ACCURATE KAP METER CALIBRATION AS A PREREQUISITE FOR OPTIMISATION IN PROJECTION RADIOGRAPHY

Area of Science:

• Medical Physics
• Radiological Imaging
• Radiation Dosimetry

Background:

• Modern X-ray units use KAP meters to measure air kerma-area product (PKA).
• Some KAP meters exhibit significant energy-dependent bias (up to 25% uncertainty), hindering accurate dose optimization.
• International standards (IEC) allow substantial uncertainty, while IAEA recommends <7%.

Purpose of the Study:

• To present and validate methods for correcting energy-dependent bias in built-in KAP meters.
• To achieve an uncertainty of less than 7% for PKA measurements, as recommended by IAEA.
• To ensure accurate PKA calibration for effective dose optimization in projection radiography.

Main Methods:

• Utilized a reference KAP meter calibrated at a standards laboratory.
• Developed a computational model for calculating beam quality correction factors.
• Employed an energy-independent dosemeter for direct measurement of beam quality corrections.

Main Results:

• Observed biases up to 35% in built-in KAP meter readings.
• Demonstrated that energy-dependent calibration factors are necessary for unbiased PKA measurements.
• Achieved measurement uncertainties below 7% using the described calibration methods.

Conclusions:

• Accurate KAP meter calibration is essential for dose optimization in projection radiography.
• The presented methods effectively correct for KAP meter bias, leading to improved measurement accuracy.
• Implementing these calibration strategies ensures reliable PKA data for patient safety and effective radiation use.