Author: Niki Fitousi, Anna Romanyukha, Stuart Utting 👨🔬
Affiliation: University Hospitals Dorset, Qaelum NV 🌍
Purpose:
For increased patient safety and with a focus on sustainability in the radiology department, efforts are being made to optimize contrast media usage. In this study, the possibility of utilizing post-localizer metrics provided by the CT scanner to automatically determine the required contrast dose for common exams was investigated.
Methods:
One year of data for two standard weight-based contrast CT protocols was extracted from the dose management system: portal abdomen pelvis (protocol 1) and arterial chest portal abdomen pelvis (protocol 2). Standard protocol composition was determined, and scans were grouped by scan settings including kVp, collimation, exposure time per rotation and pitch.
Correlation between administered contrast volume and scan CTDIvol was assessed per group and protocol using Pearson’s correlation coefficients. Recorded patient weight was not available for the exams. As the department practice is to determine contrast dosage using 10 kg weight bands an assumption is that weight was measured/estimated prior to contrast administration.
Results:
Protocol 1 consisted of 1 localizer, 1 bolus tracking, 1 spiral scan, 75% (n=505) of the spiral scans were performed using standard settings of kVp=120, pitch=0.81, collimation=40 mm, and exposure time per rotation=0.5 s.
Protocol 2 consisted of 1 localizer, 1 bolus tracking and 2 spiral scans. 94% (n=553) and 98% (n=506) of spiral scans 1 and 2, respectively, used standard settings of kVp=100, pitch=0.81, collimation=40 mm, and exposure times per rotation=0.35 s and 0.5 s, respectively.
Scan CTDIvol and administered contrast volume showed good correlation, with R=0.98 for protocol 1 and R=0.99 for both spiral scans in protocol 2.
Conclusion:
Post-localizer dose metrics that account for patient size may be a reliable way to predict the required contrast volume, benefiting the department by optimizing contrast administrations, reducing costs and limiting patient contrast intake.