Explain the basic principles of MR image production Essay

Explain the basic principles of MR image production - Essay ExampleThe frequencies absorbed in mag realiseic resonance ar in the megahertz (million cycles per second) and gigahertz (billion cycles per second) ranges. The absorption frequencies for any particular substance atomic tour 18 directly proportional to the strength of the magnetic theater. This characteristic is unique to magnetic resonance.There are deuce distinct subcategories of magnetic resonance. One of these, for which the absorbing particles are electrons, is cognise by either of two similar names electron spin resonance (ESR) or electron paramagnetic resonance (EPR). The other category, in which the absorbing particles are atomic nuclei, is called nuclear magnetic resonance ( nuclear magnetic resonance).2The resonances are actually the absorptions of particular frequencies and are found in EPR and NMR arises from some of the most fundamental properties of matter. A general theory of EPR and NMR must be derived from quantum mechanics, but a classical analogy provides some insight. In the familiar model, either atom has a massive nucleus containing N positively shaked protons and a number of uncharged neutrons. Outside the nucleus are N negatively charged electrons in various orbits or distributions. The number N, called atomic number, identifies the atom in the periodic table. 3Every electron and proton possesses, in addition to charge and mass, an indestructible amount of angular momentum or spin, the property that keeps a gyroscope spinning later the driving force is removed. Because moving charge always has magnetic effects, the combination of charge and spin makes either electron and proton a spinning permanent magnet, the strength or magnetic moment being several(prenominal) hundred times greater for electrons. A spinning electron can be compared to the spinning rove of a toy gyroscope. When the gyroscopes spin axis of rotation is off vertical, and the bottom end of the axis res ts loosely on a support, the unexpected happens. Instead of falling farther from the vertical under the force of the wheels weight, the spin axis rotates steadily around the vertical at a fixed angle from it, a motion known as precession. In EPR the electron is spinning and a microscopic magnet. The externally applied magnetic field supplies the extra force, and the electrons spin axis precesses. Resonant absorption occurs when the source frequency is synchronous with the precession frequency. A similar explanation applies to NMR. 4Magnetic Resonance Image ProductionFigure 1 illustrates the a simplified block diagram of generic MR imaging mechanism demonstrating the elements essential for the recognition and creation of MR signals and the materialisation of MR images. These components are as follows1) The RF mechanism (a) for the production of the magnitude of the RF magnetic field with the help oneself of a curl for transmitting mode, amplifier and a transmitter, b) for the dete ction of the free induction decay (FID), which is the result of the net magnetization to an RF pulse this is done by the help of a signal demodulator, a coil for