Medical illustration is one well known human anatomy textbook that showcases a variety of anatomy depiction techniques. In 1895, Konrad Roentgen, a German physicist discovered the X-Ray. Internal imaging became a reality after the invention of the X-Ray. Since then internal imaging has progressed to include ultrasonic, CT, and MRI imaging. As a profession, medical illustration has a more recent history. In the late 1890s, Max Brödel, a talented artist from Leipzig, was brought to The Johns Hopkins School of Medicine in Baltimore to illustrate for Harvey Cushing, William Halsted, Howard Kelly, and other notable clinicians. In addition to being an extraordinary
Roentgen (unit) 1962 it was redefined. The CCU decided to define the SI unit of absorbed radiation in terms of energy per unit mass, which in MKS units was J/kg. This was confirmed in 1975 by the 15th CGPM, and the unit was named the "gray" in honour of Louis Harold Gray, who had died in 1965. The gray was equal to 100 rad. The definition of the roentgen had had the attraction of being relatively simple to define for photons in air, but the gray is independent of the primary ionizing radiation type, and can be used for both kerma and