Determination of the Radial Dose Function, Anisotropy Function and Anisotropy Constant for the First 103Pd Seed Manufactured at AMIRS Using TLD-100

Brachytherapy sources of 103Pd with low photon energies are being used for interstitial implants in prostate tumors. Dosimetric parameters of these sources such as air kerma strength, dose rate constant, geometry function, radial dose function and anisotropy function should be calculated and measured accurately according to the recommendations of American Association of Physicists in Medicine (AAPM) addressed in TG-43U1 protocol. The first type of 103Pd brachytherapy seeds have been manufactured at Agricultural, Medical and Industrial Research Institute (AMIRI)- Atomic Energy Organization of Iran. Therefore, it is necessary to determine the TG-43U1 dosimetric parameters before clinical implementation.In this work, the radial dose function, anisotropy function and anisotropy constant for the first 103Pd seed manufactured at AMIRS have been determined using TLD-100 dosimeters. The TLD having dimensions of 3.1 ×3.1×0.9 mm3 were calibrated using 60Co radiation field. The TLD measurements were preformed in 30×30×30 cm3 Perspex phantoms in order to provide full scattering conditions. In this work, two phantoms were designed. The first phantom was used for the experimental determination of radial dose function and the second one was used for the experimental determination of anisotropy function. Dose distribution around the source was measured by TLD-100 dosimeters using RMKL KFKI reader. The radial dose function, anisotropy function and anisotropy constant of the first AMIRI 103Pdwereseed determined according to TG-43U1 recommendations. The obtained result was in good agreement with the results published by Meigooni et al for Best double-walled model 103Pd source.Discussion and The spatial dose distribution around the source and dosimetric parameters determined in this work showed that in dosimetry point of view, the new model 103Pd source manufactured at AMIRI is suitable for use in brachytherapy of prostate cancer.