BNCT Microdosimetry and Brain-Tumor Patient Response
The most important parameter required to prospectively evaluate the likely success of BNCT is the binomial distribution, of the number of capture events per tumor cell, leading to tumor control. The number of tumor cells that statistically escape a cytocidal capture event is expected to be a particularly important parameter effecting paitent outcome. To provide insight into treatment parameters that must be exceeded for effective therapy, the experimentally verified, INEL-developed analytical dosimetry software, reported in the literature, has been utilized to compute the dose and stochastic parameters at the location of histologically or PET comfirmed recurrence in two U.S. patients treated in the Kyoto University thermal neutron beam. The capture-event statistics resulting in 1) little clinical benefit and 2) “near-control” are reported. The achieveable capture statistics are also reported assuming that these patients could have been treated using an ideal source of epithermal neutrons instead of thermal neutrons. The analyses suggest that tumor cell survival fractions in the range of 10−2 provide little patient benefit and survival fractions less than 10−3 will be required for therapeutic advantages relative to conventional treatment modalities. Analyses indicate that epithermal neutrons would have been able to provide beneficial treatment for both patients studied.
KeywordsNeutron Beam Boron Neutron Capture Therapy Epithermal Neutron Capture Event Neutron Fluence
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