Wilhelm Conrad Roentgen

Wilhelm Conrad Roentgen, discoverer of X-rays.

Diagnostic imaging is commonly dated from the discovery of X-rays on November 8, 1895. The discoverer was Wilhelm Conrad Roentgen (also spelled Röntgen), a professor of physics at Würzburg University in Würzburg, Germany. Roentgen was conducting experiments on what happened to various kinds of vacuum tubes when electrical current was passed through them. He had darkened the room and was in the middle of altering his setup when he noticed light shining in the lab even though he had covered the vacuum tube with heavy black paper. The light was coming from a barium platinocyanide screen he had set on a table a few feet away.

Puzzled, Roentgen repeated the experiment. He speculated that the cathode ray tube under scrutiny was emitting some kind of rays. In his notebook, he referred to these mysterious rays as “X-rays.” The name has stuck ever since.

Early Experiments with X-Rays

Roentgen’s early experiments revealed much of what we know about X-rays. He found that the rays emitted by the cathode ray tube passed through many substances and that they cast shadows of solid subjects they encountered. Roentgen found that the rays could pass through human tissue, but not bones or metal. Before the year was out, Roentgen had convinced his wife, Bertha, to come to his lab so he could photograph the bones in her hands. The day of medical imaging had dawned.

Roentgen hurriedly wrote up his findings in a paper, “Regarding a New Kind of Rays,” which was published on December 28, 1895, in the journal of the Physical and Medical Society of Würzburg.

Medical Uses for X-Rays

Cathode ray tubes were readily available to scientists of the day, and many repeated Roentgen’s experiments with the same results. Scientists began studying X-rays and their properties. Roentgen continued his studies as well, publishing his findings in additional papers. Roentgen realized very early that the non-intrusive view into the interior of the human body provided by X-rays could help physicians make better diagnoses and plan more effective treatment.

Physicians rushed to adopt the new technology. “Radiographs” that function according to the same principles as modern X-ray machines were set up in hospitals in Europe and the United States within a month of Roentgen’s discovery. Within six months, X-ray machines had been deployed to battlefield medics to help locate bullets in wounded soldiers.

X-ray machines were soon deployed to help physicians locate foreign bodies within their patients, evaluate bone breaks and fractures, and diagnose other diseases. Early X-ray machines were especially useful in assessing the health of patients suspected of having contracted tuberculosis.

A Researcher’s Acclaim

In recognition of the value of X-rays to the medical profession, Würzburg University awarded Roentgen an honorary Doctor of Medicine degree. He received numerous other awards for his work as well, including, in 1901, the first Nobel Prize ever awarded in physics.

The Nobel Prize includes a cash stipend, but Roentgen donated his to the university. He also declined to patent his discovery. For the rest of his life, he insisted at X-rays should be used only for the benefit of humanity.

Stay tuned for A Brief History of Radiology: Part 2