Coronary Artery Calcium Scoring (CACS) is used for cardiac risk assessment caused by atherosclerotic plaque or other coronary artery diseases. Images from Non-Contrast (NC) cardiac Computed Tomography (CT) scans acquired at 120kVp are used in computing Agatston scoring for CACS. These scans, if done at lower peak voltage can reduce X-Ray radiation exposure. This, however, changes CT attenuation values for all tissues, as well as calcification compared to 120kVp scan, thus making it unusable for Agatston scoring. We propose a learning-based method to translate a CT image acquired at lower kVp to a 120kVp equivalent image, such that the same calcium scoring protocol can be used on these scans. We establish that the proposed method enables appropriate translation of CT values in calcification regions, thereby allowing similar calcium score (error < 6%) for a patient at reduced dose. Our proposed learning-based approach shows robust performance across datasets.
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