O. Arthur Stiennon, Jr. was a clinical radiologist, inventor, radiation treatment pioneer, software and real estate developer in Madison, Wisconsin. He attended the University of Wisconsin–Madison, graduating Phi Beta Kappa in 1941. He received his M.D. at the University of Wisconsin in 1943 under the wartime accelerated program. He served an internship at the Royal Victoria Hospital in Montreal, P.Q., Canada. After serving in the United States Army from 1944 to 1947, he served a residency in Diagnostic and Therapeutic Radiology at the University of Michigan Hospitals in Ann Arbor, Michigan.

A betatron is a type of cyclic particle accelerator for electrons. It consists of a torus-shaped vacuum chamber with an electron source. Circling the torus is an iron transformer core with a wire winding around it. The device functions similarly to a transformer, with the electrons in the torus-shaped vacuum chamber as its secondary coil. An alternating current in the primary coils accelerates electrons in the vacuum around a circular path. The betatron was the first machine capable of producing electron beams at energies higher than could be achieved with a simple electron gun, and the first circular accelerator in which particles orbited at a constant radius.