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Hepatocellular carcinoma (HCC) accounts for more than 90% of primary liver tumors and is strongly associated with cirrhosis [1]. It is among the most incidental and lethal neoplasms worldwide, with low five-year survival rates due to late diagnosis and complex management. Risk factors include chronic viral hepatitis and alcoholic and metabolic liver diseases [2]. Hepatic radioembolization with $^{90}$Y is an established therapeutic alternative incorporated into international guidelines, especially for localized tumors [3]. This study evaluates dose distribution in $^{90}$Y treated liver tumors of different sizes using Monte Carlo simulations. The hepatic tumors and their vascular networks were modeled in Blender [4] with different volumes and positioned within the virtual male anthropomorphic phantom described in ICRP Publication 145 [5]. Simulations were performed in the TOPAS code [6], considering the radiation spectrum of $^{90}$Y, with the tumor and vessels acting as beta-emitting sources. Simulation results showed that, for a single tumor modeled as an $^{90}$Y emitting source, the progressive increase in tumor diameter resulted in a higher mean absorbed dose in the adjacent healthy liver tissues. However, despite tumor growth, dose deposition in surrounding organs remained low, limited by the short electron penetration range, indicating adequate spatial conformity even in scenarios with larger tumor volumes. It can be concluded that $^{90}$Y radioembolization provides a dose distribution predominantly confined to the tumor volume, maintaining low irradiation of adjacent organs even with increasing lesion diameter. Nevertheless, larger tumors imply higher exposure of healthy liver tissue.
[1] Mauro et al 2025 JHEP Rep 7 101571
[2] Amin et al 2025 Diseases 13 207
[3] Tong et al 2016 Br J Radiol 89 20150943
[4] Blender Foundation 2018 Blender
[5] Kim et al 2020 Ann ICRP 49 13-201
[6] Faddegon et al 2020 Phys Med 72 114–121