G485 Medical essay main points

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  • Created by: Alice
  • Created on: 03-06-13 15:19

Medical questions

MRI

·       Protons have spin

·       Precess about the magnetic field produced by a strong electromagnet at a larmor frequency

·       Transmitting coil produces a radio frequency equal to the larmor frequency

·       Protons resonate and flip to a higher energy state

·       When they relax to a lower energy state they emit radio waves

·       Relaxation time depends on surrounding tissue

·       Radio waves picked up by receiving coils

·       Gradient coils alter magnetic flux density through the body

·       Larmor frequency and radio waves given of during relaxation times varies through the body so the position of tissues can be identified

·       Computer processes the signals and generates an image

 

PET

·       A positron emitting source is used

·       A positron annihilates with an electron in the patient

·       This produces two gamma photons

·      

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