[Evaluation of calibration error for applying exposure index]

Area of Science:

• Medical Physics
• Radiologic Technology

Context:

• Digital radiography systems utilize manufacturer-specific exposure indicators (EI).
• The International Electrotechnical Commission (IEC) introduced a unified EI concept to standardize exposure assessment.
• Existing IEC calibration conditions have limitations regarding beam quality variations.

Purpose:

• To evaluate the calibration accuracy of the IEC's exposure index (EI) under varying geometric conditions and added filtrations.
• To determine the relative errors in EI calibration concerning field size and source-image receptor distance (SID).

Summary:

• Relative calibration errors were calculated for EI values (200, 500, 1000) across different field sizes (10x10 to 43x43 cm) and SIDs (100 to 200 cm).
• Beam qualities were adjusted using specific added filtrations (0.5 mm Cu+2 mm Al, 0.6 mm Cu, 21 mm Al) to RQA 5 standards.
• Air kerma at the detector surface ranged from 0.18 to 26.3 µGy, reflecting clinical use.

Impact:

• The study demonstrates that EI calibration errors are minimal (<6%) for field sizes >10x10 cm and SID >100 cm.
• Findings support the reliability of the IEC's EI concept for consistent exposure monitoring in digital radiography.
• This research aids in optimizing image quality and radiation dose management in diagnostic imaging.