Adaptive Statistical Iterative Reconstruction (ASiR)

ASIR focuses on the statistical modeling of the noise properties of the system in conjunction with the properties of the scanned object. As result , it provides significant benefit for those examinations that may experience limitations due to noise in the reconstructed images. In the case of spectral imaging , this is applied to reduce the nosie in the material density to enhance image quality.

While simultaneously leveraging well known noise correlation properties of the projection space material decomposition process. (Alvarez and Seppi, 1979)

Figure 2 shows the result of the unique integration of these two approaches . the Leftmost image displayed for reference is that of a monochromatic 75 keV, the central image is that of its corresponding iodine density and the right most image shows the corresponding water density

GE Healthcare jumped ahead of competitors in the race to cut patient dose with the commercial release in 2008 of its Adaptive Statistical Iterative Reconstruction (ASIR), the first software to clean up CT images and, in the process, allow dramatic reductions—up to 50%—in patient radiation dose. In the first day of this year’s ISCT symposium, iterative reconstruction was hailed repeatedly as the leading solution to the hottest issue in CT patient safety.
Yet providers have been slow to adopt this technology. Only about 330 CTs are currently running ASIR, despite being standard on GE’s flagship, the Discovery CT750 HD, since the end of 2008, commercially available on the VCT since mid-2009, and available outside the U.S on the BrightSpeed 16 for a year. ASIR is also available as a field upgrade for certain high-performance systems.