Eugene W. Caldwell Lecture. Why Caldwell?

Every year for the past 75 years, the American Roentgen Ray Society has honored Eugene W. Caldwell by including the Caldwell Memorial Lecture as one of the features of the society's annual meeting. In this anniversary year--a year that highlights the history of radiology--it is appropriate to look back on Caldwell's career to examine the reasons for the society's decision to honor him, rather than numerous other eminent radiologists who might have been selected in his place. In the first Caldwell lecture in 1920, Walter Alvarez said, "Caldwell was a pioneer, an inventor, a research worker, a versatile, enthusiastic, and lovable man" [1]. Surely, many radiologists who lived during Caldwell's lifetime and who came later--including some living today--can be described in this way. The purpose of this essay is to offer an explanation of why Caldwell was chosen over the others.