Interface Radiation Dosimetry in Mandibular Reconstruction

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Abstract
• When a beam of radiation crosses the interface between two substances, secondary electrons are generated. This results in enhancement of the absorbed dose of radiation roughly proportional to the difference in atomic numbers. interfaces are created in reconstruction of the mandible with implantable trays containing hematopoietic bone marrow and cancellous bone chips. Radiation was measured in tissue-equivalent material surrounding mandibular tray implants of titanium, vitallium, stainless steel, and Dacron/polyetherurethane. The absorbed dose was enhanced by 29% to 36% adjacent to the metallic trays; 1% dose enhancement was noted adjacent to the Dacron/polyetherurethane tray. We conclude that, when radiation therapy is necessary following mandibular reconstruction, homogeneity of dose is maintained and local soft-tissue reactions to excessive irradiation may be avoided by using a nonmetallic tray. (Arch Otolaryngol 105:293-295, 1979)