Evaluating the Effect of Log-linear Interpolation on Half-value Layers Using Monte Carlo Simulation

of air, was positioned 100 cm from the source. The Al filter thickness for the HVL was varied in increments of 0.1 mm. The HVL was calculated by linear interpolation, and the relative error was determined based on the minimum Al spacing. The X-ray tube voltages used were those of the RQR series (40, 50, 60, 70, 80, 90, 100, 120, and 150 kV). The beam qualities obtained from the measurements and the Monte Carlo simulation system were consistent with those specified for the RQR series in IEC 61267 within ±3.5%. The relative error of HVL for each tube voltage determined by simulation ranged from -0.5 to 4.6%, with a mean±standard deviation (median) of 1.12±0.95% (0.88%). The relative error was larger when the difference between the Al filter combinations was large and the interpolation coefficient α was 0.5. When the filter spacing is less than half the HVL, the accuracy of log-linear interpolation in HVL is less than ±1.5% relative error.