Figure 1

Comparison between conventional CT and PET-CT image. A: By conventional CT, it was difficult to distinguish the boundaries between incompletely expanded lung tissue and tumor tissue with consequent excessive target delineation. B: By PET-CT, the areas of high metabolic activity indicated the presence of tumors. The target volume was obviously smaller than that on conventional CT image. C: On conventional CT image, the mediastinal lymph node had a short-axis diameter of 4.36 mm and was not considered a metastatic lymph node. D: On PET-CT image, the mediastinal lymph node showed high metabolic activity and was considered a metastatic lymph node.