Clinical outcomes of sub-millisievert CT evaluation of congenital chest wall deformity using photon counting CT: a new standard of care?

Background Pectus excavatum is the most common congenital chest wall deformity and is typically treated surgically. Disease severity is commonly assessed using the CT-derived Haller Index (HI), creating opportunities to reduce radiation exposure in pediatric patients. Photon-counting detector CT (PCD-CT) enables substantial dose reduction; however, the clinical impact of sub-millisievert (sub-mSv) imaging has not been well established. Objective To evaluate the impact of sub-millisievert (sub-mSv) PCD-CT scans on clinical outcomes in the preoperative assessment of congenital pectus deformities. Methods This retrospective study included patients with congenital pectus deformities treated at a single institution. Introduction of a PCD-CT system and dose-optimized protocols enabled comparison between standard-dose (SD) and sub-mSv CT cohorts. Demographic and clinical characteristics, including age, body mass index (BMI), HI, and effective diameter, were compared, along with radiation exposure metrics and postoperative clinical outcomes. Results There were no significant differences between the SD and sub-mSv cohort in age (unadjusted/adjusted p = 0.32/1), HI (unadjusted p = 0.27/1), BMI (unadjusted p = 0.44/1), or effective diameter (unadjusted p = 0.22/1). Median sub-mSv protocol CTDI _vol , DLP, SSDE, and effective dose were 0.03 mGy, 1.35 mGy*cm, 0.04 mGy, and 0.06 mSv, respectively. Radiation dose was significantly lower than the SD group (Hodges-Lehmann estimate (95% C.I.): effective dose − 2.10 (-2.88, -1.28), SSDE − 6.66 (-8.55, -4.08); unadjusted and adjusted p < 0.001 for both). Postoperative complication rates were low and did not significantly differ between cohorts in the immediate post-operative period or at outpatient follow up (unadjusted and adjusted p = 1 for both). Conclusion Sub-mSv PCD-CT provides diagnostic image quality for preoperative evaluation of congenital chest wall deformities while reducing radiation exposure to levels comparable to a chest radiograph. These findings support broader adoption of low-dose PCD-CT in pediatric chest imaging and emphasize the importance of outcome-based validation of dose reduction strategies.