In most clinical image-guided procedures like stenting and needle based biopsies one is only interested to visualize a specific part of the patient’s body. Therefore, only the relevant parts should be irradiated in order to minimise the patient’s dosage. Utilizing such volume-of-interest imaging has the potential to save a lot of dose but causes artifacts to appear in the resulting image, stemming from the reconstruction from incomplete projections. Modern bi-plane C-arm CT systems have the potential to acquire some projections complete and other projections limited to the region of interest. Here, we investigate how extrapolation methods can be used to replace the missing data and minimize the resulting artifacts. A new extrapolation method is proposed and compared to an existing extrapolation method. Subsequently, both the image quality in the recorded region of interest as well as the extrapolated outer area are examined. It is shown, that blockwise contiguous truncated/non-truncated bi-plane projections are an advantageous compromise between fully acquired data and completely truncated data. Significant amounts of dosage can be saved, whilst largely maintaining the relevant image quality.
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