Patient positioning during pediatric cardiothoracic computed tomography using a high-resilience pad system and pre-scan measurement of chest thickness.

ABSTRACT

Patient positioning at the isocenter of the CT gantry is important for optimizing image quality and radiation dose, but accurate positioning is challenging in pediatric patients. We evaluated whether the high-resilience pad and pre-scan measurement of chest thickness allow accurate positioning in pediatric patients with congenital heart disease. Sixty-seven patients aged 7 years or younger who underwent cardiothoracic CT were enrolled. The ideal table height, defined as the position at which the scanner's and patient's isocenters coincided, was determined by radiographers either manually (manual group) or based on the pad's and chest's thickness (calculated group). The distance between the two isocenters and image quality were evaluated. The calculated group demonstrated smaller isocenter distance and standard deviation (distance 0.2 ± 5.8 mm vs. - 8.3 ± 11.6 mm, p < 0.01; absolute value 4.1 [1.9-8.0] mm vs. 12.3 [5.1-16.3] mm, p < 0.01), and higher signal-to-noise ratio (SNR) and dose-normalized SNR (SNRD) in the descending aorta than the manual group (SNR 39.8 [31.0-53.7] vs. 31.9 [28.9-36.6], p = 0.048, SNRD 39.8 [31.0-53.7] vs. 31.9 [28.9-36.6], p = 0.04). The system allowed for more accurate positioning in pediatric cardiothoracic CT, yielding higher image quality.