RESUMO
The near threshold (7)Li(p,n)(7)Be neutrons generated by incident proton energy having Gaussian distribution with mean energies from 1.85 to 1.95MeV, were studied as a practical neutron source for BNCT wherein an RFQ accelerator and a thick Li-target are used. Gaussian energy distributions with the standard deviation of 0, 10, 20 and 40keV for mean proton energies from 1.85 to 1.95MeV were surveyed in 0.01MeV increments. A thick liquid Li-target whose dimensions were established in our previous experiments (i.e., 1mm-thick with 50mm width and 50mm length) was considered in this study. The suitable incident proton energy and physical dimensions of Pb layer which serves as a gamma absorber and a Polyethylene layer which is used as a BDE were surveyed by means of the concepts of TPD. Dose distribution were calculated by using MCNP5. A proton beam with mean energy of 1.92MeV and a Gaussian energy distribution with a standard deviation of 20keV at a current of 10mA was selected from the viewpoint of irradiation time and practically achievable proton current. The suitable thicknesses of Pb gamma absorber was estimated to be about 3cm. The estimated thickness of the polyethylene BDE was about 24mm for an ideal proton current of 13mA, and was 18mm for a practical proton current of 10mA.
Assuntos
Berílio/química , Terapia por Captura de Nêutron de Boro/instrumentação , Lítio/química , Modelos Estatísticos , Nêutrons/uso terapêutico , Aceleradores de Partículas/instrumentação , Absorção de Radiação , Berílio/efeitos da radiação , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Lítio/efeitos da radiação , Teste de Materiais , Distribuição Normal , Prótons , Radiometria , Dosagem Radioterapêutica , Espalhamento de RadiaçãoRESUMO
The feasibility of a pinhole camera system for online dosimetry in boron neutron capture therapy (BNCT) was studied. A prototype system was designed and built. Prompt γ-rays from the (10)B(n,α)(7)Li reaction from a phantom irradiated with neutrons were detected with the prototype system. An image was reconstructed from the experimental data. The reconstructed image showed a good separation of the two borated regions in the phantom. The counting rates and signal-to-noise ratio when using the system in actual BNCT applications are also discussed.
