Intraoperative Radiotherapy

Abstract

Intraoperative radiotherapy (IORT) is the delivery of a single large radiation dose to the tumor bed during surgical resection. This radiation modality is applied in association with surgery and external beam radiotherapy (EBRT) or chemotherapy in the treatment of locally advanced cancer of the abdomen, pelvis, neck, cranium, thorax and extremities [1] with the final goal of enhancing locoregional tumor control [2]. The initial clinical use of IORT dates back to the early 1900s, when IORT was performed using soft X-rays and moving patients from the operating room to the radiotherapy bunker. The first IORT using electron beams (IOERT) was carried out in November 1976 at Howard University, in a bunker equipped with an operating room. In the 1980s, in order to combine technical advantages of brachytherapy with logistic advantages of IORT, high dose rate brachytherapy IORT (HDR-IORT) was implemented at Memorial Sloan-Kettering Cancer Center, using a portable HDR machine (OMIT) [2, 3]. Since the 1990s dedicated linear accelerators have been created to solve IORT logistical problems. Currently, 220 mobile units are installed worldwide: 40% in the United States, 35% in Europe and 25% in Japan. There are three principal models used in clinical practice [4]: Mobetron, from “Intraop Medical Incorporated”, California USA, Novac 7 (Fig. 5.1), from “New Radiant Technology”, Italy and Liac from “Sordina”, Italy. These machines are small linear accelerators producing electron beams which can be positioned directly in the existing operating rooms, with no special shielding required [5].