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The liver is a large abdominal organ in the right hypondrium. Because of its anatomical situation, it is near many abdominal PTVs as well as some lower thoracic PVTs. The liver could also be at the same time the target (for irradiation of liver metastases or primary liver tumours) and organ at risk (OAR). Radiation-induced liver disease (RILD) is radiobiologically the normal tissue complication probability (NTCP), i.e., the clinical event limiting the total dose that could be delivered. This review describes radiobiological criteria justifying the NTCP data, and recommendations for conformal 3D radiotherapy and stereotactic liver irradiation., (Copyright (c) 2010 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)

Background: Intratumoral ablative therapy is being used increasingly for the treatment of primary and secondary hepatic malignancies. The interstitial point-source photon radiosurgery system (PRS) is a novel ablative technique that uses radiation therapy similar in dosimetry to interstitial brachytherapy., Study Design: To determine the feasibility, toxicity, and local tissue destructive capabilities of the PRS in the liver, preliminary studies in a nontumor-bearing canine model were examined. A 6-month survival study was conducted. Each animal received three radiation treatments, in the right, central, and left hepatic regions. Three low-dose treatments were delivered to each of six animals (group A), generating a 2.0-cm-diameter radiated sphere with a dose of 20 Gy at the lesion edge. Three high-dose treatments were delivered to each of six animals (group B), generating a 3.0-cm-diameter radiated sphere with 20 Gy at the lesion edge., Results: The treatment reproducibly generated sharply demarcated hepatic ablative lesions proportional to the administered dose. Mean lesion diameter at 1 month was 1.6+/-0.2 cm in group A and 3.4+/-1.0 cm in group B. Lesion size was independent of intrahepatic location, including near vascular structures. PRS therapy, when applied to portal structures, resulted in hilar damage. Hilar damage appeared to be associated with arteriolar thrombosis and bile duct injury. Treatment of regions adjacent to large hepatic veins and the IVC was not associated with vessel thrombosis or stricture., Conclusions: PRS ablation is a generally well-tolerated method that results in consistent, well-demarcated, symmetric lesions of complete necrosis with minimal adjacent parenchymal injury. Application of such an approach for the treatment of liver tumors is promising.