Shuai Leng PhD, Presenter: Nothing to Disclose

Lifeng Yu PhD, Abstract Co-Author: Nothing to Disclose

Christian Eusemann PhD, Abstract Co-Author: Employee, Siemens AG

Bernhard Schmidt PhD, Abstract Co-Author: Employee, Siemens AG

Thomas G. Flohr PhD, Abstract Co-Author: Employee, Siemens AG, Forchheim, Germany

Cynthia H. McCollough PhD, Abstract Co-Author: Research grant, Siemens AG

The purpose of this study was to compare the image quality obtained using dual-source CT (Definition Flash, Siemens Healthcare) at a pitch value of 3.2 to that obtained using single-source CT at a pitch value of 1.0.

With the use of two x-ray sources and two data acquisition systems, spiral pitch values up to 3.2 are achievable provided that the desired field of view is fully scanned by the smaller of the two detectors. Spatial and low-contrast resolution, image uniformity and noise, and CT number accuracy and linearity were assessed using the ACR CT accreditation phantom for single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2. Slice sensitivity profiles were measured for different nominal slice thicknesses and an anthropomorphic phantom was scanned to assess image artifacts. Radiation output, as quantified using CTDIvol, was identical for all scans as a consequence of prescribing the same effective mAs (mAs/pitch) for each protocol. Image noise as a function of the spiral pitch was additionally assessed for the dual-source scan mode using a 30cm diameter cylindrical water phantom scanning at pitch values from 1.6 to 3 in steps of 0.2.

No differences in quantitative measures of image quality were found between single-source scans at pitch=1.0 and dual-source scans at pitch = 3.2 for spatial and low-contrast resolution, CT number accuracy and linearity, slice sensitivity profile, image uniformity, and noise. The noise values were essentially constant, although a slight decrease towards smaller pitch was noted. However, while not severe, artifacts at structures with rapidly varying attenuation along the z-axis were found to be more prevalent for the dual-source pitch = 3.2 scan mode, particularly for head scans.

In summary, a dual-source CT, high pitch value (up to 3.2) scan mode with 75 ms nominal temporal resolution produced equivalent image quality relative to single-source, nominal 280 ms temporal resolution scans using a more typical pitch value (pitch = 1.0).

The reduction in overall scan time and improved temporal resolution of high pitch, dual source CT may offer significant advantages for cardiovascular, thoracic, trauma, and pediatric CT applications.

Leng, S, Yu, L, Eusemann, C, Schmidt, B, Flohr, T, McCollough, C, Dual-Source Spiral CT at Pitch Values up to 3.2: Assessment of Image Quality.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8004715.html