The history of medical X-rays has been treated before by numerous authors and from a multitude of perspectives (Clark 1955, Assmus 1995, Stamer 1995, Hofman 2010a,b, Mould 2011, Gunderman 2012, Nascimento 2014, Behling 2016 and many others). An excellent source of original communications with W.C. Roentgen can be found in Zehnder (1935). The present text may further increase appreciation for the individuals involved and the technical advances which have led to the present level of technology, and demonstrate the impressive scientific ambition in the period of the discovery of X-rays more than 120 years ago. Behling (2016) provides a historic treatment of the topic and includes an in-depth description of the technology, part of which is treated also in Chapter 2 of the present volume with respect to vacuum electronics and in Chapter 3 for the supply electronics. The text of this chapter cites parts of Behling (2016) but also goes further.