The subject matter of the article is the iconology of X-ray images. This is introduced in the light of the science of pictures proposed by research conducted by Horst Bredekamp who carried out the project Das Technische Bild in the years 2000-2012. Following the German scholars’ proposition, I involve the analitical instruments of art historians to present scientific pictures as a visual construction formed by (scientific) imagination, laws and assumptions. We can speak about the undermining of the illustrative function of the scientific picture also when we scrutinize technical images such as a radiogram. In the iconology of X-ray pictures introduced, I indicate some chosen elements which co-constitute their cultural credibility and further scientific status. From such a point of view, an X-ray discloses itself not as an effect of discovery but as an invention determined by cultural, social and epistemological context.