Radiation Dose and Image Quality of Photon-Counting Detector CT for Multiphasic Pre-Transplant Abdominal Imaging in Young Children Aged ≤36 Months: A Propensity-Matched Study.

OBJECTIVES: To compare radiation dose and image quality between photon-counting detector CT (PCD-CT) and dual-layer energy-integrating detector CT (EID-CT) in multiphasic pre-transplant abdominal imaging of young children aged ≤36 months, and to evaluate the phase-dependent performance of 50- and 70 keV monoenergetic reconstructions. METHODS: In this single-centre study, prospective PCD-CT examinations were compared with retrospective EID-CT examinations. After propensity score matching for age, body mass index, and water-equivalent diameter, 54 matched pairs were analysed. Radiation dose, objective image quality, and blinded subjective image quality were assessed across arterial, portal venous, and delayed phases. RESULTS: PCD-CT achieved substantially lower radiation exposure than EID-CT, with reductions of approximately 70-75% in CTDIvol, DLP, and SSDE (all P < 0.001). The 50-keV reconstruction consistently produced the highest attenuation values, whereas 70-keV images showed the lowest noise and the most stable SNR across phases. Differences in CNR were limited and region dependent. Subjective image quality remained diagnostically acceptable for all protocols, with PCD-CT demonstrating comparable or superior score distributions relative to EID-CT, particularly in the portal venous phase. CONCLUSION: In young children aged ≤36 months undergoing multiphasic pre-transplant abdominal imaging, the implemented PCD-CT protocol substantially reduced cumulative radiation dose while maintaining diagnostic image quality compared with the vendor-recommended paediatric dual-layer EID-CT protocol. The complementary performance of 50- and 70-keV reconstructions supports phase-adapted VMI use in this specific paediatric imaging setting. ADVANCES IN KNOWLEDGE: Although radiation-dose reduction with PCD-CT has been reported in other settings, clinical evidence in young children aged ≤36 months undergoing multiphasic pre-transplant abdominal imaging remains limited. This propensity-matched study demonstrates substantial cumulative radiation-dose reduction with preserved diagnostic image quality in this specific paediatric setting and shows complementary phase-dependent performance of 50- and 70-keV VMI reconstructions.