LAUSR

PURPOSE Custom-fabricated lead shields are often used for superficial radiation treatments to reduce radiation doses to adjacent healthy tissue. However, the process for fabricating these lead shields is time-consuming, labor-intensive, and uncomfortable for patients. Alternatively, patient-specific shields can be 3D-printed from a high-density bronze-based filament to address these concerns. This study was performed to assess the shielding characteristics of 3D-printed bronze (3DPB) shields, demonstrate their clinical viability, and report the first ever published case of a patient treated with a 3DPB shield. METHODS AND MATERIALS The transmission of 6 and 9 MeV electron beams through varying thicknesses of 3DPB was first measured. Percent depth doses (PDD) and beam profiles were measured with flat 3DPB shields and equivalent lead shields to determine surface dose enhancement, output factors, and field widths. Two 3DPB shields were designed and fabricated for an anthropomorphic phantom, and phantom measurements were performed using optically stimulated luminescence dosimeters (OSLD) and film. Finally, 3DPB shields have been used during the treatment of seven patients' skin lesions. RESULTS 10 and 15 mm of 3DPB were sufficient to shield 6 and 9 MeV electrons by 95%, respectively. The 3DPB and lead shields had nearly identical beam widths (within 1%). Output factors were on average within 0.8% for bronze shields and 1.2% for lead shields relative to an unshielded field. The skin enhancement for bronze was higher than for lead by an average of 6.3%. Phantom measurements using 3DPB shields generally showed less than 3% transmission of the primary beam under the 3DPB shield. The patients' shields fit as designed and were all deemed clinically acceptable by their physicians. CONCLUSIONS The 3DPB shields fit better than lead shields, are easier to design and manufacture, and have similar dosimetric properties. 3DPB shields are a viable clinical option for patient-specific superficial shielding.