Recent technical developments and improvements in processing algorithms allow for 3D imaging during interventions and surgeries by using cone-beam CT (CBCT). There are obvious benefits for patients in using CBCT systems, e.g., avoiding stressful patient transports to conventional multi-slice CT scanners (MSCT) for control after interventional and operative procedures. However, there are debates among manufacturers, physicians and the public on the radiation dose applied to patients undergoing CBCT examinations. The aim of this study was to compare a CBCT (Dyna-CT, Siemens) with a MSCT scanner...

A CBCT system recently installed in the operating room of a German urological clinic was used for this study. Four different protocols were used for different putative urological problems: a low-dose protocol, a standard protocol for high-contrast objects, a standard protocol for soft-contrast objects, and a high-dose protocol. The protocols differ in the total number of projections, the dose per projection, and the angulation step width. In contrast to the 360°-rotation of MSCT, the X-ray tube and detector of the CBCT rotate around the isocenter...

On average, the same local skin doses of 10.6mGy were measured in the axial plane of the central ray for the high-contrast protocol of CBCT and MSCT (130kV; 110mAsreference, 16x0.6mm, CTDIvol=7.79mGy). However, there were local dose maxima in case of CBCT exceeding the average dose by ~30% (s. Fig. 2) Effective doses were determined from organ doses considering ICRP Publication 60 [1]. For the different acquisition protocols used in this study, effective doses ranged from 0.52mSv to 5.2mSv for the MSCT and from 0.35mSv to...

Considering dose and image quality, CBCT is well suited for visualizing hard contrast objects. For visualizing soft and medium-hard contrast objects, however, MSCT scanners should be preferred.

[1] ICRP, 1991, "1990 Recommendations of the International Commission on Radiological Protection", ICRP Publication 60, Ann. ICRP 21 (1-3)