Margriet Kwint

Chapter 1 16 thoracic and tumor volume changes collected during treatment on CBCT and its association with treatment outcome. In the last part of this thesis the prediction models of acute esophagus toxicity after CCRT are optimized. Part I Dose prescription and patient selection Subject of the studies in the first part of this thesis is optimizing the treatment of LA- NSCLC patients by adapting treatment dose prescription and execution. Since June 2015, patients with LA-NSCLC are treated in our institute with a differentiated dose to the primary tumor and involved mediastinal lymph nodes. Simultaneously, the planning margins for both the primary tumor and the lymph nodes are reduced. We also changed the patient selection by treating patients with oligometastatic disease with a radical irradiation scheme. In chapter 2, the treatment outcome of the dose de-escalation and margins reductions to the lymph nodes and the effects on the incidence of toxicities of this dose de-escalation are studied in a large retrospective cohort. In chapter 3, the PFS and OS of oligometastatic NSCLC patients selected for a treatment with radical intent are described. Part II Image Guided Radiotherapy With the increasing use of image guided radiotherapy for NSCLC patients, longitudinal imaging data of tumor volume reduction during the course of a radiotherapy treatment is available and intra thoracic anatomical changes are frequently detected. In chapter 4, the incidence of the different intra thoracic anatomical changes detected on CBCT during radiotherapy is described and a practical decision support system is introduced. In chapter 5, the association of tumor volume changes, detected on CBCT during concurrent chemoradiation for LA-NSCLC patients, with treatment outcome is studied.