AbstractID: 11997 Title: Shielding Design for Linear Accelerators Using NCRP Report 151 The application of the structural shielding design techniques and goals as outlined in NCRP Report 147: Structural Shielding Design for Medical X-ray Imaging Facilities (November 2004) and NCRP Report 151: Structural Shielding Design and Evaluation for Megavoltage X- and Gamma-Ray Radiotherapy Facilities will be the basis for this practical course. Actual facility designs will be used as the example calculations of required shielding for Linear Accelerators to be installed in modern radiation therapy facilities. Examples of methods to minimize the amount of additional shielding needed for new departments due to well planned designs will be given. As the equipment in radiation oncology departments has evolved to linear accelerators with IMRT as state of the art modalities, the requirements for adequate radiation shielding for these modalities has become more rigorous. Architectural designs no longer depend on standard maze design rectangular rooms. Innovative layouts and utilization of multiple layers of shielding materials allow much greater flexibility in room designs. Shielding calculations for these challenging designs will be covered in this presentation. Educational Objectives: 1. Understand the workload and occupancy factors to be used for dual energy linear accelerators with IMRT capabilities to determine required structural shielding to meet exposure limits for occupational personnel and the public. 2. Understand the effectiveness of existing and additional structural shielding materials to provide radiation protection and methods to calculate the required amounts of these materials. 3. Understand the calculation methods to be used in performing the shielding calculations for all aspects of linear accelerator installations to insure adequate shielding is provided to meet applicable state and ALARA requirements.