Roentgenology

• Wilhelm Conrad Roentgen discovered X-rays on November 8th, 1895, while working in his laboratory in Wurzburg, Germany

  
• Roentgen discovered that X-rays were invisible but caused fluorescence in certain substances, darkened photographic plates, were propagated in straight lines, and behaved fundamentally different from cathode rays
• Roentgen's apparatus for X-rays originally used a variation of the Hittorf-Crooke’s tube developed by Philipp Lenard, with a small window of thin aluminum foil over an opening in the tube
• Cathode rays are streams of electrons observed in vacuum tubes, with at least two electrodes, a cathode (negative electrode) and an anode (positive electrode) in a configuration known as a diode
• In high vacuum, used in many Crookes tubes, X-Rays are produced, and the glass emits a green glow
• A.W. Goodspeed and William Jennings produced a radiogram in Philadelphia on February 22nd, 1890, placing coins on top of a glass photographic plate exposed to radiation via a Hittorf – Crooke’s tube
• Lenard experimented with Hittorf – Crooke’s tubes and produced X-rays but did not immediately grasp the importance of the finding, later resenting Roentgen throughout his life
• Heinrich Rudolf Hertz became the first person to broadcast and receive radio waves, and to establish that light was a form of electromagnetic radiation, experimenting with cathode rays
• Timeline Leading to Roentgen’s Discovery:

  • 1600: Gilbert's De Magnete laid the foundation for magnetism and electricity
  • 1675: Newton built a more efficient electrostatic generator
  • 1729: Gray distinguished conductors of electricity from nonconductors
  • 1750: Franklin defined positive and negative electricity
  • 1785: Morgan possibly produced x-rays in vacuum experiments
  • 1800: Volta constructed the first electrical battery, the Voltaic pile
  • 1820: Oersted discovered the link between electricity and magnetism
  • 1827: Ohm formulated Ohm's law
  • 1821: Faraday and Henry discovered electromagnetic induction
  • 1850: Plucker observed green-glass fluorescence in a vacuum tube
  • 1860: Toepler, Holtz, and Wimshurst improved electrostatic machines
  • 1873: Maxwell published his famous equations in "Treatise on Electricity and Magnetism"
  • 1879: Crookes found that cathode rays can be deflected by a magnet
• William Morton:

  • New York dentist
  • Credited with the first dental radiograph in the United States
  • Wrote a book on X-rays in 1896
• William H. Rollins:

  • Boston Dentist
  • Published over 200 articles on radiation effects and safety between 1896 and 1904
  • Called for radiation protection for radiation workers and patients in 1904
• Dr. Frank Van Woert:

  • Pioneer of oral and maxillofacial radiology
  • Demonstrated dental radiography before the New York Odontological Society in 1897
  • Used Kodak film instead of glass plates
• Howard Riley Raper:

  • Invented the bitewing radiograph in 1924
  • Introduced oral and maxillofacial radiology into the dental curriculum in 1910
  • Wrote the first textbook on the subject in 1913
• The dangers of X-rays:

  • Clarence Dally's death highlighted the dangers of X-ray burns
  • Dr. Edmund Kells developed cancer in his right hand due to cumulative doses of radiation from X-rays
  • Kells endured 42 operations and ultimately committed suicide in 1928
• Wilhelm Röntgen:

  • German physicist who discovered X-rays
  • Died in 1923 of carcinoma of the bowel, not believed to be a result of his work with ionizing radiation due to his use of protective lead shields
• Cathode Ray Tubes:

  Cross Vacuum Scale demonstrates the phenomenon of discharge at different pressures inside the tubes.

  The pressure varies between 40 Torr, lowest vacuum to 0.03 Torr, the highest vacuum.

  In this high vacuum, used in many Crookes tubes, X-ray are produced.

  The glass emits here a green glow.