Radiographers (radiologic technologists) are healthcare professionals who perform medical imaging and radiation therapy. medical imaging is used for the diagnosis of pathology, while radiation therapy is used for treatment.

The duties and responsibilities of a radiographer include performing radiographic examinations, arranging radiographic examination projections with precision, carrying out radiotherapy procedures for disease treatment, being responsible for the radiation dose delivered to patients, conducting nuclear medicine examinations, managing and utilising radioactive substances including radiopharmaceuticals, implementing radiation protection measures to ensure the safety of patients and healthcare workers, as well as educating and explaining to patients about the procedures to be performed.

Radiographers are allied health professionals who work in both public healthcare and private healthcare, and can be physically located in a range of clinical settings that provide diagnostic imaging or radiation therapy services — most frequently in dedicated diagnostic imaging departments or radiation therapy departments within hospitals. The practice varies from country to country and can even vary between hospitals in the same country.

Radiographers are represented by a variety of organizations worldwide, including the International Society of Radiographers and Radiological Technologists which aim to give direction to the profession as a whole through collaboration with national representative bodies.

For the first three decades of medical imaging's existence (1897 to the 1930s), there was no standardized differentiation between the roles that we now differentiate as radiologic technologist (a technician in an allied health profession who obtains the images) versus radiologist (a physician who interprets them). By the 1930s and 1940s, as it became increasingly apparent that proper interpretation of the images required not only a physician but also one who was specifically trained and experienced in doing so, the differentiation between the roles was formalized. Simultaneously, it also became increasingly true that just as a radiologic technologist cannot do the radiologist's job, the radiologist also cannot do the radiologic technologist's job, as it requires knowledge, skills, experience, and certifications that are specific to it.

Radiography's origins and fluoroscopy's origins can both be traced to 8 November 1895, when German physics professor Wilhelm Röntgen discovered the X-ray and noted that, while it could pass through human tissue, it could not pass through bone or metal. Röntgen referred to the radiation as "X", to indicate that it was an unknown type of radiation. He received the first Nobel Prize in Physics for his discovery.

There are conflicting accounts of his discovery because Röntgen had his lab notes burned after his death, but this is a likely reconstruction by his biographers: Röntgen was investigating cathode rays using a fluorescent screen painted with barium platinocyanide and a Crookes tube which he had wrapped in black cardboard to shield its fluorescent glow. He noticed a faint green glow from the screen, about 1 metre away. Röntgen realized some invisible rays coming from the tube were passing through the cardboard to make the screen glow: they were passing through an opaque object to affect the film behind it.

Röntgen discovered X-rays' medical use when he made a picture of his wife's hand on a photographic plate formed due to X-rays. The photograph of his wife's hand was the first ever photograph of a human body part using X-rays. When she saw the picture, she said, "I have seen my death."