Final answer:
X-rays were discovered by accident when Wilhelm Röntgen found that they could pass through soft tissue but not denser bone, leading to breakthroughs in medical imaging. During World War I, Marie Curie advocated the use of mobile X-ray units for diagnosing soldiers. Radiology, the use of X-rays in medicine, remains a widely used diagnostic tool.
Explanation:
X-rays were discovered by accident by the German physicist Wilhelm Röntgen in 1895. The discovery occurred while Röntgen was experimenting with electrical currents and noticed that a certain invisible ray could pass through human tissue but would leave the shadow of bones on a screen coated with a metal compound. The ability of X-rays to pass through soft body tissue and be absorbed by denser materials like bone enabled, for the first time, doctors to see inside a living patient without surgery.
During World War I, X-ray technology became particularly useful in the medical field. Mobile X-ray units, which were advocated by Madame Marie Curie, greatly aided military doctors. These units were deployed to diagnose injured soldiers, improving medical care and enabling more effective treatments, such as the optimized removal of embedded bullets.
Furthermore, the use of X-rays in medicine, which is known as radiology, has become a central tool in diagnostics. Due to its relative cost-effectiveness compared to more sophisticated technologies, X-ray usage is widespread and extensive in medical diagnostics to this day.