Novel method for calculating the effective dose using size-specific dose estimates conversion factors in...

Area of Science:

• Medical Physics
• Radiological Sciences
• Radiation Dosimetry

Background:

• Accurate effective dose calculation in computed tomography (CT) is crucial for radiation protection.
• Existing methods may not fully account for individual patient variations in attenuation and size.
• Personalized dosimetry is needed to optimize radiation exposure in diagnostic imaging.

Purpose of the Study:

• To propose and validate a novel method for calculating effective dose in abdomen-pelvis CT.
• To assess the accuracy of the proposed method by comparing it with a simulation-based dose calculator.
• To evaluate the method's sensitivity to individual patient size and body type.

Main Methods:

• A novel method using two conversion coefficients was developed to calculate effective dose.
• The dose-length product was multiplied by effective dose conversion coefficient and size-specific dose estimate conversion factor.
• Effective dose was calculated for 180 adult patients undergoing abdomen-pelvis CT and compared with WAZA-ARI simulation results.

Main Results:

• For male patients, median effective doses showed no significant disparity between methods (relative differences -5% to 6%).
• For female patients, the proposed method yielded slightly lower median effective doses compared to WAZA-ARI (-16% to -9%).
• Relative differences in median effective dose across BMI categories ranged from -18% to -7% for females.

Conclusions:

• The proposed method provides a size-specific effective dose, reflecting individual patient attenuation.
• Differences in results are attributed to the use of different reference phantoms in dose calculations.
• The novel method offers a more personalized approach to effective dose estimation in CT scans.