Continuing from our last post on the history of medical imaging…
Soon after x-rays were discovered, French scientist Henri Becquerel discovered naturally occurring radioactivity. He found, while investigating the properties of fluorescent minerals, that certain atoms self-disintegrated; he used photographic plates to record this fluorescence. When storing uranium with photographic plates in a closed drawer, he was shocked to later find they had been exposed by the uranium.
Becquerel’s discovery did not create much scientific interest, until the Curies discovered radium a couple of years later, in 1898. Radium was to become the initial gamma ray source (which would be commonly used in industrial radiography and for therapeutic purposes).
On May 9th, 1913, American physicist William Coolidge invented the hot cathode x-ray tube. It was known as the Coolidge Tube; it had an improved cathode which allowed for superior visualization of anatomy deep within the body, and also for better imaging of tumors. This was a major development in radiology; the basic design of Coolidge’s invention remains in use to this day.
Image sourced from www.crtsite.com
X-rays were used from the earliest times, not just for diagnostic purposes, but also for therapeutic concerns. Skin lesions were treated with some success, and deeper tissue conditions were soon treated with stronger x-ray apparatus and radium. While ionizing radiation is today of extreme value and importance in treating cancer and certain other conditions, one hundred years ago there was no understanding of the dangers posed by radiation – that discovery was yet to be made. Marie Curie actually worked to have radiography used to treat soldiers who were wounded during World War I.
Curie Radium Therapy – Picture courtesy of www.aip.org
It was inevitable that indiscriminate exposure to ionizing radiation would be harmful in these early days. Some health implications were noted early; however there was no reason for experimenters to see the link between side effects and x-rays at that time. Symptoms like skin burns had a slow and gradual onset. The first real warning came from Thomas Edison, Nikola Tesla, and William Morton, who each experienced and reported eye irritation after experimenting with x-rays and fluorescent minerals. (We will later look in depth at the developments in radiation protection to the standards we have today).
In the early 1900s, many members of staff took x-ray images and used x-rays for therapy in hospitals – everyone from doctors, to physicists, nurses, engineers, and photographers. Prior to 1918, the word used for one who took x-rays was “skiagrapher” (from the ancient Greek words for “shadow” and “writer”).
(Thereafter, the term “radiographer” has been used; in the USA, these professionals are called “x-ray technicians”. The medical doctor who is specialized in the field is called a “Radiologist”).
Until the 1930s, doctors in hospitals used x-rays for both imaging and therapeutic purposes. From the mid-1930s, however, those who worked with radiation were appointed to a specific interest in either diagnosis or therapy.
Next time – Part Three – Medical imaging developments from 1950.