الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Forty six patients with non small cell lung cancer were prospectively enrolled in this study. All patients treated with 3D-conformal radiotherapy (3D-CRT) and received 66 Gy in 33 fractions. PET/CT scan before the start of radiation and during the course of radiotherapy (either in weeks 1, 3, 5 or in weeks 2, 4, 6), every 3 months in the first year post-treatment, then every 6 months afterwards were performed. Only 13 patients developed radiation pneumonitis (RP). Mean SUV of the normal lung and in areas of radiological changes were evaluated and compared at different timepoints during- and post-radiotherapy. The CT density (mean HU) was also measured in these regions in all CTs. Different dose regions were defined and the mean SUVs were calculated in these dose regions for each patient at each time points.
We found no difference in mean SUV- of the whole lung between patients with and without RP before radiotherapy. However, significant differences were found at 5-6 weeks during radiotherapy, and at 3-6 months after radiotherapy. On the other hand, there was no difference in the mean HU of the whole lung between the groups at different timepoints.
Regarding the changes of mean SUV over time, it was found that the mean SUV of whole lung increased significantly over baseline at 1-2 weeks, 5-6 weeks in patients with RP. Also, the mean SUV increased significantly with time in the expected regions of RP.
A significant association was found between the mean of the SUV of a certain dose region and the mean dose received by that region at different timepoints. Moreover, a significant correlation was found between the mean SUV in different dose regions at different timepoints and the CT density in the same dose regions at 3-6 months after treatment.