THE POSSIBLE USE OF NEUTRON-CAPTURING ISOTOPES SUCH AS BORON10 IN THE TREATMENT OF NEOPLASMS. II. COMPUTATION OF THE RADIATION ENERGIES AND ESTIMATES OF EFFECTS IN NORMAL AND NEOPLASTIC BRAIN 1

Abstract

Data are presented to show the degree to which intraven. injected borax concentrates in malignant brain tumors and in normal tissues including brain. The amt. of biologic radiation damage arising from each element consequent upon exposure to a beam of slow neutrons has been roughly computed. The energy of ionization for each element is proportional to F, the flux of thermal neutrons, N, the number of atoms of the element, [sigma]a, the capture cross section of the element, E, the energy emitted after neutron capture, and A, the fraction of this energy absorbed in the tissue. On the basis of 50 [mu]g./g. of B10 in tumor and 15 [mu]g./g. in normal gray matter the computations show that the locus of the B atom would be the principal determinant of the site of damage. At the readily achieved differential concns. between glioma and brain of 3.3:1, the radiation damage in tumor would be about 3 x that in normal brain, if one assumes uniform distr. of the neutron flux.