Premium
Combined use of FLUKA and MCNP‐4A for the Monte Carlo simulation of the dosimetry of 10 B neutron capture enhancement of fast neutron irradiations
Author(s) -
Pignol JeanPhilippe,
Cuendet Pascal,
Brassart Nicole,
Fares Georges,
Colomb Florence,
M'Bake Diop Cheikh,
Sabattier Roland,
Hachem Ahmed,
Prevot Gilles
Publication year - 1998
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598264
Subject(s) - neutron , neutron temperature , thermoluminescent dosimeter , neutron flux , dosimetry , dosimeter , monte carlo method , materials science , nuclear physics , neutron capture , physics , beryllium , radiochemistry , radiation , nuclear medicine , chemistry , medicine , statistics , mathematics
Boron neutron capture enhancement (BNCE) of the fast neutron irradiations use thermal neutrons produced in depth of the tissues to generate neutron capture reactions on10 B within tumor cells. The dose enhancement is correlated to the10 B concentration and to thermal neutron flux measured in the depth of the tissues, and in this paper we demonstrate the feasibility of Monte Carlo simulation to study the dosimetry of BNCE. The charged particle FLUKA code has been used to calculate the primary neutron yield from the beryllium target, while MCNP‐4A has been used for the transport of these neutrons in the geometry of the Biomedical Cyclotron of Nice. The fast neutron spectrum and dose deposition, the thermal flux and thermal neutron spectrum in depth of a Plexiglas phantom has been calculated. The thermal neutron flux has been compared with experimental results determined with calibrated thermoluminescent dosimeters (TLD‐600 and TLD‐700, respectively, doped with6 Li or7 Li ). The theoretical results were in good agreement with the experimental results: the thermal neutron flux was calculated at10.3 × 10 6 n / cm 2 s 1and measured at9.42 × 10 6 n / cm 2 s 1at 4 cm depth of the phantom and with a 10 cm × 10 cm irradiation field. For fast neutron dose deposition the calculated and experimental curves have the same slope but different shape: only the experimental curve shows a maximum at 2.27 cm depth corresponding to the build‐up. The difference is due to the Monte Carlo simulation which does not follow the secondary particles. Finally, a dose enhancement of, respectively, 4.6% and 10.4% are found for 10 cm × 10 cm or 20 cm × 20 cm fields, provided that 100 μg/g of10 B is loaded in the tissues. It is anticipated that this calculation method may be used to improve BNCE of fast neutron irradiations through collimation modifications.