Am. Kalend et al., DOSIMETRIC CONSEQUENCES OF B-10(N,ALPHA)LI-7 REACTION OCCURRING AT THE CELLULAR MEMBRANE, International journal of radiation oncology, biology, physics, 31(1), 1995, pp. 171-178
Citations number
19
Categorie Soggetti
Oncology,"Radiology,Nuclear Medicine & Medical Imaging
Purpose: Microdosimetric expectations of Boron contents are extracted
from a CRAY-Monte Carlo simulation of the nuclear reaction B-10(n,alph
a)Li-7 as it occurs on a boronated membrane of a model cell and as the
reaction fragments (alpha and Li) traverse into the cellular nucleus.
Methods and Materials: The present microdosimetry calculation is base
d upon the assumption that the therapeutic advantage of boron neutron
capture therapy (BNCT), while depending upon the RBE and LET of the re
action particles, is equally dependent on the boron carrier preferenti
al localization to tumor tissue, and the boron selectivity to cancerou
s cells and its specificity within subcellular compartments. In partic
ular, boron fixes to cell membrane as it ought to, using monoclonal an
tibodies. The present Monte Carlo simulation computes stochastic expec
tations of alpha/Li energy depositions to the nucleus in a uniformly b
oronated membrane shell of a spherical cell. Differential energy gain
was deduced from the stochastic energy depositions in events of neutro
n reactions with membrane boron compared against those with natural el
ements (O, H, N) in the cell. Results: Microdosimetry data are present
ed in terms of specific energy (keV/mu(3)) and lineal energy (keV/mu)
functions of the nucleus-to-cell volume ratios (NCVR). When folded wit
h the geometric boron content and accounting for background reaction e
nergies, the distributions yield effective energy gain to the cell nuc
leus per neutron capture event. Boron amount required to yield these e
nergy gains are found to be of the order of picograms of boron per gra
m of cell mass. Conclusion: The boron content as inferred by the prese
nt Monte Carlo microdosimetry compares well with that deliverable by p
resent pharmacokinetic means, but are orders of magnitude (mu-grams) l
ess than those deduced previously from anthropomorphic macrodosimetry.