X-ray cone-beam (CB) imaging is moving towards playing a large role in diagnostic radiology. Recently, an innovative, versatile X-ray system (Multitom Rax, Siemens Healthcare, GmbH, Forchheim, Germany) was introduced for diagnostic radiology. This system enables taking X-ray radiographs with high flexibility in patient positioning, as well as acquiring semi-circular short CB scans in a variety of orientations. We show here that this system can be further programmed to accurately scan the entire spine in the weight-bearing position. Such a diagnostic imaging capability has never been demonstrated so far. However, we may expect it to play an important clinical role as clinicians agree that spine diseases would be more accurately interpretable in the weight-bearing position. We implemented a geometry that provides complete data so that CB artifacts may be avoided. This geometry consists of two circular arcs connected by a line segment. We assessed immediate and short-term motion reproducibility, as well as ability to image the entire spine within a Rando phantom. Strongly encouraging results were obtained. Reproducibility with sub-mm accuracy was observed and the entire spine was accurately reconstructed.
Scatter is an important source of image artifacts in cone beam computed tomography. In this study, we investigate the complexity of the scatter signal using Monte Carlo simulations with the anthropomorphic MIRD phantom. We assess the differences in scatter intensities for two angular positions of the source at a given bed position. We identified the contribution of single-scatter (coherent and in-coherent) to total-scatter signal as well as the relative contribution multiple scatter events, and we also identified the scatter-to-primary ratio (SPR). Simulations were performed at different monochromatic beam energies ranging from 40 keV to 120 keV.