Monte Carlo Simulation of Liver Dosimetry with Yttrium-90 Radionuclide Using Gate: 3D Phantom

This study is aimed to validate Y-90 dosimetry with MC simulation by comparing the TLD measurements results obtained in 3D liqid phantom (LP) and its monte carlo (MC) simulation. In the first step, tumor imitation was filled with 1900 mu Ci (70.3 MBq) amount of Tc-99m activity in LP. In addition, 24 thermoluminescence dosimetry chips (TLD-100) were placed in 8 different locations in the LP. The same measurement system was created in GEANT4 Tomography Emission Application (GATE version 8.1). DoseActor library was defined for 24 points instead of TLDs and doses were taken. In the second step, Y-90 with the amount of 2 mCi (74 MBq) activity and 27 DoseActor libraries were placed in tumor mimic and different locations in LP to calculate the dose distribution with GATE. GATE and TLD results for Tc-99m were compared for validation. The strong correlation coefficient was calculated between the instant absorbed dose rates obtained via TLD measurements and GATE calculations as R-2 = 0.994. At the Y-90 dosimetry, the highest, lowest and mean cumulative absorbed doses calculated by GATE for a half-life were found to be 1.166 x 10(2) +/- 3.907 x 10(-1), 5.440 x 10(1) +/- 2.597 x 10(-1), and 75.145 +/- 0.303 Gy in the tumor imitation, and 1.167 x 10(1) +/- 1.777 x 10(-1), 9.929 x 10(-5) +/- 6.905 x 10(-5), 1.169 +/- 0.019 Gy in the liver parenchymal tissue imitation, respectively. GATE program is considered to be a promising application in internal radionuclide dosimetry, based on linear correlation between TLD and GATE measurements in our study.