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Using Slice Thickness Wire Pattern in ACR 464 CT Phantom to Study Effects of Reconstruction Algorithms On CTA Protocols

G Li1*, Y Liang2, (1) University of Maryland, Baltimore, Baltimore, MD, (2) ,


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library


Various testing methods (e.g., noise power spectrum, modulation transfer function, and hoteling observer studies) have been investigated to study how iterative reconstruction (IR) algorithms affects image quality. However, it is not trivial for physicists in field to implement these methods. This study aims to propose an approach to demonstrate the effects of various IR methods on small objects with relatively high contrast using the slice thickness wire objects in the ACR 464 CT phantom commonly used in field. Using this approach, physicists in field can better understand how various IR settings affect image quality of small vessels and optimize CT angiography protocols accordingly.


Axial images of the ACR 464 CT phantom were acquired using standard head CT protocols on a Siemens Force and a Philips Brilliance iCT CT scanner. The images were reconstructed with various IR algorithms (ADMIRE, iDose and IMR) and strengths. The line profile across all wires for the slice thickness testing were extracted using ImageJ (Fig. 1a). The peak values of the line profiles represented the object signals and valleys the background signals

Figure 1a & 1b showed the peak and valley signals varied and the contrast between the wire and background was reduced on the iCT (IMR) while remained essentially unchanged on the iCT with iDose and the Force with ADMIRE.

The wire pattern for the slice thickness testing can be used to study the effects of various IR settings on small vessels in CT angiogram.


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