Development of size-specific institutional diagnostic reference levels for computed tomography protocols in neck...

Area of Science:

• Radiology and Imaging
• Medical Physics
• Radiation Safety

Background:

• Diagnostic Reference Levels (DRLs) are crucial for optimizing radiation dose in medical imaging.
• Computed Tomography (CT) protocols for neck imaging vary, necessitating size-specific dose assessments.
• Previous DRLs may not adequately account for patient size variations in neck CT.

Purpose of the Study:

• To develop size-specific institutional DRLs for cervical spine CT, CT angiography (CTA), and staging CT.
• To compare these newly developed institutional DRLs with existing national DRLs.
• To assess the effectiveness of current CT protocols in managing radiation exposure for neck imaging.

Main Methods:

• Retrospective analysis of 1,200+ cervical CT examinations (spine, CTA, staging) from 01/2016 to 06/2017.
• Determination of volumetric CT dose index (CTDIvol) and dose-length product (DLP) for each scan.
• Calculation of size-specific DRLs using linear regression based on patient water-equivalent diameter (dw) and the 75th percentile.

Main Results:

• Size-specific institutional DRLs for CTDIvol ranged from 5-29 mGy and for DLP from 130-640 mGycm across different neck CT protocols and patient sizes.
• A clear linear relationship was observed between increasing patient size (dw) and both CTDIvol and DLP.
• Institutional DRLs were substantially lower than national DRLs, with reductions of up to 81% for CTDIvol and 67% for DLP.

Conclusions:

• Size-specific institutional DRLs for neck CT examinations were successfully generated.
• Mean institutional CTDIvol and DLP values were found to be well below established national DRLs.
• The findings suggest potential for dose reduction or validation of current practices in neck CT imaging.