Imaging Methods

Imaging Methods

Introductory Concepts

  • Medical imaging techniques provide visual representations of the interior of the body for diagnostic and therapeutic purposes.
  • They involve the use of various types of energy waves, including electromagnetic waves and sound waves.
  • These imaging methods allow clinicians to observe signs of disease or injury without the need for invasive procedures.

Radiography

  • A basic form of medical imaging where X-rays are passed through the body to create images.
  • X-rays are absorbed more by denser tissues (like bones) creating a contrast between different types of tissue.
  • It is widely used in the diagnosis of fractures, lung diseases and the detection of foreign objects.

Magnetic Resonance Imaging (MRI)

  • MRI uses a magnetic field and radio waves to create detailed images of the organs and tissues within the body.
  • It does not involve X-rays and is particularly useful in imaging the brain and spinal cord.
  • The patient must be still during an MRI as movement can distort the images.

Computed Tomography (CT)

  • CT scans involve using X-rays to obtain cross-sectional images or ‘slices’ of the body.
  • A CT scan allows for a more detailed image than a standard X-ray, making it better for diagnosing diseases and monitoring treatments.
  • Because it uses X-rays, there is a risk of exposure to radiation.

Ultrasound

  • Ultrasound imaging uses high-frequency sound waves to produce images of the structures within the body.
  • It is commonly used in pregnancies to observe the development of the foetus.
  • Ultrasound is a safe and non-invasive procedure, but the images are typically not as detailed as those from a CT scan or MRI.

Positron Emission Tomography (PET)

  • PET scans use a small amount of radioactive material, called a radiotracer, which is detected by a PET scanner to produce 3D images.
  • This imaging method allows clinicians to observe how organs and tissues are functioning.
  • PET scans are useful in oncology for diagnosing cancers and monitoring response to therapy.

Safety Aspects

  • Whilst medical imaging provides invaluable diagnostic information, there are potential risks associated with radiation exposure from techniques like radiography and CT scans.
  • Alternative, non-radiation techniques like MRI and ultrasound should be considered where appropriate.
  • Proper safety protocols should be observed at all times, including shielding for patients and operators and the use of these techniques only when medically necessary.