Developement and evaluation of methods for comparison of dose distributions in radiotherapy using calculated, synthetic and simulated measured dose distributions

Abstract: ntensity modulated radiation therapy (IMRT) is becoming a more and moreused technique in radiation therapy. The main reason for this is that IMRT treament delivers a more conformal dose to the target together with a better sparing of organs at risk. Quality assurance of the generated IMRT treatment plan is of most importance to ensure that the patient recives the planned dose. Different methods exist for comparison of dose distributions where the gamma evaluation (Low et al. [19]) is the most commonly used. In this thesis different types of evaluation methods have been implemented in an evaluation software.Different types of known errors were introduce in an IMRT-plan (synthetic dose distribution). These synthetic dose distributions were then evaluated with a number of evaulation methods to identify what types of criterion needed to discover the introduced errors. A method for comparison of dose distributions with a statistical approach wasalso introduced and compared with the gamma evaluation method. A gamma criteria of 4% of the maximum dose and 4 mm in positioning is neededto discover all introduced errors. For the developed statistical evaluation method (χ2-test) the standard deviations needed to discover all errors were 1.5% of the maximum dose and 1 mm in positioning.