On the potential of ROI imaging in x-ray CT - A comparison of novel dynamic beam attenuators with current technology.

Purpose: In this work, we explore the potential of region-of-interest (ROI) imaging in x-ray computed tomography (CT). Using two dynamic beam attenuator (DBA) concepts for fluence field modulation (FFM) previously developed, we investigate and evaluate the potential dose savings in comparison with current FFM technology.

Methods: ROI imaging is a special application of FFM where the bulk of x-ray radiation is propagated toward a certain anatomical target (ROI), specified by the imaging task, while the surrounding tissue is spared from radiation.

The z-sbDBA, a new concept for a dynamic sheet-based fluence field modulator in x-ray CT.

Purpose: We present a new concept for dynamic fluence field modulation (FFM) in x-ray computed tomography (CT). The so-called z-aligned sheet-based dynamic beam attenuator (z-sbDBA) is developed to dynamically compensate variations in patient attenuation across the fan beam and the projection angle. The goal is to enhance image quality and to reduce patient radiation dose.

Technical Note: Sheet-based dynamic beam attenuator - A novel concept for dynamic fluence field modulation in x-ray CT.

Purpose: It has been a long-standing wish in computed tomography (CT) to compensate the emitted x-ray beam intensity for the patient's changing attenuation during the rotation of a CT data acquisition. The patient attenuation changes both spatially, along the fan beam angle, and temporally, between different projections. By modifying the pre-patient x-ray intensity profile according to the attenuation properties of the given object, image noise can be homogenized and dose can be delivered where it is really needed.