Dose mapping of an irradiation chamber of a gamma cell unit using Fricke gel dosimeters and Monte Carlo simulation

A gamma cell unit is used for gamma irradiation of small volume samples. Due to the sample volume, there is a dose distribution, which is imperative to be known for appropriate irradiation. In this study, samples of agarose Fricke gel dosimeters were prepared for the dose mapping of the gamma cell unit available in our laboratory. To place the dosimeters at precise locations within the irradiation chamber of the gamma cell unit, a specific phantom was designed and fabricated. In this way, the dose distribution was estimated using optical absorbance measurement of the gel dosimeters. For verification, isodose curves were also obtained using Monte Carlo simulations. The results indicate that the central east-west and north-south points in the irradiation chamber have the highest and lowest dose values, respectively. The experimental and simulation ratios of the dose uniformity was calculated to be 1.53 and 1.48, respectively. The accuracy of the dosimeter performance and the system's calibration quality are confirmed by the good agreement between the simulation and experimental results.