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Radiotherapy plays a crucial role in cancer treatment and is applied to about half of all patients. An important innovation is the MR-linac, a device that combines magnetic resonance imaging (MRI) with a linear accelerator. This system enables precise visualization of tumors and surrounding tissues during treatment, allowing daily variations to be incorporated directly into the treatment plan. This is known as adaptive radiotherapy. In addition to imaging before treatment, the MR-linac can also acquire images during irradiation to track tumor motion, enabling techniques such as beam gating and intra-fraction drift correction.
 

To ensure accuracy of these treatments, quality assurance procedures are performed, including End-to-End (E2E) tests in which the full workflow is simulated. This thesis investigates the accuracy of MR-linac workflows using different measurement approaches.
Chapters 2 and 3 describe the evaluation of a plastic scintillation detector and a Delta4 phantom, which enabled time-resolved dosimetry. In Chapter 4, a motion platform was characterized that integrates motion into dosimetric measurements.
In Chapter 5, 3D gel dosimeters were used for E2E testing of inter-fraction adaptive workflows. These showed excellent geometric and dosimetric accuracy and provided volumetric information not available with 1D and 2D dosimeters. Chapter 6 introduced a new approach for testing intra-fraction workflows with motion management, demonstrating that reference dose distributions including motion are essential for reliable accuracy assessment.
 

Finally, Chapter 7 explored the feasibility of log file–based dose reconstructions. These calculations showed good agreement with measured distributions and hold promise as a tool for patient-specific quality assurance of motion-integrated treatments.