Radiology is the branch of medicine that deals with the diagnosis and treatment of disease using X-rays and other forms of ionising and non-ionising radiation. It includes diagnostic radiology, therapeutic radiology and nuclear medicine.

Radiology has two types of practitioners: radiologists and radiologic technologists. Radiologists are physicians who have completed a residency in one of the branches of radiology. Radiologic technologists are individuals who have completed training in an accredited program dealing with one of the branches of clinical radiology.

Radiography is the production of radiographic images for use in the diagnosis of disease using ionising radiation. A common example of radiography is a chest X-ray or radiograph. Computerised tomography or CAT scanning, referred to as CT, is another form of radiography performed by radiologic technologists.

Radiology is practised by licensed physicians. Diagnostic radiologists are responsible for interpreting the images created by technologists. They dictate their interpretations, which are transcribed into reports that become part of patients' permanent medical records.

Radiologists specialise in several subcategories of radiology. The most common category is diagnostic radiology. Interventional radiologists use X-rays and catheters to treat disease. Nuclear medicine uses radioactive isotopes in the diagnosis and treatment of disease. And therapeutic radiology uses ionising radiation to treat disease.

Technologists also specialise in subcategories of radiologic technology. The most common subcategory is radiography. Other categories include computed tomography, MRI, mammography, ultrasound, special procedures, nuclear medicine and therapeutic radiology.