Imaging of gamma and neutron dose distributions at LVR-15 epithermal beam by means of FGLDs.

Gamma and fast neutron dose spatial distributions have been measured at the collimator exit of the epithermal neutron beam of LVR-15 reactor (Rez). Measurements were performed by means of optically analyzed Fricke-gel-layer detectors. The separation of the two dose contributions has been achieved by suitable pixel-to-pixel elaboration of the light transmittance images of Fricke-gel-layer detectors prepared with water and heavy water.

Polymer gels for in-phantom dose imaging in radiotherapy.

Normoxic polymer gel dosimeters are studied, with the aim of achieving a valid and advantageous method for in-phantom 3D dose determinations. Developments were carried out in the application of such dosimetric material to the method based on dosimeter gel layers that has shown good reliability for absorbed dose imaging in radiotherapy. The technique has been improved, in particular taking care of minimizing the oxygen infiltration into the gel matrix in order to suitably avoid its effect of inhibiting the polymerization process after exposure. A suitable choice of the material of dosimeter walls has brought to achieve good steadiness in time of dosimeter sensitivity and satisfactory results in dose imaging and depth-dose profiling.

Dose imaging in a thorax phantom with lung-equivalent volume at the epithermal neutron beam of LVR-15 reactor.

A thorax phantom has been designed, consisting of PMMA and PE plates containing a cavity filled with a laboratory-made lung-substitute. Fricke-gel dosimeters have been placed in the lung-substitute volume, and the phantom has been irradiated at the epithermal column of LVR-15 reactor. Absorbed dose images have been obtained for both gamma radiation and charged particles emitted in the (10)B reactions with thermal neutrons. Measurements with thermoluminescence dosimeters (TLDs) and Monte Carlo (MC) calculations have been performed too, in order to attain inter-comparison of results.

In-phantom dose imaging with polymer gel layer dosimeters.

Gel dosimeters in form of layers have shown noticeable potentiality for in-phantom dose profiling and imaging in BNCT neutron fields. Such dosimeters give the possibility of achieving spatial dose distributions of each dose contribution in neutron fields. The various dose components are separated by means of pixel-to-pixel manipulations of pairs of images acquired with gel dosimeters having different isotopic compositions. The reliability of polymer-gel-layer dosimeters (PGLD) for BNCT has been studied and their utilisation limits have been inspected.

Gel dosimetry in the BNCT facility for extra-corporeal treatment of liver cancer at the HFR Petten.

A thorough evaluation of the dose inside a specially designed and built facility for extra-corporeal treatment of liver cancer by boron neutron capture therapy (BNCT) at the High Flux Reactor (HFR) Petten (The Netherlands) is the necessary step before animal studies can start. The absorbed doses are measured by means of gel dosemeters, which help to validate the Monte Carlo simulations of the spheroidal liver holder that will contain the human liver for irradiation with an epithermal neutron beam. These dosemeters allow imaging of the dose due to gammas and to the charged particles produced by the (10)B reaction. The thermal neutron flux is extrapolated from the boron dose images and compared to that obtained by the calculations. As an additional reference, Au, Cu and Mn foil measurements are performed. All results appear consistent with the calculations and confirm that the BNCT liver facility is able to provide an almost homogeneous thermal neutron distribution in the liver, which is a requirement for a successful treatment of liver metastases.