Medical imaging techniques that use ionising radiation

Medical imaging refers to the different techniques used to obtain images of the body. Medical imaging comprises 2 areas:

• radiology;
• nuclear medicine.

In each of these areas, the different examinations that are performed are categorised according to the technology used.

Medical imaging techniques in radiology

Radiography

Radiography uses X-rays to produce an internal image of the body.

Radioscopy

Fluoroscopy uses X-rays to produce a real-time dynamic image of inside the body on a screen. By way of comparison, radiography is the photograph and radioscopy is the video.

Scanners: CT scans

Scanners use X-rays to produce a large number of images, which are used to create a 3D image of inside the body. The dose of radiation is much higher than with radiography.

Ultrasound and MRI scans do not use ionising radiation.

Ultrasounds and MRIs are medical imaging technologies that do not rely on ionising radiation. They can offer an alternative to scanners for some indications.

Imaging technology in nuclear medicine

Scintigraphy

A radioactive product is injected into the body. The tissue in the body absorbs this product and emits radiation, which is detected by a special device. The result is an image of the distribution of the radioactive product inside the body, which can help to understand how it works.

Single Photon Emission Computed Tomography (SPECT)

The radiation emitted by the radioactive product that has been injected is then measured by detectors that revolve around the patient. Measurements taken from different angles are converted into a 3D image showing the distribution of the radioactive product in the body.

Positron Emission Tomography (PET scan)

The radioactive product is mainly absorbed by cells that are very 'active'. A PET scan can therefore be used to visualise the parts of the body with elevated levels of cellular activity (tumours, infections, etc.). A complementary CT examination is often carried out to locate these zones even more accurately. This is referred to as a PET-CT scan.