The first reported case of a patient with small cell lung cancer treated with fan beam computed tomography-guided online adaptive radiotherapy

Adaptive radiotherapy (ART) allows control of dosimetric impact of patient anatomical and functional variations over the treatment course, to minimize normal tissue exposure and maximize dose delivery to tumor. We present the first reported case of fan beam computed tomography (FBCT)-guided online ART for the treatment of small cell lung cancer (SCLC). A 62-year-old woman was diagnosed with histologically proven limited-stage SCLC. During definitive radiochemotherapy (50 Gy in daily fractions of 2.5 Gy), the tumor shrinkage resulted in an unexpected dose escalation to organs at risk (OAR). To correct the dose change, she received an online ART treatment session in our center with four-dimensional FBCT before the 12th fraction was delivered. The application of online ART, including imaging, recontouring and replanning, was feasible as the total treatment time was