354 ANDERSSON, LARSSON, LEKSELL. MAIR. REXED AND SOURANDER 



> u - t^J^v * ** :> X ?* '. 



Fig. 7. Twenty-three weeks after irradiation. Newly formed wide vessels lined with 

 flattened endothelium and surrounded by macrophages, some of then containing hemo- 

 siderin, now appear in the lesion. H. van G. X 200. The photographs are published 

 by courtesy of Acta Radiologica. 



ways were unafTected. though the proton beam often passed through parts 

 of these structures. 



Restricted Lesion in the Depth of the Brain 



To be able to compare the radiogenic brain lesions in rabbit and goat with 

 each other, 1 goat was irradiated with a single beam directed through the 

 frontal lobe of the right cerebral hemisphere (dose =^ 20 krad). The brain 

 was examined 1 month after irradiation. The lesion in this goat bore a 

 strong resemblance to the lesions in the brains of rabbits irradiated under 

 similar conditions. 



Lesions were produced in the internal capsule of 3 goats by the stereotaxic 

 method using cross fire irradiation. A dose of 20 krad was given to 2 of these 

 goats, 'iliey remained in good condition and did not show any symptoms of 

 cerebral injury. Four and 7 weeks after irradiation, they presented restricted 

 lesions in the selected areas (Fig. 8). The damaged region was roughly lenti- 

 forni, with a maximum thickness in the anterioposterior direction of about 

 3 mm. The longest diameter of the lesion was in the dorsoventral direction 



