OR to the therapy room and back to the OR. However, this solution has its own disadvantages: Remodeling an OR and purchasing an accelerator is expensive. Moreover, IORT is restricted to that one, specialized OR. Even so, the Mayo Clinic model demonstrated that when therapy equipment is located within an OR, the number of IOERT procedures will increase. In 1985, IOERT began in Italy and involved a specialized method to facilitate surgery followed by transport to the radiotherapy treatment room. Around the same time in France, another IOERT method was developed using the Lyon intra-operative device. In 1982 the Joint Center for Radiation Therapy (JCRT), at Harvard Medical School, attempted to reduce the cost of performing IORT in an OR by using orthovoltage X-rays to provide the intraoperative dose, which was similar to the approach used in Germany in 1915. But this was less than ideal. While the shielding costs and the cost and weight of the equipment compared favorably with conventional electron accelerators, dose distributions were inferior; treatment times were longer; and bones received a higher radiation dose. For these reasons, the centers rejected IO orthovoltage (X-rays) radiation therapy machines. In addition, these orthovoltage machines (300 kvp) were not designed to be mobile. Advent of Portable Linear Accelerators In the 1990s, electron IORT experienced resurgence, due to the development of mobile linear accelerators that used electron beams—the Mobetron, LIAC, and NOVAC-7 -- and the increasing use of IOERT to treat breast cancer. Prior to the invention of portable LINACs for IOERT, clinicians could only treat IORT patients in specially shielded operating rooms, which were expensive to build, or in a radiotherapy room, which required transporting the anesthetized patient from the OR to the LINAC for treatment. These factors were major obstructions to the widespread adoption of IORT because they added significant cost to treatment as well as logistical complications to surgery, including an increased risk of infection to the patient. Because portable LINACs for IOERT produced electron beams of energy less than or equal to 12 MeV and did not use bending magnets, the secondary radiation emitted was so low that it didn’t require permanent shielding in the operating room. This greatly reduced the cost of either constructing a new OR or retrofitting an old one. By using mobile units, the possibility of treating patients with IORT was no longer restricted to the availability of special shielded operating rooms,