ABSTRACT
Equipment selection based on machine energy has played a major role in past and present applications of intraoperative radiation therapy (IORT). Before high-energy electrons from betatrons or linear accelerators became available, ortho voltage X-ray units with increasing kilovoltage potential (50 to 250 kilovolt peaks [kVp]) were used. In this chapter, we discuss the development of early orthovoltage equipment and the role of modem equipment in contemporary radiotherapeutic practice.
