A Monte Carlo study of SPECT in boron neutron capture therapy for a heterogeneous human phantom

Background: boron neutron capture therapy (bnct) is a binary radiotherapycombining biochemical targeting with neutron irradiation. however, monitoring theboron distribution is a fundamental problem in bnct. prompt gamma rays emiedby boron capture reaction can be used to address the issue. materials andmethods: the general-purpose monte carlo toolkits geant4 and mcnp were usedfor the simulations. a cubic phantom with so) tissue was used to study the promptgamma emission during bnct. the chinese hybrid phantom with arbitrary tumorswas constructed and used to acquire the 0.478 mev prompt gamma rays in bnct.tomographic images were reconstructed with the maximum likelihood expectaonmaximization (mlem) algorithm. results: comparison between mcnp andgeant4 showed a similar gamma rays emission rate in so) tissue. up to 30gamma ray peaks were found in the simulation, and 0.478 mev promptgamma ray from boron was clearly observed. the single brain tumor withvariable diameter from 1 cm to 4 cm in the heterogeneous anthropomorphicphantom was each time found to be recognizable in the reconstructed image.furthermore, in a pattent with four tumors, the variable distance between thesource and the tumors leads to a neutron attenuation thus resulng in aninhomogeneous number of prompt gammas. conclusion: the spect system fora heterogeneous phantom in bnct was simulated with geant4. the results showthat bnct-spect is valid for the reconstrucon of the boron capture interaconposion for a heterogeneous paent.