Photon-Counting CT Enables Higher Image Quality at a Lower Radiation Dose Compared with a 256-Slice Energy-Integrating Detector CT in Pediatric Patients with Congenital Heart Disease

Background/Objectives: There is an increasing need for cross-sectional imaging in pediatric patients with congenital heart disease. This patient group is highly sensitive to ionizing radiation. The purpose of this article was to evaluate differences in radiation dose and image quality between a first-generation photon-counting (PC)-CT system and a 256-slice single-source energy-integrating detector (EID)-CT in these patients. Methods: We retrospectively assessed effective dose, CT dose index-volume (CTDI_vol), dose length product (DLP), and image quality of all prospectively electrocardiography-gated CTs of the thorax in all patients < 18 years of age examined between February 2021 and August 2024 (n = 43). Two independent observers subjectively scored image quality, vascular contrast, and noise on a 5-point Likert scale. In addition, we assessed the signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) quantitatively. Results: All dose parameters were significantly lower in the PC-CT (n = 27) versus the EID-CT (n = 16) group (mean effective dose: 0.8 ± 0.64 versus 2.2 ± 0.88 mSv, p < 0.001; mean CTDI_vol: 1.22 ± 0.96 versus 4.8 ± 1.08 mGy, p < 0.001; mean DLP: 30.7 ± 31.9 versus 73.7 ± 50.7 mGy*cm, p < 0.001). Overall subjective image quality and contrast were rated higher in the PC-CT group (p = 0.046 and < 0.001, respectively). Quantitative CNR was significantly higher in the PC-CT group (mean 39.1 ± 12.9 versus 26.2 ± 10.8, p = 0.002). Conclusions: PC-CT enables high-quality examinations for the evaluation of congenital heart disease with a highly significant dose reduction compared with a 256-slice single-source EID-CT.