Institutional computed tomography diagnostic reference levels based on water-equivalent diameter and size-specific...

Area of Science:

• Medical Physics
• Radiology
• Radiation Dosimetry

Background:

• Computed tomography (CT) radiation dose varies significantly with patient size.
• Traditional diagnostic reference levels (DRLs) do not account for patient size, potentially leading to inaccurate assessments.
• Size-specific dose estimates (SSDEs) offer a more personalized approach to radiation dosimetry in CT.

Purpose of the Study:

• To generate size-specific institutional DRLs (iDRLs) for chest and abdominopelvic CT examinations.
• To evaluate the correlation between patient size (water-equivalent diameter, Dw) and SSDEs.
• To assess the feasibility and potential benefits of implementing SSDE-based DRLs.

Main Methods:

• A retrospective study of 1690 CT examinations was conducted.
• Size-specific dose estimates (SSDEs) were calculated based on the mean water-equivalent diameter (Dw) of the scan volume.
• Institutional DRLs (iDRLs) were generated as the 75th percentile of SSDEs, stratified by Dw.

Main Results:

• Mean SSDEs were higher than volumetric CT dose index (CTDIvol) across chest, abdominopelvic, and upper abdominal CT scans.
• Strong linear correlations were observed between Dw and SSDEs for all examined CT protocols (R² values ranging from 0.66 to 0.98).
• Size-specific, Dw-dependent iDRLs were successfully generated, enabling more precise radiation exposure analysis.

Conclusions:

• Size-specific institutional DRLs based on SSDEs and Dw are feasible and provide a more comprehensive analysis of CT radiation exposure.
• The implementation of SSDEs into national DRLs could enhance radiation safety protocols.
• Personalized dosimetry through size-specific DRLs is crucial for optimizing radiation dose in CT imaging.