R01.1: Early Observations

The Discovery of X-Rays and Radioactivity

Wilhelm Roentgen, a German engineer and physicist, was the first to discover and characterise x-rays. During experiments with a Crooks tube, he found that photographic plates distant to the tube began to develop despite the distance and absence of visible light reaching them.

(image located in the Congress Library, freely available)

Roentgen presented his results in late 1895; by January 1896 the news was widespread (as the tubes themselves were already being studied all over the world) and within months the potential use of these new 'x-rays' was being employed on patients with cancer. It was soon noticed that prolonged exposure to x-rays led to development of dermatitis and then several doctors proposed using x-rays in the treatment of cancer.

Early Optimism and Pessimism

George MacKee wrote in his book on X-Rays and Radium in the Treatment of Diseases of the Skin that the initial use of radiation for imaging and treatment was initially optimistic before the toxicities of exposure to x-rays became more apparent. This was due to several reasons, including a lack of understanding about what x-rays were, difficulty in their measurement, or in their interactions with matter.

Long term effects were often poorly understood. For example, here is an image of a doctor examining a patient using a fluorescent screen; the x-rays pass from the emitter to the left of the picture, through the patient and then presumably into the doctor's head.


A textbook published in 1902 (second edition) explored the various uses of Roentgen Rays in the diagnosis and treatment of disease. The number of children irradiated by early adopters of the technology is somewhat terrifying to the modern radiation oncologist. A list of conditions for which radiotherapy was used for included:

  • Lupus
  • Syphilis
  • Ezcema
  • Hypertrichosis (excessive hair)
  • Psoriasis
  • Acne
  • Tuberculosis
  • Trigeminal neuralgia (!)
  • Neoplasms, particularly those of the skin but also Hodgkin disease and laryngeal cancer
  • Rheumatism
  • Exophthalmic goitre

Interestingly important aspects of patient care were already being developed at this time, notably shielding the x-ray tube so that the x-rays were only delivered in the desired direction, and that the tube should not be placed too close to the patient's skin. It was also noted that if erythema developed the radiation should be ceased until the reaction had lessened to prevent serious consquences; however the cause of the radiation reaction was not clear and was hypothesised to be due to a multitude of cases including UV rays or electrical discharge on the skin. The author notes that "several thousand of examinations by Roentgen Rays have been made at the Boston City Hospital alone, and always without unpleasant results following, demonstrates the entire harmlessness of these examinations when carried out with proper care." The book is a fascinating read 110 years later and can be found here.

X-rays were thought to be active against a wide variety of life including bacteria; articles were published demonstrating high rates of cell kill of bacteria. Lack of effectiveness and injuries from radiation led to a period of pessimism from 1906 to 1910-12. Despite this quackery continued:


BergoniƩ and Tribondeau

Jean Alban BergoniƩ was a French medical doctor and physicist. He was born in 1857 and worked as a military doctor. His later life was complicated by radiation injuries which required the eventual amputation of his arm.


Louis Tribondeau is less well remembered and worked in infectious disease and dermatology. He worked with Bergonie between 1904 and 1906. He seems to have died in 1917 from infectious disease in Corfu. He also worked in the Ottoman Empire and served in the French military extensively.

In 1906 BergoniƩ and Tribondeau forumulated the "Law of Bergonie & Tribondeau" which theorised that the radiosensivity of tissue was dependent on maturation and metabolism:

X-rays are more effective on cells that have a greater reproductive activity; the effictiveness is greater on those cells that have a longer dividing future ahead - on those cells of which the morphology and the function are the least fixed, thus in direct proportion to their reproductive activity and inversely proportional to their degree of differentiation

This 'law' continues to be reasonably applicable to the radiosensitivity of tissues and cancer today. A reprint of the article is available at PubMed: here.

Development of the Coolidge Tube

The Coolidge tube, invented in 1914, made the production of x-ray machines more effective as it used a hot cathode that emitted electrons due to heat rather than through the Crookes tube. This shortened exposure times and increased the strength of the x-rays created, allowing for deeper treatments.