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Description
Breast cancer (BC) radiotherapy (RT) relies on accurate dose delivery to the target volume while minimizing exposure to surrounding healthy tissues. In preclinical research, however, access to dedicated small-animal irradiation platforms remains limited due to high costs, particularly in developing countries. This work presents the development and dosimetric validation of a low-cost lead body-shielding device for localized X-ray irradiation of BC-bearing mice. A custom cylindrical shielding system (7 × 14 × 1 cm; height × width × wall thickness), incorporating a 1 cm circular aperture for breast exposure was designed and coupled to a polymethyl methacrylate (PMMA) solid phantom (3.8 cm thickness) to simulate tissue-equivalent conditions. Dose measurements were performed using thermoluminescent (CaSO4) and optically stimulated luminescence (Al2O₃:C) dosimeters positioned at multiple depths and locations in the phantom to characterize dose distribution and attenuation. Irradiations were conducted using an X-ray source operating at 140 kV and 2.5 mA, with a source-to-surface distance of 27 cm. A calibration curve was generated to validate dose reproducibility and system performance. Dosimetric analysis demonstrated effective shielding, with dose attenuation of 72 ± 4% near the target margins, approximately 99 ± 2% along the body axis, and 82.0 ± 1.3% in the dorsal region. For biological validation, female BALB/c mice bearing BC tumors (~0.1 cm³) were positioned within the shielding device and irradiated for 20 min. Dosimeters at the tumor site indicated a delivered absorbed dose of 6.91 ± 0.20 Gy, in agreement with phantom-based measurements. Tumor growth analysis revealed significantly reduced tumor progression and relative tumor mass in irradiated animals compared to non-irradiated controls after 21 days of the irradiation. These results demonstrate that the proposed shielding device enables accurate, localized dose delivery, with substantial sparing of out-of-target tissue, representing a practical and cost-effective solution for preclinical RT studies.