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The German physicist Wilhelm Röntgen (Figure 1)1discovered the radiation known today as X-rays or Röntgen rays on 8th November 1895 while investigating the external effects of radiation from various types of vacuum tubes. Using a thin aluminum “window” that allowed light to exit the tube while maintaining the necessary vacuum, he observed fluorescence on a small screen outside the tube, even when the window was covered with cardboard. While he was investigating the ability of various materials to block the rays, Röntgen saw the world’s first radiographic image, his own flickering skeleton on a special screen. In December 1895, he published his paper2, “On a New Kind Of Rays”, with the first X-ray published (Figure 2)3.
In 1896, the French physicist Henri Becquerel discovered that uranium salts emitted rays that resembled X-rays in their ability to penetrate solid objects. He demonstrated that this radiation did not depend on an external source of energy but seemed to be emitted spontaneously by uranium itself. The Polish physicist Marie Curie discovered other radioactive elements (polonium and radium). She postulated the theory of radioactivity 4 that explains why some elements lose energy in the form of radiation, transforming themselves spontaneously and “decaying” throughout the years. She also conducted the first studies on the treatment of cancer using radioactive substances.