Validation of patient-specific metal 3D shielding block usability with GafChromic EBT3 film

Keloids are abnormal scars that result from excessive fibrous tissue proliferation during wound healing, with recurrence rates of 80–100% when treated with surgery alone. As a result, radiation therapy has become an essential adjunct treatment to reduce recurrence, with electron beam therapy demonstrating significant effectiveness. This study aims to optimize dose distribution in keloid radiotherapy using patient-specific shielding blocks and evaluate the radiation shielding performance of metal 3D shielding blocks fabricated through rapid prototyping as a potential alternative to conventional Cerrobend blocks. Monte Carlo simulations (GATE v8.0) and experimental validation using GafChromic EBT3 film were conducted for 6 MeV and 12 MeV electron beams to analyze the shielding efficiency of stainless steel 316L(SUS 316L), brass, and pure copper. The results confirmed that the fabricated metal 3D shielding blocks met the required transmission rate criteria (≤ 5%) and demonstrated strong agreement with Monte Carlo simulations. Pure copper exhibited excellent shielding performance with dosimetric characteristics comparable to Cerrobend, while brass showed superior mechanical strength, making it a promising material for long-term durability. Additionally, SUS 316L demonstrated excellent corrosion resistance and minimal deformation over repeated use, enhancing its clinical applicability. The difference between the off-axis and isodose curves of the cerrobend cutout and those of the metal prototypes was found to be minimal, indicating that the fabricated shielding blocks provided comparable dose distribution characteristics. The findings of this study suggest that metal 3D shielding blocks could serve as a viable alternative to conventional Cerrobend blocks, paving the way for personalized and precision radiation therapy. Further research is necessary to enhance mechanical durability, reduce radiation scattering, and develop lightweight shielding materials, ultimately improving the precision and efficiency of patient-specific electron beam therapy.