In Boron Neutron Capture Therapy the discrimination of the different contributions to the absorbed dose in tissue is fundamental, owing to the different biological effectiveness of the emitted radiation. In a cylindrical phantom simulating a head, exposed to a thermal neutron flux from the fast-flux research reactor TAPIRO (located at the ENEA Casaccia Center near Rome), we have imaged the therapy dose from thermal neutron reactions with 10B and the dose in healthy tissue not containing boron.Our technique allows the measurement of the 3-D distribution of absorbed dose: it is based on a chemical dosimeter (ferrous sulphate solution) incorporated in a tissue-equivalent gel (Agarose). In a ferrous sulphate solution, which is the main component of the standard Fricke dosimeter, the chemical reactions occurring after exposure to ionising radiation give rise to oxidation of ferrous ions Fe2+ to ferric ions Fe3+ and the ferric ion yield is proportional to the absorbed dose. By incorporating in the dosimeter-gel a metal ion indicator (Xylenol Orange), it is possible to determine the absorbed dose through optical absorption measurements. We have set up a fast and practical method for dose imaging of such gel phantoms with a CCD camera. From differential measurements in phantoms having different gel compositions, exposed to the same neutron field, we have imaged the different contributions.The imaging results have been compared with the results obtained with other experimental techniques.
|Titolo:||Discrimination of Various Contributions to the Absorbed Dose in BNCT: Fricke-Gel Imaging and Intercomparison with other Experimental Results and Simulations|
|Data di pubblicazione:||3-ott-1999|
|Appare nelle tipologie:||4.1 Contributo in Atti di convegno|