| Abstract [eng] |
Radiation shielding in LINAC head with lead free and polymer composite materials has drawn attention in the medical physics field. An effective two stage shielding approach is needed, including the moderation of fast neutrons into thermal neutrons, followed by the absorption of thermal neutrons and high-energy photon radiation. HDPE is recognized as an effective neutron moderator due to its high hydrogen content, which effectively slows- down fast neutron through elastic scattering. On the other hand, Gd2O3 has strong attenuation capability for both thermal neutrons and photons, owing to its high neutron capture cross section and its effectiveness in photon interactions such as the photoelectric effect and Compton scattering. Therefore, this report aims to investigate the shielding performance of 3D printed HDPE composites reinforced with Gd2O3. Three types of filaments, HDPE, HDPE/5 wt% Gd2O3, and HDPE/10 wt% Gd2O3 were successfully produced using a 3Devo Precision filament extruder, and corresponding samples were fabricated with a Creality K2 Plus 3D printer. The produced filaments were used to print cylindrical samples with a diameter of 20 mm and a thickness of 5 mm, and the test specimens - ISO 527-2 type 1BA for attenuation test and tensile test, respectively. A Pu-Be mixed field radiation neutron source with a neutron flux 6.85×104 n/cm2/s was used for sample irradiation, which was performed at the Center of Physical and Technological Sciences, Department of Nuclear Research. The attenuation properties, including mean neutron transmission and attenuation percentage values, were analyzed using GafchromicTM EBT3 film as dosimetry tool for data collection. A universal testing machine (UTM) Tinius Olsen H25 KT (Tinius Olsen, Horsham, United States), was used to test mechanical properties of 3D printed composites. The obtained results indicate that 3D-printed HDPE/Gd2O3 composite structures with different filler concentrations may be promising candidates for the development of lightweight, lead-free shielding materials against mixed radiation fields, including neutrons and photons. Such materials could be particularly relevant for localized shielding applications in medical linear accelerator heads, where photoneutron production requires compact and adaptable radiation protection solutions. |
