Stereotactic gamma radiosurgery of craniopharyngiomas

Ten cases of solid craniopharyngioma have been treated safely and effectively by gamma knife for a mean follow-up time of 13.9 months. Gamma radiosurgery was done as an initial radiotherapy to the residual or recurrent tumor after surgery in 8 cases. One recurrent tumor from surgery and conventional radiotherapy, and another tumor without previous treatment, have also been treated. Dose planning and dosimetry were performed using both axial and coronal MRIs. The tumor had a mean diameter of 21.1 mm and volume of 6.14 cm3. The tumor was treated with a mean maximum and marginal dose of 27.6 and 14.2 Gy respectively. The dose to the optic pathways is critical and was kept as low as possible which was calculated to be < 13.0 Gy on average. As a result, marked shrinkage of the tumor in 7 and central necrosis in 3 tumors have been obtained without significant side effects.