Improvements in the treatment of rectal cancer patients have led to increased survival. Therefore, long-term outcome has become an increasingly important factor. Both neoadjuvant (chemo... Show moreImprovements in the treatment of rectal cancer patients have led to increased survival. Therefore, long-term outcome has become an increasingly important factor. Both neoadjuvant (chemo)radiotherapy and total mesorectal excision surgery are associated with toxicity. As a result, research for rectal cancer treatment has focused on the reduction of radiation dose to healthy tissue and less extensive surgery or omission of surgery in selected patients. The work described in this thesis can be used to reduce uncertainties related to image-guided external beam radiotherapy (EBRT) and high-dose-rate endorectal brachytherapy (HDREBT) of rectal cancer. By decreasing treatment related uncertainties, dose to surrounding healthy tissue can be reduced and/or a higher dose to the target volume can be delivered with an isotoxic effect. The MRI visibility of four types of fiducial markers as a surrogate for gross tumor volume (GTV) location was evaluated. In addition, it was found that the use of fiducial markers as a surrogate for GTV location in an EBRT GTV boost setting allows smaller treatment margins. For HDREBT, it was found that daily CT imaging should be the minimal standard to verify a correct applicator setup. In addition, we propose the use of an ultrashort echo time MRI sequence to visualize the applicator on MRI. Lastly, we determined the added value of a national study group meeting on the quality and variability of EBRT treatment plans for the introduction of a novel target volume that includes only the mesorectum. Show less
The past decade has provided many technological advances in radiotherapy. The European Institute of Radiotherapy (EIR) was established by the European Society of Therapeutic Radiology and Oncology ... Show moreThe past decade has provided many technological advances in radiotherapy. The European Institute of Radiotherapy (EIR) was established by the European Society of Therapeutic Radiology and Oncology (ESTRO) to provide current consensus statement with evidence-based and pragmatic guidelines on topics of practical relevance for radiation oncology. This report focuses primarily on 3D CT-based in-room image guidance (3DCT-IGRT) systems. It will provide an overview and current standing of 3DCT-IGRT systems addressing the rationale, objectives, principles, applications, and process pathways, both clinical and technical for treatment delivery and quality assurance. These are reviewed for four categories of solutions; kV CT and kV CBCT (cone-beam CT) as well as MV CT and MV CBCT. It will also provide a framework and checklist to consider the capability and functionality of these systems as well as the resources needed for implementation. Two different but typical clinical cases (tonsillar and prostate cancer) using 3DCT-IGRT are illustrated with workflow processes via feedback questionnaires from several large clinical centres currently utilizing these systems. The feedback from these clinical centres demonstrates a wide variability based on local practices. This report whilst comprehensive is not exhaustive as this area of development remains a very active field for research and development. However, it should serve as a practical guide and framework for all professional groups within the field, focussed on clinicians, physicists and radiation therapy technologists interested in IGRT. (C) 2010 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 94 (2010) 129-144 Show less
