Implementation of Institutional Size-Specific Diagnostic Reference Levels for CT Angiography

Area of Science:

• Radiology and Imaging
• Medical Physics

Background:

• Computed tomography angiography (CTA) examinations are crucial for diagnosing vascular diseases.
• Establishing appropriate radiation dose levels is essential for patient safety and effective imaging.
• Current national diagnostic reference levels (DRLs) are often size-independent, potentially leading to suboptimal dose assessments for individual patients.

Purpose of the Study:

• To develop institutional size-specific DRLs for CTA examinations of the aorta, pulmonary arteries, and pelvis/lower extremity.
• To evaluate the effectiveness of size-specific DRLs in identifying radiation dose outliers compared to size-independent DRLs.

Main Methods:

• A retrospective analysis of 1344 CTA examinations was conducted.
• Water equivalent diameter (Dw) was calculated for each patient to determine body size.
• The relationship between Dw and computed tomography dose index (CTDIvol) was analyzed to establish institutional DRLs at the 75th percentile.

Main Results:

• A strong linear correlation was observed between Dw and CTDIvol across all CTA protocols (R² > 0.93).
• Institutional DRLs were found to be lower than national size-independent DRLs for average-sized patients.
• Size-specific DRLs identified a significantly higher proportion of dose outliers in small patients (56.4%) compared to size-independent DRLs (16.2%).

Conclusions:

• Institutional size-specific DRLs provide a more precise method for analyzing radiation doses in CTA examinations.
• Implementing size-specific DRLs can enhance radiation dose optimization and patient safety by better identifying individuals receiving excessive radiation exposure.