Absence of tissue reaction after focal high-dose irradiation of rabbit liver.

Background: A focal reaction of the liver is radiologically seen after stereotactic high dose radiotherapy of liver tumors. The histological counterpart of this reaction should be clarified using an animal model.

Materials And Methods: Six New Zealand white rabbits were positioned on a special stereotactic set-up. Parts of the liver (1.5-8 ml) were irradiated with either 20-24 Gy/80% (n = 3) or 36 Gy/80% (n = 3). The animals were followed by CT examination up to 2 years after radiotherapy. Finally, the animals were sacrificed and the liver macroscopically and microscopically inspected.

Results: No focal reaction could be observed in any liver at any time by CT examination. The liver macroscopically and microscopically showed no changes 6 months or 2 years after radiotherapy.

Conclusion: Up to a single dose of 36 Gy/80%, rabbits seem to show no focal tissue reaction after high dose radiation therapy of small parts of the liver.