ESTRO 2025 - Abstract Book

S2853

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2025

Purpose/Objective: Total body irradiation (TBI) requires lung shielding to prevent radiation-induced pneumonitis. Lung tissue is highly sensitive to radiation, and patients undergoing TBI are at significant risk of developing radiation-induced complications. Traditional methods using lead or Cerrobend blocks face challenges in achieving optimal patient specific shielding while being time and labor-intensive. This study evaluates the radiation transmission properties of 3D-printed bronze-polylactic acid (PLA) lung shields as an alternative, offering potential advantages in customization and workflow efficiency. Material/Methods: Measurements were conducted comparing transmission at standard (100 cm) and extended (425 cm) source-to-axis distances (SAD) using 6 MV and 15 MV photon beams from a linear accelerator (TrueBeam, Varian). An ionization chamber (CC13, IBA Dosimetry) was placed at a 10 cm depth within a solid water phantom (Solid Water HE, Sun Nuclear) to measure the dose transmitted through each shield type. The bronze-PLA shields (1.8 cm thick) were printed with 0.2 mm layer height and 100% infill density using filament containing approximately 60% bronze powder mixed with PLA. These printing parameters were optimized through preliminary testing to achieve maximum attenuation while maintaining structural integrity. Quality assurance included dimensional accuracy verification and uniformity testing.

Results: At the standard SAD of 100 cm, the bronze-PLA shields demonstrated transmission of 92.12 ± 0.03% for 6 MV beams compared to 86.43 ± 0.26% for lead/wax shields (P < 0.001, paired t-test). For 15 MV beams, transmissions were 94.88 ± 0.06% and 90.39 ± 0.05%, respectively (P < 0.001). Extended distance measurements showed similar trends, with bronze-PLA transmission at 91.91 ± 0.84% (6 MV) and 94.36 ± 0.30% (15 MV) versus lead/wax at 88.70 ± 0.33% and 91.38 ± 0.31%, respectively. Transmission uniformity across the shield surface showed less than 2% variation, indicating consistent manufacturing quality. Cost-efficiency analysis revealed that 3D-printed shields required 15 minutes of labor and $20-30 in materials, with 16-20 hours of automated printing time, compared to traditional shields requiring 1 hour of labor and $5-10 in materials.