Objective　　　 To establish an irradiation simulation model for monitoring dose of mediastinal lymph nodes in thoracic radiotherapy and provide the experimental basis for monitoring the actual dose of the lymph nodes in clinical setting.　　　 Methods　　　 Based on the standard height of Chinese men (height 170 cm

weight 65 kg)

20 male chest cancer patients with similar somatotype were recruited in this study. Varian’s Eclipse treatment planning system (TPS) was used to determine the three-dimensional positioning point of mediastinal lymph node distribution areas. The irradiation simulation phantom (hereinafter referred to as phantom) was drilled according to the positioning point and the three-dimensional data. Equipment for monitoring radiation dose was installed according to the shape and size of the radiation monitoring probe.　　　 Results　　　 The central points of the distribution areas in the mediastinal lymph nodes were accurately positioned using the Eclipse system. The average three-dimensional positioning data of standard Chinese men were measured on cross-sectional

sagittal and coronal planes of the chest CT images based on these accurate data. The phantom was accurately punched and the devices for monitoring radiation dose were installed

leading to the establishment of an irradiation simulation model for monitoring the dose of mediastinal lymph nodes.　　　 Conclusion　　　 An irradiation simulation model for monitoring dose of mediastinal lymph nodes in thoracic radiotherapy is established

which offering the accurate punching and installation of detection equipment. This model lays the foundation for the studies of dosimetry of thoracic radiotherapy.