ABSTRACT
The discovery of x-rays in 1895 by Wilhelm Conrad Röentgen began a new era of research and therapeutic/medical use of radiation. The “new kind of ray” or x-ray (x for unknown) was discovered during experiments on cathode rays. In 1896, the fi rst radiograph image was captured of a hand during a public lecture by Röentgen, and the Lancet published a report on how x-rays were used to fi nd a piece of a knife in the back of a paralyzed sailor (Hall 2000). Less than 20 years later in 1914 during World War I, Marie Curie set-up mobile radiology vans and x-rays were used for diagnostic imaging to help treat soldiers at the front. Great advances were made in the late 19th century with the discovery of radioactivity by Antoine Henri Becquerel and the isolation of radium by Pierre and Marie Curie. The use of radiation to kill or damage human tissue was demonstrated in 1897: Wilhelm Alexander Freud used x-rays to treat a hairy mole on an individual, and Henri Becquerel irradiated himself by leaving a vial of radium in his vest pocket, resulting in skin erythema and ulceration two weeks later. Over the last century, we have answered many questions about radiation, its effects on the cell and how it can be used therapeutically. This Chapter will address the present understanding about how ionizing radiation damages the DNA and how the DNA repair pathways (see Chapter 1) repair or misrepair the damage.
