Cálculo de blindagem em medicina nuclear no Brasil: diretrizes, metodologia e avaliação do impacto do uso de fatores não usuais na espessura final

Abstract

Radiation shielding calculation reports are a legal requirement and a fundamental prerequisite for obtaining authorization for the construction and operation of nuclear medicine services in Brazil. Despite their regulatory and technical relevance, the national and international literature presents fragmented approaches, with gaps in the methodological organization of shielding calculations. This thesis is characterized as applied regulatory research, aiming to consolidate and structure an integrated methodology for radiation shielding calculations in nuclear medicine services, adapted to the Brazilian regulatory and operational context. The work is based on a critical compilation of the specialized literature, the analysis of consolidated references, and the practical application of the proposed methodology to representative scenarios, encompassing diagnostic and therapeutic environments, multiple dose contributions, and hybrid systems. Non-standard factors, often treated in a simplified manner in conventional methods, are discussed and evaluated, including the definition of the critical group, the customization of occupancy factors, the integrated consideration of multiple dose contributions, and the integration between different diagnostic modalities. It is demonstrated that decisions usually regarded as secondary may lead to significant variations in the final shielding thickness, affecting both radiological optimization and the technical and economic feasibility of projects, while maintaining compliance with dose limits established by regulations. The main contribution of this work lies in the compilation, organization, and critical systematization of concepts, parameters, and formulations already consolidated in the literature, reinterpreted in light of current national legislation and accumulated practical experience. By explicitly addressing underexplored factors and discussing their implications for shielding calculations, this thesis broadens the scope of traditional approaches and provides support for more realistic, context-aware designs aligned with the actual operating conditions of nuclear medicine services, while also serving as a technical reference for professionals in the field and for regulatory assessment.