This chapter comprehensively examines the pivotal advancements in X-ray technology during the early twentieth century. Covering a decade of rapid innovation, it highlights the contributions of pioneers such as Wilhelm Conrad Röntgen and other innovators who transformed X-rays from a scientific curiosity into a vital medical tool. The chapter details specific technological breakthroughs, including the introduction of the Coolidge tube, which revolutionized X-ray production and detection. It also discusses the development of early safety protocols, which emerged in response to the harmful effects of X-ray exposure recognized by these pioneers. Expanding on medical applications, particularly in oncology, the chapter illustrates how X-rays became essential in cancer diagnosis and treatment. These advancements not only laid the foundation for modern radiography and radiation therapy but also significantly altered public health practices and perceptions, leaving a lasting impact on medical diagnostics and treatment.