value of a sinusoid is the peak amplitude divided by...Figure 1.29 MR device labeling according to ASTM‐F2503 (IEC‐62570) [6]. The ...2 Chapter 2Figure 2.1 Electric field lines begin at a source of positive charge and ter...Figure 2.2 Magnetic field lines from a permanent bar magnet.Figure 2.3 Electric fields induced by a time‐varying magnetic field form com...Figure 2.4 Electromagnetic wave: the magnetic and electric fields are orthog...Figure 2.5 Magnetic field lines from a long straight conductor carrying curr...Figure 2.6 Relative magnitude of Bz along the z‐axis for a long straight wir...Figure 2.7 Solenoid coil showing the angle θ. For a very long solenoid θ →90...Figure 2.8 B and dB/dt along the axis of a simulated shielded and unshielded...Figure 2.9 Magnetic susceptibility spectrum.Figure 2.10 Domains in a ferromagnetic material as the external field is inc...Figure 2.11 B‐H curve for 416 stainless steel (blue line) and its magnetic p...Figure 2.12 The hysteresis curve for a ferromagnetic material. The orange li...Figure 2.13 Demagnetization field within objects magnetized by an external m...Figure 2.14 Reciprocal demagnetization factors for a cylinder: 1/d1 (axial, ...Figure 2.15 Predicted internal B for a ferromagnetic sphere and cylinders of...Figure 2.16 B, dB/dz and product B.dB/dz along the z‐axis for: (a) a shielde...Figure 2.17 Predicted translational force (logarithmic scale) on spherical a...Figure 2.18 Influence of angulation of ferromagnetic objects with respect to...Figure 2.19 Predicted translational force on spherical and cylindrical 0.1 k...Figure 2.20 Predicted projectile velocity for the objects and magnets in Fig...Figure 2.21 Torque Τ on a ferromagnetic object of length l. The force on eit...Figure 2.22 Relative torque as a function of: (a) angle; (b) ratio of length...Figure 2.23 Predicted torque for ferromagnetic 0.1 kg objects of varying l/d...Figure 2.24 Predicted maximum twisting force (solid lines) and translational...Figure 2.25 The Lorentz force on a straight conductor with (a) B into the pa...Figure 2.26 Magneto‐hydrodynamic and Hall effect.Figure 2.27 Ohm’s law in a circuit and a volume conductor.Figure 2.28 B1 uniformity map for a head phantom at 7 T showing the effect o...Figure 2.29 Field regions in air and within the patient’s tissues. In the in...Figure 2.30 Measurements of B1 and E1 in a gel phantom on axis and off‐axis ...
3 Chapter 3Figure 3.1 Magnetic forces in biology: (a) Hall effect; (b) Lorentz force; (...Figure 3.2 Relative strength of forces on molecules and ions.Figure 3.3 (a) Magneto‐hydrodynamic (Hall effect) artefact on an MRI ECG tra...Figure 3.4 Number of published studies of bio‐effects of static magnetic fie...Figure 3.5 Reactive oxygen species (ROS) results from in‐vitro studies. Deri...Figure 3.6 Magnetic field dependence of the kinetics of flavin oxidation in ...Figure 3.7 Acute sensory effects reported in the Netherlands occupational ex...Figure 3.8 Nystagmus caused by 7 and 3 T static magnetic fields: blue dots =...Figure 3.9 Temporal response of nystagmus at 7 T: horizontal movement (blue ...Figure 3.10 Vertigo and nystagmus: (a) B field variation with time showing o...
4 Chapter 4Figure 4.1 Early phosphene research: (a) Charles Le Roy’s “cure for blindnes...Figure 4.2 Induced E‐field and current density J from a uniform time‐varying...Figure 4.3 Induced E‐field and current density J in an elliptical cross sect...Figure 4.4 B and dB/dt magnitude for Gz relative to a supine patient. dB/dt ...Figure 4.5 Variation of B and dB/dt from gradients Gx, Gy, and Gz. Field mag...Figure 4.6 (a) A uniform magnetic flux density Bz; the strength of the field...Figure 4.7 Modelling of induced electric fields: (a) from the y‐coil for dB/...Figure 4.8 Magneto‐phosphene threshold v frequency; data from various source...Figure 4.9 Strength duration curve showing the rheobase (the minimum thresho...Figure 4.10 (a) Structure
