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Thank you ladies
You gave useful information. Errors has been noticed between the named structures, indexed breast board was used and ROI covering the breast for the setup was preferred, (kV/kV match was done as the compromise between the sternum and ribs). However, at the beginning of this year AlignRT CBCT- study was published and there was concluded that pitch- and longitudinal problems in the patient position occurs also with the suggested ROI which covers the breast (Radiotherapy setup displacement in breast patients: 3D surface imaging experience, 2018). So if we keep the focus on FB setup now, it seems that based on published (n=10) and unpublished (n=50) results both deformed breast and rigid part of the chest wall surface can be shifted in SI direction in contrast to vertebra without AlignRT RTDs seeing it. This kind of problem is daily visible in kV- images with laser setup and not much can be done for it. With SGRT there was supposed to be a potential to notice and decrease this kind of error and it is in our interest to solve this as effectively as possible. The solution is not so simple that the kV-image was acquired at certain breathing phase, because systematic error is found between vertebra and sternum in SI direction. So join the discussion as a goal to decrease this typical error in the field of RT with SGRT!
Best regards Marko