Tolerance of Central Nervous System 

 Structures in Man to Thermal Neutrons* 



L. E. Farr, W. G. Calvo, Y. L. Yamamoto, E. E. Stickley, 

 W. Haymaker. t and S. W. Lippincott 



Brookhaven National Laboratory, 

 Upton, Neiv York 



During the past several years at Brookhaven National Laboratory, the 

 experimental procedure of neutron capture therapy of intracranial neo- 

 plasms has been investioated utilizing a nuclear reactor as a neutron source 

 I Farr ct at., 1954-1960). In neutron capture therapy there are two main 

 components to the therapeutic system : the capture or target atom and the 

 thermal neutron or triggering component. As a result of thermal neutron 

 capture, an atomic transformation occius with release of energy. When the 

 target atom is boron- 10. the thermal neutron capture triggers an immediate 

 disintegration of the B'" into an energetic lithium-7 atom and an energetic 

 alpha particle with a modest gamma ray emission, totaling an energy release 

 of 2.8 Me\'. The restricted distribution of the energy release to a volimie of 

 one average cell proxides a selectixity of action that, in principle, will aflfect 

 one cell suitably primed and loaded, while the adjacent cell is totally un- 

 scathed. It is of importance in the development of a new therapeutic 

 modality to determine not only the efl'ect on the disease process, but also the 

 possible effects on residual normal cell structiues. Since large mnnbers of 

 thermal neutrons must penetrate tissue within a few minutes at most, the 

 tolerance of the central nervous system to thermal neutrons becomes a matter 

 of great practical, as well as theoretical, interest. Fortunately, the conditions 

 of therapy permit a study of neutron effects to be made relati\ely inde- 

 pendent of the B^" captiue reaction, since the distribution of the two com- 

 ponents of the reaction differ widely at the time of exposure. 



This presentation deals with observations made on patients so treated, 

 with one patient receiving only thermal neutrons. In addition to the clinical 

 obsenations, a combined topographic and histopathologic surxey was made 

 of the irradiated brains. 



* This research was supported by the U. S. .\toniic Energy Commission. 

 t Research collaborator from the Armed Forces Institute of Pathology, Washing- 

 ton. D. C. Present .Address: N.^S.^ .^mes Research Center. Moftett Fifld. California. 



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