A method for fast evaluation of neutron spectra for BNCT based on in-phantom figure-of-merit calculation.
In this paper a fast method to evaluate neutron spectra for brain BNCT is developed. The method is based on an algorithm to calculate dose distribution in the brain, for which a data matrix has been taken into account, containing weighted biological doses per position per incident energy and the incident neutron spectrum to be evaluated. To build the matrix, using the MCNP 4C code, nearly monoenergetic neutrons were transported into a head model. The doses were scored and an energy-dependent function to biologically weight the doses was used. To find the beam quality, dose distribution along the beam centerline was calculated. A neutron importance function for this therapy to bilaterally treat deep-seated tumors was constructed in terms of neutron energy. Neutrons in the energy range of a few tens of kilo-electron-volts were found to produce the best dose gain, defined as dose to tumor divided by maximum dose to healthy tissue. Various neutron spectra were evaluated through this method. An accelerator-based neutron source was found to be more reliable for this therapy in terms of therapeutic gain than reactors.
Martín
Guido
G
Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear, 5ta y 30, Miramar, Playa, PO Box 6122, Ciudad Habana, Cuba. guido@ceaden.edu.cu
D000465:Algorithms; D016754:Boron Neutron Capture Therapy / Q000295:instrumentation / Q000379:methods*; D001921:Brain / Q000503:physiopathology; D001932:Brain Neoplasms / Q000532:radiotherapy*; D006257:Head / Q000503:physiopathology; D006801:Humans; D019047:Phantoms, Imaging; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*