The paper is dedicated to the 110th anniversary of discovery of the X-rays, as well as to highlighting the importance and social value of physical discoveries in our everyday life. In the paper we deal with the description of physical principles of screening methods used in medicine. These include, alongside the X-rays, various tomographic methods and the most recent method of nuclear magnetic resonance. The content of this paper is in accordance with the fact that the year 2005 has been declared as the year of physics.