Cuong Tho Nguyen MD, Presenter: Nothing to Disclose

Katrina M. Read MS, Abstract Co-Author: Employee, Koninklijke Philips Electronics NV

Eliot L. Siegel MD, Abstract Co-Author: Research grant, General Electric Company Speakers Bureau, Siemens AG Board of Directors, Carestream Health, Inc Research grant, XYBIX Systems, Inc Research grant, Steelcase, Inc Research grant, Anthro Corp Research grant, RedRick Technologies Inc Research grant, Evolved Technologies Corporation Research grant, Barco nv Research grant, Intel Corporation Research grant, Dell Inc Research grant, Herman Miller, Inc Research grant, Virtual Radiology Research grant, Anatomical Travelogue, Inc Medical Advisory Board, Fovia, Inc Medical Advisory Board, Mercury Computer Systems, Inc Medical Advisory Board, McKesson Corporation Medical Advisory Board, Carestream Health, Inc Medical Advisory Board, Bayer AG Medical Advisory Board, TeraRecon, Inc

Iterative reconstruction has been promoted by various vendors as an effective way to reduce CT radiation dose while maintaining image quality. We are not aware of any previous studies that have quantified or tested the wide variety of claims that have been made for the positive impact of iterative reconstruction nor are we aware of any studies that have compared the effectiveness of iterative reconstruction across multiple vendors. The purpose of our exhibit is to, in a de-identified way, evaluate the effectiveness of various reconstruction approaches on image quality utilizing the ACR phantom as a source of quantitative analysis.

CT scans of an ACR phantom were performed on scanners from three major CT manufacturers at a variety of low dose (mAS and kVp’s ranging from 11 to 50 and 80 to 120, respectively) settings. Image matrix sizes of 512 by 512 and 1024 by 1024 were utilized. The phantom were quantitatively evaluated using associated software for a number of parameters that determined spatial and contrast resolution as well as signal to noise levels. These phantoms were then reconstructed utilizing the kernel of reconstruction recommended by the manufacturer for abdominal CT studies utilizing both filtered back projection as well as the vendor’s iterative reconstruction techniques. The data were entered into a spreadsheet and subsequently into a statistical package for analysis.

The success of iterative reconstruction varied substantially among the three vendors for the low dose CT protocols but did have a positive impact on image “quality.” The positive impact of iterative reconstruction was greatest for the lowest dose studies and for those obtained at higher matrix sizes. The specific differences will be discussed in detail without referring to the identity of the specific vendors.

In addition to subjective evaluation of image “quality” which can be affected by many parameters, it is also important to determine the impact of the newly developed CT iterative reconstruction algorithms in a quantitative manner utilizing phantoms. Our study suggests that the quantitative improvement in noise, spatial and contrast resolution is more modest than would be suggested by the vendors’ claims for potential dose reduction. Additional studies can be performed utilizing simulated dose reduction and cadaver specimens to verify our results in humans.

CT radiation dose reduction.

Nguyen, C, Read, K, Siegel, E, Quantifying the Impact of Iterative Reconstruction for Three Major CT Vendors Utilizing the ACR Phantom.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9006838.html