Liver tissue tolerance for irradiation: Experimental and clinical investigations

Radiation treatment of the liver for malignant disease has gained renewed i nterest due to newly developed treatment modalities. Still limited specific knowledge is available concerning liver damage following irradiation. Inco nsistencies between reported animal experimental studies are largely due to differences in irradiation techniques and to varying Observation periods. Following the introduction of Megavoltage irradiation and the development o f more sophisticated irradiation techniques, clinical reports concerning mo re reliable studies became available. The reaction of the fiver to irradiat ion depends specifically on parameters as type of irradiation, dose, dose r ate, fractionation schedule, and irradiated volume. Also the use of cytotox ic agents and liver surgery are of importance for the ultimate therapeutic result. Radiation hepatitis in humans may develop following high-dose liver irradia tion resulting in clinical and histopathological disorders resembling a ven o-occlusive disease-like syndrome. These disorders may either totally or pa rtially recover or be progressive in time resulting in hepatic failure. It is concluded that depending on the variables mentioned, ionizing radiati on up to 35 Gy to the human liver, given to a limited volume, can be applie d without major liver function disturbances.