Tehran University of Medical Sciences Frontiers in Biomedical Technologies 2345-5837 12 3 2025 07 01 509 518 Wrya Parwaie Department of Medical Physics, Faculty of Paramedical Sciences, Ilam University of Medical Sciences, Ilam, Iran Mikaeil Molazadeh Department of Medical Physics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran Tohid Mortezazadeh Department of Medical Physics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran Hosein Ghiasi Medical Radiation Research Team, Tabriz University of Medical Sciences. Tabriz. Iran. 2024 02 03 2025 03 15 Purpose: The purpose of this study was to estimate the dose enhancement of Gold, Silver, and Gadolinium on both microscopic and macroscopic scales in liver 177Lu nano-radionuclide therapy. Materials and Methods: The 177Lu radionuclide at the nano-scale was simulated using the MCNP 6.1 Monte Carlo (MC) simulation method. The emitted radiation characteristics, such as type and energy of emitted radiation, were modeled at the center of the tumor. The tumor cell (phantom liver) was filled with cubic voxels with sides of 1µm. These cubic voxels were then filled with GNP, AgNP, and GdNP spherical nanoparticles with a diameter of 30 nm each, and in a concentration of 10 mg/g of tissue. Results: The DEF was estimated at 5µm, 20µm, 50µm, 70µm, and 100µm from a single 177Lu nano-radionuclide radiation source at the center of the phantom liver cell, emitting both γ-ray and β- particles. A significant γ-ray DEF of up to 89% was observed at some µm around the source. Additionally, high DEF was derived for β- rays at some µm around the simulated radionuclides compared to greater distances.  Estimated DEF in tumoral tissue including GNP was 89%, 78%, 72%, 47%, and 25% at 5µm, 20µm, 50µm, 70µm, and 100µm respectively from the center. DEF for the other nanoparticles was also derived. Conclusion: A dramatic DEF was observed in the close vicinity of NPs around 177Lu as the radiation source, possibly due to the great gradient in dose and dominance of the photo-electric phenomenon. https://fbt.tums.ac.ir/index.php/fbt/article/view/935 https://fbt.tums.ac.ir/index.php/fbt/article/download/935/516