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Abstract

This work is dedicated to study the uncertainties occurring along the course of external beam radiation therapy. At first it was tested and assessed whether the quality of the detector systems used to analyze uncertainties, as well as the rationale to decide if a plan is acceptable or not, is sufficient. The angular dependency was investigated for the selected detector system and a compensation method is proposed. The capability of selected TPS to create reproducible treatment plans in clinical conditions was examined as well by applying multiple definitions of complexity metrics. A major part of this thesis was dedicated to introduce two new complementary software tools to be used with TomoTherapy units. These tools allow users to identify the leading causes for treatment failures using the built-in detector systems. Furthermore, we illustrate how these tools can be implemented in an adaptive radiotherapy framework by using their information to assess machine output and anatomical changes together with their dosimetry influence on the therapy outcome of a single fraction or cumulatively. Such methodical studies of the occurring uncertainties and their implications contribute substantially to the quality of treatments in radio-oncology centers.