Magnetism and types of magnet

Magnetism and types of magnet used in MRI.

1. MAGNETISM BY DR NISHANT RAJ

2. INTRODUCTION All substances posses some form of magnetism-----Magnetic Susceptibility. Magnetic Susceptibility– Ability of a substance to get affected by external magnetic field and is relate to electron configuration of the atom.

3. DEPENDING ON MAGNETIC SUSCPETIBILITY PARAMAGNETIC DIAMAGNETIC FERROMAGNETIC

4. PARAMAGNETISM

5. EXAMPLES: Gadolinium,Melanin and Oxygen

6. DIAMAGNETISM EXAMPLES: Bismuth,Mercury,Copper and Carbon

7. FERROMAGNETISM EXAMPLES: Iron, Cobalt Nickel

8. MAGNETIC FIELD STRENGTH Expressed by notation B Primary field: B0 Secondary Field: B1 UNITS: Gauss and Tesla One tesla (1 T) is defined as the field intensity generating one newton (N) of force per ampere (A) of current per meter of conductor: 1 Tesla = 1N / (1A . 1m).

9. TYPES OF MAGNET IN USE FOR CLINICAL MRI PERMANENT MAGNET ELECTROMAGNET SUPERCONDUCTING MAGNET

10. PERMANENT MAGNET Low cost Open MRI Low magnetic field Strength: 0.2-0.5 Tesla Low resolution

11. ELECTROMAGNET(RESISITVE MAGNET)

12. SUPERCONDUCTING MAGNET SUPERCONDUCTOR:

13. STRUCTURE OF SUPERCONDUCTING MAGNET COMPONENTS: 1: Superconducting Wires: of Nb/ Ti Alloy 2.Helium: To cool the coil to -269 degree Celcius 3: Liquid Nitrogen and Radiation Shield: Prevents heat exchange between helium and surrounding.

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