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) Valentine Mayneord and the radiobiologist John Read, published a paper in which a unit of measure, dubbed the ""gram roentgen"" (symbol: gr) defined as "that amount of neutron radiation which produces an increment in energy in unit volume of tissue equal to the increment of energy produced in unit volume of water by one roentgen of radiation" was proposed. This unit was found to be equivalent to 88 ergs in air. In 1953 the ICRU recommended the rad, equal to 100 erg/g, as the new unit of measure of absorbed radiation. The rad was expressed in coherent cgs units. In