Balancing radiation dose and image quality in infants on photon-counting CT for pediatric cardiac imaging: comparing 70 kV and 120 kV protocols.

BACKGROUND

Photon-counting CT (PCCT) has the potential to improve diagnosis and reduce radiation exposure in pediatric congenital heart disease. Early data in pediatric patients has shown advantages of advanced post-processing techniques that are currently only available with high kilovolt (kV) protocols.

OBJECTIVE

The purpose of our study was to compare image quality and radiation dose for low kV (70) and high kV (120) protocols in patients weighing under 10 kg.

METHODS

In this IRB-approved retrospective review of ultra-high pitch cardiac CT scans in patients under 10 kg, we evaluated two protocols on a PCCT scanner: low kV (70) and high kV (120). Patient demographics, contrast-to-noise ratio in aorta and pulmonary artery, and subjective image quality scores using a 5-point Likert scale were evaluated by two readers in addition to radiation dose comparison.

RESULTS

Fifty-eight scans were included, 28 in the 70 kV cohort and 30 in the 120 kV cohort. Median age was 0.17 years for 70 kV and 0.33 years for 120 kV and weight was 4.5 kg for 70 kV and 5.4 kg for 120 kV. Contrast-to-noise ratios (aorta 14.8 vs 17.8, P=0.6) and Likert scores for aorta (median 5 for both groups, P=0.2) were similar for both protocols. Radiation dose was significantly lower in the 70 kV group with CTDI of 0.13 mGy vs 0.25 mGy for 120 kV (P<0.001).

CONCLUSION

A 70 kV protocol shows promise for reducing radiation dose in infants with similar image quality compared to the 120 kV protocol, although advanced spectral reconstructions would not be available.