On Dec. 19, 2013, the Siteman Cancer Center debuted the first single-vault proton therapy center in the U.S.: The S. Lee Kling Center for Proton Therapy, for high precision proton beam radiation treatment.

Steven Osborne, a 33-year-old man from Leasburg, Mo., was the first patient to receive the revolutionary radiation treatment from the world’s first proton system. Osborne had a rare type of cancer called chondrosarcoma at the base of his skull and undwent 30- to 45-minute session each weekday for the seven weeks.