The poor prognosis in the early-stage of lung cancer is due to potential worsening of the disease (local relapse, metastasis), to insufficient efficacy and toxicity of actual treatments.

FDG-PET is a medical imaging modality allowing the quantification of the tumour glucose consumption. Then, this exam is used for pathology staging, target volume definition for RT, and treatment efficiency few months after RT or CRT. Our assumption is that an FDG-PET exam during the course of the RT or CRT might be predictive of the treatment efficiency few months later.

In this study, the investigators propose to perform 4 FDG-PET: first "PET1" before radiotherapy, second "PET2" during the radiotherapy (see RTEP1), third and fourth "PET3" "PET4" 3month and 12 month after the therapy.

The investigators will investigate the performances of FDG-PET performed during the RT or CRT for the prediction of the one-year patient heath outcome. If the predictive value of TEP2 is confirmed, the investigators would be able to optimize the planning treatment during the course of the therapy.

Inclusion Criteria:

• Histologically confirmed non-small cell lung cancer
• Fertile patients must use effective contraception
• WHO performance status <2
• Measurable disease, defined as at least one lesion that can be accurately measured in at least one dimension (≥ 10 mm with spiral CT scan)

Exclusion Criteria:

• Pregnant or lactating females
• Baseline fludeoxyglucose F 18 (FDG)-positron emission tomography (PET) scan without any target lesion
• Unable to under PET CT evaluation
• other concurrent investigational agents
• No Planning to undergo curative intent radiotherapy
• familial, social, geographic, or psychological conditions that would preclude study participation
• Prior malignancy progressive disease