Background: To determine the optimal approach to delineating patient-specific internal gross target volumes (IGTV) from four-dimensional (4-D) computed tomography (CT) image data sets used in the planning of radiation treatment for lung cancers.

Purpose-To characterize the relationship between radiation pneumonitis (RP) clinical symptoms and pulmonary metabolic activity on post-treatment [ 18 F]-fluorodeoxyglucose positron emission tomography (FDG PET).Methods-We retrospectively studied 101 esophageal cancer patients who underwent restaging FDG PET/CT imaging between 3 and 12 weeks after completing thoracic radiotherapy. The Common Toxicity Criteria version 3 (CTC3) was used to score RP clinical symptoms. Linear regression was applied to the FDG PET/CT images to determine the normalized FDG uptake versus radiation dose. The pulmonary metabolic radiation response (PMRR) was quantified as this slope. Modeling was performed to determine the interaction of PMRR, mean lung dose (MLD), and percentage of lung receiving greater than 20 Gy (V20) with RP outcomes.Results-Of the 101 patients, 25 had grade 0, 10 had grade 1, 60 had grade 2, 5 had grade 3, and 1 had grade 5 RP symptoms. Logistic regression demonstrated that increased values of both MLD and PMRR were associated with a higher probability of RP clinical symptoms (P=0.032 and P=0.033, respectively). Spearman's rank correlation found no association between the PMRR and dosimetric parameters (PTV, MLD, V5 through V30). Two-fold cross validation demonstrated the combination of MLD and PMRR was superior to either alone for assessing the development of Conflict of Interest Notification:The authors declare that they have no commercial or financial interests related to this study to disclose.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Conclusions-This study demonstrated a significant correlation between RP clinical symptoms and the PMRR measured by FDG PET/CT following thoracic radiotherapy. NIH Public Access

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Purpose The primary aim of this study was to quantitatively assess pulmonary radiation toxicity in patients who received thoracic radiotherapy combined with induction and/or concurrent chemotherapy with or without taxanes for esophageal cancer. Materials/Methods Subjects were 139 patients treated at The University of Texas M. D. Anderson Cancer Center for esophageal cancer and who had [18F]-fluorodeoxyglucose positron emission tomography/computed tomography imaging from November 1, 2003 to December 15, 2007, for disease restaging after chemoradiotherapy. Patients were grouped as having had (1) no taxanes, (2) induction or concurrent taxanes, and (3) both induction and concurrent taxanes. Clinical pulmonary toxicity was scored using the NCI Common Terminology Criteria for Adverse Events version 3. Linear regression was applied to the FDG uptake versus radiation dose to determine the pulmonary metabolic radiation response (PMRR) for each case. Clinical toxicity scores and PMRR among groups were evaluated for significance differences. Results The crude rates of pneumonitis symptoms were 46%, 62%, and 74% for groups 1, 2, and 3, respectively. The ANOVA test of log(PMRR) by treatment was significant (p=0.0046). Group 3 had 61% higher PMRR compared with group 1 (p=0.002). Group 2 had 38% higher PMRR compared with group 1 (p=0.015). Group 3 had 17% higher PMRR compared with group 2 (p=0.31). A PMRR enhancement ratio of 1.60 (95% CI: 1.19–2.14) was observed for group 3 versus group 1. Conclusions Patients given taxanes chemotherapy as induction and concurrent chemotherapy had significantly higher PMRR and clinical pneumonitis symptoms than did patients whose chemotherapy did not include taxanes.

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