Figure 4. Wire diagrams showing planning target volume (PTV) delineated from CT (yellow) and from CT + PET (red) for one non-small cell lung cancer patient. Involved paratracheal lymph nodes were detected on PET scan, which were subsequently incorporated into the patient PTV. Reprinted with permission of Elsevier from: Erdi YE, Rosenzweig K, Erdi AK, et al. Radiotherapy treatment planning for patients with non-small cell lung cancer using positron emission tomography (PET). Radiother Oncol 2002;62:51–60.