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Brief description/objective

Objective
The purpose of this study is to assess the ability of a new commercial metal artifacts reduction algorithm (MARIS) for a Siemens CT in restoring the CT image quality, and to evaluate the impact of the corrected tissue density information on the absorbed dose in RT planning (Eclipse, AAA).
Materials and Methods
CIRS phantom has been used for the evaluation of the strength of the CT metal artifacts and also for the evaluation of the dose distribution in RT plans when CT images containing metal implants were used. For the estimation of the impact of metal presence in CT images some of the original CIRS plugs were replaced with steel. Steel inserts were of three different diameters: 1cm, 1.8cm, and 2.5cm. The CT
number of all phantom plugs and also some defined ROIs were compared for the uncorrected CT and the 5 implemented MARIS kernels. Dose distribution accuracy has been evaluated both for phantom and clinical treatment plans, such as hip implants and dental fillings cases.
Results
The composition and geometry of the metallic implants have a major impact on the severity of metal artifacts. The choice for the MARIS kernel giving the best image quality is related to the atomic number of the metallic implant.
Conclusions
Despite evident improvements in recovering missing information in the CT images, MARIS does not account for major influence in dose computation for the investigated anatomical regions. Implementation of 16-bit MARIS-CT corrected images for treatment planning purposes, could provide a more accurate dosimetric approach coupled with a better suppression of CT artifacts.