X-Rays at 125 Years

David J. Allard

College of Physicians of Philadelphia

Wednesday, November 11, 2020 5:30 pm EST

Online Event

Register for this event here.
X-Rays at 125 Years: The Story of a Serendipitous Discovery Through Diligent Development
As with most major discoveries, there are incremental observations and often theoretical analyses that lead to a final momentous breakthrough. This was not the case with the discovery of X-rays 125 years ago this year. In fact, a serendipitous discovery by Wilhelm Conrad Röntgen of immense consequence occurred during a repeat of another’s experiment.
On November 8, 1895, Röntgen was examining the range of cathode rays (electrons) in the air from a modified Crookes tube. He named these invisible rays ‘X-rays’ as they were hitherto unknown, and published a paper in late December 1895 entitled “A New Kind of Rays.” In this paper he presented the vast majority of the properties of X-rays. Some of these properties included:

  • their ability to penetrate paper, a 1,000 page book, glass, flesh, and various metals of differing thickness
  • the inability to refract in water, a prism, or mica
  • their ability to darken photographic plates

During the course of his investigations, he produced images of the barrel of a shotgun, other inanimate objects, and his wife’s hand on photographic plates. It was this aspect of X-rays that quickly led to their use in medicine, in particular imaging broken bones and finding foreign bodies (e.g., bullets).
The cold cathode tubes employed were very inefficient in X-ray production, unstable, unable to penetrate thick body areas, and took a significant period of time to produce an image on a plate. Those limitations were overcome by William David Coolidge (1873-1975), who was a physicist, chemist, research scientist, and invented the modern X-ray tube. Besides Röntgen, with his 1895 discovery and subsequent studies of X-rays, perhaps no other individual contributed more to the advancement of X-ray technology than did Coolidge.
From notes of interviews with Coolidge’s son Lawrence in the mid-1990s, previous biographies, publications, books, GE literature, historic photographs (e.g., a wonderful 1874 stereoview card with the one year old baby “Willie Coolidge”), and other artifacts in the authors’ collection, this presentation will review Dr. Coolidge’s amazing life, work, accomplishments, and awards. There will also be a brief review of the many applications of X-rays in medicine, research, and industry.
*Virtual event details and instructions will be emailed to registered attendees.
Featured Speaker: David J. Allard, MS, CHP, FHPS
In March of 2019, Mr. Allard became the Pennsylvania DEP’s Acting Deputy Secretary for the Office of Waste, Air, Radiation & Remediation. He has recently returned to his position as Director of Bureau of Radiation Protection (BRP), and is responsible for the: accelerator, X-ray, environmental surveillance, nuclear safety, radiological emergency response, radioactive materials, decommissioning / site clean-up, low-level radioactive waste and radon programs within the Commonwealth. He is also the technical lead on Oil & Gas industry radium and NORM / TENORM issues for DEP. BRP has over 100 technical and administrative staff and a $15M annual budget. Mr. Allard is the Governor’s official liaison to the U.S. Nuclear Regulatory Commission, and one of the DEP’s Commissioners for the Appalachian States Low-level Radioactive Waste Compact Commission. Mr. Allard received an Associate in Applied Science degree in Environmental Health Technology from Hudson Valley Community College, a Bachelor of Science degree (cum laude) in Environmental Sciences from SUNY Albany, and a Master of Science degree in Radiological Sciences & Protection from U Mass-Lowell’s Department of Applied Physics. He is certified by the American Board of Health Physics, a Fellow of the Health Physics Society (HPS), and has acted as the Conference of Radiation Control Program Directors’ (CRCPD) liaison to the National Council on Radiation Protection and Measurement (NCRP) for over 15 years. He is also a member of the AAPM, ANS, NRRPT and SNMMI. Prior to joining DEP in February 1999, he was a consultant to the U.S. Department of Energy regarding environmental and occupational radiation protection issues for eight years. Mr. Allard has been involved in the various aspects of governmental, industrial, reactor, medical, and academic radiation protection for over 40 years. Early in his career he taught X-ray Physics and Radiation Biology in the Albany Medical Center school of Radiologic Technology. He has been in various leadership roles with the HPS and CRCPD; and is the immediate Past Chairperson of the CRCPD. Mr. Allard also serves as a member or advisor on several national and international radiation protection committees; he has authored numerous professional papers and reports; and, frequently lectures on a wide variety of radiation protection topics and concerns – including the history of radioactivity, radium and X-rays.
Please note:
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*The College of Physicians of Philadelphia reserves the right to record the virtual experience for marketing or promotional use.