TISSUE TOLERANCE OF NORMAL AND SURGICALLY MANIPULATED CANINE LIVER TOINTRAOPERATIVE RADIATION-THERAPY (IORT)

Purpose: The purpose of the study is to obtain dose guidelines for the delivery of intraoperative radiotherapy to the liver of patients with colorectal liver metastases. Following partial resection of the liver , a single high dose of 10, 20, 25, and 30 Gy intraoperative radiother apy was applied to both the resection plane as well as a nonsurgically manipulated part of the liver of 25 beagles. The temporal sequence of histological and ultrastructural changes of these irradiated parts of the liver tissue was investigated. Methods and Materials: The feasibi lity of delivering single large dose of intraoperative electron beam r adiotherapy to the normal and partially hepatectomized liver was exper imentally investigated in a canine study. Results: There were no posto perative complications, no morbidity or mortality with a minimal follo w-up of 1 year. Autopsy performed 3 months following irradiation showe d only mild histopathological changes. One year following intraoperati ve radiotherapy more distinct histopathological changes consisting of capsular thickening, diffuse parenchymal fibrosis and subcapsular hepa tocellular atrophy were found. The liver function remained intact. Con clusion: This study demonstrated that intraoperative radiotherapy to p art of the liver in the canine model can be safely applied and doses u p to 30 Gy are well tolerated.