18 F-FDG PET-CT Simulation for Non–Small-Cell Lung Cancer: Effect in Patients Already Staged by PET-CT

• Published in: International journal of radiation oncology, biology, physics Vol. 77; no. 1; pp. 24 - 30
• Main Authors: Hanna, Gerard G., M.B., M.R.C.P., F.R.C.R, McAleese, Jonathan, M.A., M.R.C.P., F.R.C.R, Carson, Kathryn J., Ph.D, Stewart, David P., M.B., M.R.C.P., F.R.C.R, Cosgrove, Vivian P., Ph.D, Eakin, Ruth L., M.B., F.R.C.P.I., F.R.C.R, Zatari, Ashraf, Ph.D, Lynch, Tom, M.B., F.R.C.R, Jarritt, Peter H., Ph.D, Young, V.A. Linda, D.C.R, O'Sullivan, Joe M., M.D., F.R.C.P.I., F.F.R.R.C.S.I, Hounsell, Alan R., Ph.D
• Format: Journal Article
• Language: English
• Published: 2010
• Subjects: Hematology, Oncology and Palliative Medicine; Radiology; computed tomography; lung cancer; target volume definition; radiotherapy planning; NSCLC; PET-CT; non–small-cell lung cancer; Positron emission tomography
• ISSN: 0360-3016
• DOI: 10.1016/j.ijrobp.2009.04.045

Purpose Positron emission tomography (PET), in addition to computed tomography (CT), has an effect in target volume definition for radical radiotherapy (RT) for non–small-cell lung cancer (NSCLC). In previously PET-CT staged patients with NSCLC, we assessed the effect of using an additional planning PET-CT scan for gross tumor volume (GTV) definition. Methods and Materials A total of 28 patients with Stage IA-IIIB NSCLC were enrolled. All patients had undergone staging PET-CT to ensure suitability for radical RT. Of the 28 patients, 14 received induction chemotherapy. In place of a RT planning CT scan, patients underwent scanning on a PET-CT scanner. In a virtual planning study, four oncologists independently delineated the GTV on the CT scan alone and then on the PET-CT scan. Intraobserver and interobserver variability were assessed using the concordance index (CI), and the results were compared using the Wilcoxon signed ranks test. Results PET-CT improved the CI between observers when defining the GTV using the PET-CT images compared with using CT alone for matched cases (median CI, 0.57 for CT and 0.64 for PET-CT, p = .032). The median of the mean percentage of volume change from GTVCT to GTVFUSED was −5.21% for the induction chemotherapy group and 18.88% for the RT-alone group. Using the Mann-Whitney U test, this was significantly different ( p = .001). Conclusion PET-CT RT planning scan, in addition to a staging PET-CT scan, reduces interobserver variability in GTV definition for NSCLC. The GTV size with PET-CT compared with CT in the RT-alone group increased and was reduced in the induction chemotherapy group.