ESTRO 2023 - Abstract Book

S639

Monday 15 May 2023

ESTRO 2023

in a BNCT scenario, we have performed measurements inside the Prompt Gamma Neutron Activation Analysis (PGNNA) facility of TRIGA Mark II (Pavia, Italy). Vials filled with increasing concentration of 10B, down to 62 ppm, have been irradiated with thermal neutron fluxes of the order of 105 n/cm^2/s. To verify the imaging capabilities of the detector we have used a square crystal with a small thickness of 20 mm instead of the cylindrical one. The crystal surface has been scanned with a 1 mm 137Cs collimated source (662 keV). The SiPMs signals patterns have been used to train a Convolutional Neural Network (CNN). A dedicated collimator has been designed and it is currently under construction. Results The good energy resolution of the detector (2.7% FWHM at 662 keV) has allowed to identify the BNCT photopeak at 478 keV despite the huge background. The number of detected events under the peak at 478 keV has been found to increase linearly with the boron concentration of the vials irradiated.

Regarding the position sensitivity, the accuracy of the CNN has been found to be about 65% for both the reconstruction of the x and y and 90% if including also the adjacent pixels. The measurements have shown also a spatial resolution of the reconstructed position of 3.6 mm.

Conclusion It has been demonstrated the feasibility of our detection module for the development of a BNCT-SPECT system. Real BNCT measurements with a clinical neutron flux and the designed collimator are foreseen.

OC-0773 Correcting medical range fiber Bragg gratings dosimeter temperature dependencies