120: From bench to bedside: development and early clinical results of 188Re-SSS/Lipiodol for HCC treatment

Results: For 2x2x3mm3 crystals we achieve a CTR of 108±5ps FWHM at an energy of 511keV. Under the same experimental conditions an increase in crystal length to 5mm deteriorates the CTR to 123±7ps FWHM, 10mm to 143±7ps FWHM and 20mm to 176±7ps FWHM. This degradation in CTR is caused by the light transfer efficiency (LTE) and light transfer time spread (LTTS) in the crystal. To quantitatively understand the measured values, we developed a Monte Carlo simulation tool in MATLAB incorporating the timing properties of the photodetector and electronics, the scintillation properties of the crystal and the light transfer within the crystal simulated by SLITRANI. In this work, we show that the predictions of the simulation are in good agreement with the experimental data. We can also derive what is the best time estimator for the case of fully digital readout as a function of the SiPM characteristics, level of dark count noise and scintillation signal shape. Conclusions: Very good timing resolution has been obtained and the influence of the crystal length has been quantitatively assessed. Moreover these data allowed us to validate a very detailed Monte Carlo model that helps us now, by switching on and off the different contributions to understand their relative influence and to optimize the overall timing resolution. Future investigations will be on the role of photonic crystals to further improve these results.