Gel Dosimeters as Useful Dose and Thermal-fluence Detectors in Boron Neutron Capture Therapy (BNCT)

Gel dosimetry applications for detecting absorbed dose or thermal neutron fluence images in neutron fields suitable for BNCT have been widely investigated. Dosimeter analysis is based on visible light transmittance imaging by means of a CCD camera. Acceptable results have been obtained with Fricke-gel dosimeters, in which the measurable effect produced by ionising radiation is a change in the wavelength of light absorbance. Some studies are presently carried out concerning polymer-gel dosimeters, in which ionising radiation produces a polymerisation effect with consequent increase of the opacity of the medium. In both cases, results of light absorbance results can be linearly correlated to the absorbed dose. Polymer-gel dosimeters are still in a first phase of experimentation. Nevertheless, good reliability has been achieved with Fricke-gel dosimeters, after an extended work of optimisation of the protocols for dosimeter preparation, light transmittance detection and image manipulation. Dosimeters consist of layers of gel, 3 mm thick, placed between two transparent polystyrene sheets and contained in a thin frame having suitable shape and dimensions, depending on the specific measurement requirement. In the high fluxes of thermal/epithermal neutrons utilised for BNCT, such dosimeters have shown to be very advantageous for performing beam control and in-phantom dose verification, because they can get information that cannot be obtained with other methods. In fact, the usual imaging techniques, as those making use of gafchromic films, cannot be utilised in such neutron fields owing to the resulting activation of materials. Moreover, the important goal of separating the contributions of the various dose components was successfully achieved with gel dosimeters, in spite of their low sensitivity to high LET radiation. Some results obtained for testing the potentiality of Fricke-gel dosimeters for both checking an epithermal neutron field and imaging the in-phantom thermal neutron flux are here presented.

MOSS Raymond;  MARIANI M.;  CARRARA Mauro;  DAQUINO Giuseppe Giovanni;  NIEVAART Victor Alexander;  VALENTE Mauro;  VANOSSI Elena; 

GAMBARINI Grazia; 

2008-01-25

TAYLOR & FRANCIS LTD

JRC34195

1042-0150,   

https://publications.jrc.ec.europa.eu/repository/handle/JRC34195,   

10.1080/10420150701482667,