 X-Rays  Nuclear Medicine  Medical Ultrasound  Magnetic Resonance Imaging

 Discovered in 1895 by Roentgen  An ionising radiation at a higher level on EM spectrum  Higher frequency or shorter wavelength

 Non-Invasive  Well established technology  Still evolving  Flexible  Readily available and therefore relatively cheap  Ionising Radiation  Not good at imaging soft tissue on its own

 Use of unsealed radioisotopes  Attached to pharmaceuticals  Drugs absorbed preferentially by target organ(s)  Gamma emitter so can be detected  Images digitally produced from data gathered

 Can image wide variety of tissue types  Easy to target specific tissue  Can image function  Utilises by-products of other processes so cost effective  Uses ionising radiation  Could be described as invasive  Has many radiation protection issues associated with it  Better applications are expensive

 Manipulation of natural magnetic field  Magnetic resonance is detectable and measurable  Data detected can be digitally converted to an image  Utilises tomographic techniques of CT

 Atoms have magnetic moments  They spin in a magnetic field – Precession  Spin frequency depends on the type of atom or molecule – Larmor Frequency  Examine the spin of hydrogen atoms  Hydrogen atoms in different tissues have different Larmor Frequencies

 Does not use ionising radiation  Excellent at demonstrating soft tissue  Non Invasive  Good at cancer diagnosis

 Non-Invasive  Does not use ionising radiation  Excellent for soft tissue imaging  Can image function  Very Expensive  Has its own health and safety issues  Has “acceptability” issues with some patients

 Utilises sound waves at ultrasonic frequency  Above 20KHz is ultrasound but usually MHz for medical imaging purposes  Echoes from tissue can be detected and data interpreted digitally to produce image  Position and depth of the echoes builds up a complete picture

 Non-Invasive  No ionising radiation  Dynamic technique  Can image soft tissue effectively  Flexible equipment  Relatively cheap  Limited in what can be imaged  VERY user dependant

 What information do we require?  Do we wish to see function or structure?  What can the patient tolerate?  What would the clinician prefer?  What is available for use?  Is there a safer/cheaper alternative?  Can potential risks be justified?