27 March 2009 Validation of nonrigid registration for multi-tracer PET-CT treatment planning in rectal cancer radiotherapy
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Proceedings Volume 7259, Medical Imaging 2009: Image Processing; 725936 (2009) https://doi.org/10.1117/12.812222
Event: SPIE Medical Imaging, 2009, Lake Buena Vista (Orlando Area), Florida, United States
Abstract
The goal of radiotherapy is to deliver maximal dose to the tumor and minimal dose to the surrounding tissue. This requires accurate target definition. In sites were the tumor is difficult to see on the CT images, such as for rectal cancer, PET-CT imaging can be used to better define the target. If the information from multiple PETCT images with different tracers needs to be combined, a nonrigid registration is indispensable to compensate for rectal tissue deformations. Such registration is complicated by the presence of different volumes of bowel gas in the images to be registered. In this paper, we evaluate the performance of different nonrigid registration approaches by looking at the overlap of manually delineated rectum contours after registration. Using a B-spline transformation model, the results for two similarity measures, sum of squared differences and mutual information, either calculated over the entire image or on a region of interest are compared. Finally, we also assess the effect of the registration direction. We show that the combination of MI with a region of interest is best able to cope with residual rectal contrast and differences in bowel filling. We also show that for optimal performance the registration direction should be chosen depending on the difference in bowel filling in the images to be registered.
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Pieter Slagmolen, Pieter Slagmolen, Sarah Roels, Sarah Roels, Dirk Loeckx, Dirk Loeckx, Karin Haustermans, Karin Haustermans, Frederik Maes, Frederik Maes, "Validation of nonrigid registration for multi-tracer PET-CT treatment planning in rectal cancer radiotherapy", Proc. SPIE 7259, Medical Imaging 2009: Image Processing, 725936 (27 March 2009); doi: 10.1117/12.812222; https://doi.org/10.1117/12.812222
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