CT: Technology and PhysicsAn Analytic Method for Calculating Scanner-, Kilovoltage Peak–, and Patient Size–Specific Hounsfield Unit Scale Thresholds for Agatston ScorePeng, Boyu MS∗; Jambawalikar, Sachin PhD∗; Einstein, Andrew J. MD, PhD∗,† Author Information From the Departments of ∗Radiology †Medicine, Seymour, Paul, and Gloria Milstein Division of Cardiology, Columbia University Irving Medical Center and NewYork-Presbyterian Hospital, New York, NY. Received for publication June 18, 2021; accepted December 20, 2021. Correspondence to: Andrew J. Einstein, MD, PhD, Department of Medicine, Seymour, Paul, and Gloria Milstein Division of Cardiology, Columbia University Irving Medical Center and NewYork-Presbyterian Hospital, 622 West 168th St, PH 10-203E, New York, NY 10032 (e-mail: [email protected]). The authors declare no conflict of interest. Journal of Computer Assisted Tomography: 5/6 2022 - Volume 46 - Issue 3 - p 423-433 doi: 10.1097/RCT.0000000000001293 Buy Metrics Abstract Objective This study aimed to calculate scanner-, kilovoltage peak (kVp)–, and patient size–specific computed tomography (CT) number thresholds for determining Agatston score (AgSc). Methods The proposed method was validated using calcium measurements in an anthropomorphic phantom for 4 CT scanners made by 4 vendors. The derived mass concentration (γ) thresholds were used to calculate kVp- and patient size–specific CT number thresholds. Two models were applied to reduce intrascanner and interscanner AgSc variation, respectively. Results The mean error of the modeled CT numbers is 1.8% (0.1%–4.4%). Model 1 has comparable results to the published phantom calibration method for an average-size patient (error, 1.5%; 0.1%–5.1%). The size- and the kVp-dependent fitting of modeled results have R2 greater than 0.965. Conclusions Our results show a potential to enable accurate determination of AgSc under diverse conditions (eg, reduced tube potential) and are more easily applicable to different patient sizes than the phantom calibration method. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.