Patient Dimensions From a Single CT Image Provide a Clinically Practical and Accurate Method for Dose Estimation in...

Area of Science:

• Medical Physics
• Veterinary Radiology
• Radiological Dosimetry

Background:

• Size-specific dose estimate (SSDE) refines dose assessment in CT imaging.
• AAPM metrics offer a method for estimating dose based on patient size.
• Canine CT dose evaluation requires size-specific considerations.

Purpose of the Study:

• To assess the correlation between AAPM geometric size metrics and water-equivalent diameter (D_w) in canine abdominal CT.
• To compare institutional SSDE values in dogs with human benchmarks.
• To evaluate the feasibility of applying SSDE methodology to veterinary CT.

Main Methods:

• Retrospective analysis of 30 canine abdominal CT scans across weight categories.
• Linear regression to analyze relationships between geometric metrics (DV, LAT, etc.) and D_w.
• Comparison of calculated SSDEs with human dose reference levels.

Main Results:

• Combined dorsoventral (DV) and lateral (LAT) dimensions showed the strongest correlation with D_w (R² = 0.94).
• Scanner-reported CTDI_vol underestimated SSDE by 50%.
• The 75th percentile SSDE for canine abdominal CT was 21 mGy, significantly higher than human reference levels.

Conclusions:

• AAPM geometric metrics are feasible for canine abdominal CT SSDE estimation.
• Canine abdominal CT doses may be higher than human benchmarks, indicating potential for dose optimization.
• Incorporating patient size into CT dose estimation is crucial for accurate assessment in veterinary medicine.