3.1 X-Rays

• X-rays: Works due to due to a negatively charged electrode (cathode) hitting a metal plate (anode) at high velocity. This is due to an electron in an atom being hit and directed away from its path by an incoming x-ray photon.

• Advantages:

  • Quick

  • Available

  • Good bone detail

  • Good lung detail

• Disadvantages:

  • Ionizing radiation

  • Poor soft tissue detail

  • 2D representations of 3D structures.

3.2 CT Scan

• CT: Same mechanics as an x-ray but the tube the electrons are passing through is much smaller and the device is rotated many times around the patient to form a 3D representation of internal structures.

• Concepts:

  • Anatomical planes

  • Orientation

  • Density

  • Windowing

  • Contrast

• Advantages:

  • Still quick

  • 3D View

  • Can see vascular structures (with contrast)

• Disadvantages:

  • Very high ionizing radiation

  • Can't see spinal cord

  • Less detail in the brain

  • Poor tendon/ligament detail.

3.3 Nuclear Medicine

• Nuclear Medicine: Radioactive substances are injected into the body, and a special device measures the movement of the radioactive substances.

• Advantages:

  • Provides functional information, depending on the pharmacokinetics of the radioactive isotope.

• Disadvantages:

  • High ionizing radiation

  • Poor anatomical detail

3.4 Ultrasound

• Ultrasound: Functions due to the piezoelectric effect in which waves are sent and reflected back and a special device can display these signals. Anechoic (black appearance) is most likely fluid/liquid while Isoechoic (whiter appearance) is most likely solid (related to tumors).

• Advantages:

  • Quick

  • Available

  • No radiation

  • Repeatable

  • Excellent soft tissue detail

• Disadvantages:

  • Operator dependant

  • Can't see through bone

  • Can't see through the air

3.5 MRI

• MRI: When a person lies inside an MRI the magnetic field temporarily realigns water molecules in your body, radio waves cause these aligned atoms to produce faint signals, which are used to create cross-sectional MRI images.

• Advantages:

  • Excellent soft tissue detail

  • Fluid sensitive (can see oedema)

  • No ionizing radiation

• Disadvantages:

  • Very slow

  • Contraindications as it may cause harm

  • Claustrophobic

  • Bony detail is not as good as x-ray or CT