[en] This study was undertaken in an attempt to interpret the disappointing results obtained in the renewed clinical trials in boron neutron capture therapy (BNCT) at the Brookhaven Medical Research Reactor (BMRR) at the Brookhaven National Laboratory (BNL) during the mid to late 1990s. In BNCT, more than ∼75% of the radiation dose is due to the high-LET radiation by-products of the ¹⁰B(n,α)Li reaction, the α particles and Li ions. Therefore, the most crucial information that is needed to prescribe a therapeutic dose for the patient and affect successful therapy is the concentration of boron present in the tumor during the irradiation interval relative to that in the surrounding normal tissues. A tumor to blood boron uptake ratio was used for estimating the boron dose to tumor during the BNCT irradiation. It was based upon biodistribution data obtained from patients participating in a dose escalation study. Data from patients receiving different dosages of the drug p-boronophenylalanine (BPA-F) were combined on the assumption that BPA uptake in tumor was a linear function of dose. However, evidence providing a basis for the assumption was not reported. It was also assumed that BPA uptake was a linear function of the number of viable cells present in histological sections of tumor. Based upon these assumptions of linearity, arithmetic normalization was applied to the measured boron values yielding tumor boron uptake values that were higher than those actually measured and a higher tumor to blood ratio. The results of the analysis presented in this summary suggest that the patients who participated in the recent clinical trials at BNL may have received a radiation dose lower by ∼50% than that which was intended