Size-Specific Optimization of Interventional CT Protocols with Clinical Performance Assessment
Abstract
Purpose
Interventional CT procedures often involve multiple scans of the same anatomy, contributing substantially to patient dose. Because guidance tasks do not require diagnostic‑quality imaging, helical protocol parameters can be reduced to lower exposure, which is especially critical in pediatric cases. This study demonstrates the feasibility of size‑specific optimization of dose and image quality for CT‑guided interventions using patient data, phantom measurements, and physician feedback.
Methods
Dose metrics were evaluated to understand the effect of scan mode selection (i.e., helical or axial CT fluoroscopy) and protocol techniques (e.g., tube potential and current) on patient dose. The Mercury 4.0 Phantom (Sun Nuclear) was used to explore the impact of dose reduction strategies (e.g., automatic tube-current modulation (ATCM) and iterative reconstruction) on image quality across a range of patient sizes. A survey was created to collect details from technologists and physicians on the performance of optimized protocols.
Results
Size-specific helical procedure protocol bins were designed to be efficiently integrated into the procedure workflow. For smaller patient diameters, phantom data indicated fixed tube currents with lower tube potentials can provide approximately 25% dose reduction from diagnostic protocols, and the associated changes in noise (15% increase) and detectability (10% decrease) remain within acceptable ranges. For relatively larger patient diameters, ATCM paired with higher tube potential provides approximately 35% dose reduction with 10-15% changes in noise and detectability. Since the clinical implementation of the updated protocols, default parameters have been rarely adjusted during procedures, and substantial dose reduction has been achieved with excellent image quality ratings.
Conclusion
It is essential that interventional protocols have reduced dose compared to diagnostic protocols. Optimization of dose and image quality for helical CT procedure protocols should be size-dependent to provide additional dose reduction for pediatric patients. Integration of physician feedback can ensure clinical performance of protocols is successful.