FIGURE 3. Example of software fusion of ¹⁸F-FDG PET and CT images of primary non–small cell lung cancer with lymph node metastasis in mediastinum for IMRT field planning. Patient was scanned for both ¹⁸F-FDG PET and CT on flat scanning bed, with arms up in rigid customized support system to minimize positioning differences. CT images were acquired during free tidal breathing, accounting for huge artifacts. ¹⁸F-FDG PET images were also acquired during free tidal breathing but show much more reliable delineation of tumor tissue. (A) Transverse slice. (B) Coronal slice.