Optimizing Radiation Dose and Image Quality in Stroke CT Protocols: Proposed Diagnostic Reference Levels for...

Area of Science:

• Radiology
• Medical Imaging
• Neurology

Background:

• Acute ischemic stroke protocols often include non-contrast CT (NCCT), CT angiography (CTA), and CT perfusion (CTP).
• Expanding protocols with multiphase CTA (MP-CTA) may enhance diagnostic confidence but requires dosimetry evaluation.
• Diagnostic reference levels (DRLs) are not established for MP-CTA or CTP.

Purpose of the Study:

• To present dosimetry data and image quality for MP-CTA and CTP in a large patient cohort.
• To establish DRLs for extended stroke imaging protocols.
• To compare radiation dose and image quality across different CT scanner types.

Main Methods:

• Retrospective analysis of 1790 patients undergoing extended stroke protocols on dual-source (DSCT) and single-source (SSCT) scanners.
• Evaluation of radiation dose (CTDIvol, DLP, effective dose) and image quality (CNR, subjective rating).
• DRLs defined as the 75th percentile of CTDIvol; statistical analysis using Kruskal-Wallis and Dunn's tests.

Main Results:

• Radiation doses were significantly higher for SSCT compared to DSCT.
• Established DRLs for NCCT, arterial CTA, MP-CTA (early/late venous), and CTP.
• Protocol optimization with DSCT reduced CTP dose by 28.2%.
• Highest CNR for arterial CTA with SSCT; lowest for early venous CTA with DSCT-2.
• Subjective image quality was excellent, with minor noise noted in MP-CTA on DSCT-2.

Conclusions:

• Additive MP-CTA scans result in only a minor increase in radiation exposure, particularly with DSCT.
• CTP utilization should be restricted to selected patients to optimize radiation dose.
• The findings support the integration of MP-CTA into stroke protocols with appropriate scanner selection.