The computed tomography scanner (invented in 1997) and magnetic resonance imaging (invented in 1977). Learn more about the many ways in which Johns Hopkins Medicine helped develop and improve the fields of health, medical education, and research. The invention of the microscope was the result of better understanding during the Renaissance. Before the 19th century, humorism (also known as humoralism) was thought to explain the cause of diseases, but it was gradually replaced by the germ theory of disease, leading to effective treatments and even cures for many infectious diseases.
Military doctors promoted methods of treating trauma and surgery. Public health measures were especially developed in the 19th century, as the rapid growth of cities required systematic health measures. Advanced research centers were opened in the early 20th century, often connected to major hospitals. The middle of the 20th century was characterized by new biological treatments, such as antibiotics.
These advances, along with advances in chemistry, genetics, and radiography, led to modern medicine. Medicine became largely professionalized in the 20th century, and new careers opened up for women as nurses (starting in the 1870s) and as doctors (especially after 1970).