Abstract
When a small glass capillary tube, containing about one millicurie of radium emanation, is imbedded in living tissues definite localized destructive reactions occur, mainly due to the relatively intense betaray radiation given off in the immediate vicinity of the tube.
Bagg has shown that when normal brain tissue is thus treated, and examined after a period of about two weeks, the tissue about the tube is completely necrotic, and is surrounded by a broad zone of polynuclear leukocytes beyond which there is some hyperemia. The entire lesion is limited to an area 1 cm. in diameter. The lesion is well localized, the brain cells beyond the onecentimeter zone retain their normal morphological character. That the lesion is practically entirely due to the irradiation of the radium emanation, and not to the presence of the glass tube, or the traumatism incident to its insertion, has been satisfactorily proven by control experiments.
The lesion just described is not produced at the time the small tube is placed in the tissues. From previous data obtained by examining various radiated areas at different periods after the time of insertion, it was found that the lesion slowly increased in size. At the end of 24 hours the zone of necrosis about the tube was only 1 mm. wide, and the maximum area of destruction (1 cm. in diameter) was reached at about the end of two weeks. The radium emanation loses its activity at the rate of 16 per cent. per day, and in clinical usage the tubes, when used as in this method, are said to have an effective period of irradiation equal to 132 hours.
In our experiments similar slowgrowing, localized lesions were experimentally produced in the corpora striata of normal adult dogs.
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