Eugene W. Caldwell (1870–1918) was an American engineer, radiographer, and physician who conducted early work on the medical uses of X-rays.

In 1917, Caldwell was named chief of the new roentgen ray department at Columbia University, making him one of the first radiology professors in the United States.

After developing radiation burns and radiation-related cancer, he underwent numerous surgeries, including an arm amputation, shortly before his death.

He made friends with a number of students who became influential in their fields, including Herbert S. Hadley, who became the governor of Minnesota; Frederick Funston, who became an army general; and William Allen White, who became a newspaper editor and a leader in the Progressive movement.

Caldwell even applied his electrical knowledge outside the classroom; once he connected a wire to his doorknob that would deliver a shock to uninvited guests, and sometimes he ran cables to his friends' boarding houses so they could communicate by telegraph.

[3] Caldwell was inspired by Kansas physics professor Lucien Blake, who invited him on a trip to the eastern seaboard, where they worked together to develop submarine signaling technology.

One such connection was the editor of the New York Electrical Review, and their association led to Caldwell's publishing a series of articles on telephony.

When his friend Fred Funston went down to Mexico to grow coffee in the spring of 1896, Caldwell seemed tempted to go with him to get away from the climate of the American Northeast, but he decided to stay in the United States to continue his work with telephony.

The equipment turned out to be in poor condition, but by the end of the year Caldwell had repaired it and set up a small office on 53rd Street in Manhattan to take X-rays.

His work gained attention at the 1899 New York Electrical Exposition, where he displayed an improved induction coil that allowed X-ray images to be obtained in a fraction of the usual exposure time.

Around this time he began taking anatomy classes in the evenings as a special student at the College of Physicians and Surgeons so that he could better understand the medical implications of his X-ray work.

[10][9] In a fall 1901 article in the Electrical Review, Caldwell described a device he developed in his laboratory to add stereoscopy to X-rays.

[11] Caldwell enrolled at Bellevue as a medical student in 1902;[8] that year he was elected an associate of the American Institute of Electrical Engineers (AIEE).

With William A. Pusey, he published a textbook that year called The Practical Application of the Roentgen Ray in Therapeutics and Diagnosis.

[8] Later, in a speech to the New York State Medical Society, Caldwell described the difficulties created by the straightforward appearance of the X-ray image.

[9] In 1910, when New York City mayor William Jay Gaynor was shot, Caldwell was summoned to perform and interpret his X-rays.

[8] The next year, Harry Miles Imboden, an established physician with a newfound interest in X-rays, moved to New York City to become Caldwell's protégé.

[16] Caldwell became one of the first radiology professors in the United States when he joined Columbia University as chief of the newly established roentgen ray department in 1917.

At a memorial service at the Campbell Funeral Church, speakers included U.S. Army physicist and X-ray expert J. S. Shearer, who said it was strange that someone "of high genius and kindly in all his traits ... should pass away while active in the greatest conflict civilization has known.