Improved Dose Estimates for Fluoroscopically Guided Lumbar Epidural Injections.

Area of Science:

• Medical Physics
• Radiology
• Radiation Dosimetry

Background:

• Fluoroscopy-guided procedures rely on system-reported dosimetry values like air Kinetic Energy Released per unit MAss and dose-area product for radiation burden estimation.
• These metrics do not account for factors such as table attenuation and inherent system dosimetry inaccuracies (±35% required accuracy).

Purpose of the Study:

• To determine the impact of system inaccuracies and table attenuation on fluoroscope-reported dose values.
• To improve the accuracy of radiation dose assessment in fluoroscopy-guided procedures.

Main Methods:

• Collected acquisition and patient exposure data from 46 patients undergoing fluoroscopy-guided lumbar epidural injections.
• Evaluated fluoroscope dosimetry accuracy and table attenuation as a function of kVp to generate correction factors.
• Characterized procedures using gantry angles, x-ray technique factors, and field sizes.

Main Results:

• System-reported dose-area product values overestimated the total patient entrance dose-area product by an average of 34% (range: 13-44%).
• Potential for substantially higher errors exists with less accurate fluoroscopes or anterior-posterior projections.
• Correction of system-reported dosimetry values for inaccuracies and variability significantly improves dose value accuracy.

Conclusions:

• Accurate assessment of patient radiation burden requires corrections for system output inaccuracies and acquisition factors like table attenuation.
• Reliable dose estimation is essential for patient safety in fluoroscopy-guided interventions.