In phantom Dosimetry for Boron Neutron Capture Therapy (BNCT)

G. GAMBARINI M. CARRARA S. GAY M. VALENTE

Bruxels; Belgium

Congreso; International Conference on Radioisotopes; 2005

In-phanom measurements of physical dose distributions are very important for BNCT planning validation. During exposure to thermal or epithermal neutrons, the absorbed dose in tissue is released by the various components of secondary radiation. Therefore, it is necessary to determine the spatial distributions of the absorbed dose, separating the various contributions, because they have dissimilar biologic effect. The spatial trends of the different dose components and their relative contributions in each position depend on the beam geometry and also on the size and shape of the irradiated volume. Gel dosimeters have demonstrated to be able to image the dose distribution of each radiation component. The measured doses are. (a) the gamma dose, due to gamma rays induced by thermal neutron reactions with hydrogen in the tissue itself and with various isotopes in the structures around the beam.; (b) the neutron dose, mainly due to recoil protons owing to scattering reactions of epithermal and fast neutrons; (c) dose from protons emitted in reactions of thermal neutrons with nitrogen; (d) dose due to á particles and 7Li ions emitted in 10B(n,á)7Li reactions; (e) electron dose in the case of presence of 157Gd; in fact, the gamma rays emitted in the reaction 157Gd(n,ã) are measured together with those of point (a), and the dose due to internal conversion and Auger electrons is imaged separately. A method has been settled for achieving the dose images in phantoms also having suitable non-homogeneity, well fitting neutron transport conditions. The proposed technique for in-phantoms dose imaging and profiling utilizes gel dosimeters in form of layers, imaged with an optical method by means of a CCD camera. A method for dose mapping, and for separating the contributions of the secondary radiation, with thermoluminescent dosimeters (TLD) has been developed too. Fluence measurements with activation techniques and Monte Carlo simulations are performed in order to confirm the reliability of the methods.á particles and 7Li ions emitted in 10B(n,á)7Li reactions; (e) electron dose in the case of presence of 157Gd; in fact, the gamma rays emitted in the reaction 157Gd(n,ã) are measured together with those of point (a), and the dose due to internal conversion and Auger electrons is imaged separately. A method has been settled for achieving the dose images in phantoms also having suitable non-homogeneity, well fitting neutron transport conditions. The proposed technique for in-phantoms dose imaging and profiling utilizes gel dosimeters in form of layers, imaged with an optical method by means of a CCD camera. A method for dose mapping, and for separating the contributions of the secondary radiation, with thermoluminescent dosimeters (TLD) has been developed too. Fluence measurements with activation techniques and Monte Carlo simulations are performed in order to confirm the reliability of the methods.á)7Li reactions; (e) electron dose in the case of presence of 157Gd; in fact, the gamma rays emitted in the reaction 157Gd(n,ã) are measured together with those of point (a), and the dose due to internal conversion and Auger electrons is imaged separately. A method has been settled for achieving the dose images in phantoms also having suitable non-homogeneity, well fitting neutron transport conditions. The proposed technique for in-phantoms dose imaging and profiling utilizes gel dosimeters in form of layers, imaged with an optical method by means of a CCD camera. A method for dose mapping, and for separating the contributions of the secondary radiation, with thermoluminescent dosimeters (TLD) has been developed too. Fluence measurements with activation techniques and Monte Carlo simulations are performed in order to confirm the reliability of the methods.ã) are measured together with those of point (a), and the dose due to internal conversion and Auger electrons is imaged separately. A method has been settled for achieving the dose images in phantoms also having suitable non-homogeneity, well fitting neutron transport conditions. The proposed technique for in-phantoms dose imaging and profiling utilizes gel dosimeters in form of layers, imaged with an optical method by means of a CCD camera. A method for dose mapping, and for separating the contributions of the secondary radiation, with thermoluminescent dosimeters (TLD) has been developed too. Fluence measurements with activation techniques and Monte Carlo simulations are performed in order to confirm the reliability of the methods.