The study population will exist of patients with a histological diagnosis of NSCLC, stage T1, T2 or T3NO who are not fit for or who refuse surgery. A prospective data analysis will be performed on tumor response, potential acute and late toxicity and survival. A radiotherapy dose of 4x15Gy or 3x 20Gy will be given over 2 weeks with dynamic 3D-conformal arc therapy (Novalis TM)