To Evaluate the Impact of PET/CT on Radiation Treatment Planning in Relation to Changes in GTV in Stage 3 NSCLC

Primary objectives of the study: 1.To determine the impact of PET/CT fusion on gross tumor volume ( GTV ) for primary(GTVP) and nodal (GTVN) disease for each patient by comparing GTV contours using two separate data sets. (A) GTVP CT+ ve and GTVN CT+ ve (B) GTVP PET+ve and GTVN PET +ve GTV will be measured and recorded in cubic centimeters for each volume. Secondary Endpoints: 1.Normal tissue toxicity:3D conformal Computerized radiation plans will be generated for the data sets GTVP and GTVN A and B .Dose Volume Histogram (DVH) will be determined and compared for the following normal tissue toxicity parameters. I. V 20 Both lungs (Combined total lung volumes including PTV): Volume of both lungs receiving ≥ 20 G y, including planning target volume. II. Mean lung dose: Mean radiation dose received by both lungs in a given radiation plan, calculated by the planning computer. III. V 55 Esophagus: Volume of esophagus receiving≥ 55Gy. IV. Mean esophageal dose : Mean radiation dose received by whole esophagus in a given radiation plan, calculated by the planning computer V. Spinal cord dose: Maximum dose received by the spinal cord in a given radiation plan. V1.. V40 Whole heart: Volume of heart receiving ≥ 40Gy 2A Inter observer variation: This will be determined for the data sets GTV A and B only delineated by 4 radiation oncologists blinded to each other, for first 20 patients. The resident involved in this project will be responsible to co-ordinate this part of the project. GTV will be measured and recorded in cubic centimeters for each volume. 2B Intra observer variation: This will be determined for the data sets GTV A and B only delineated by the same radiation oncologist (treating physician) at two different occasions, for first 20 patients. Minimum time interval between the two contours will be one month .The resident involved in this project will be responsible to co-ordinate this part of the project. GTV will be measured and recorded in cubic centimeters for each volume.