[Calculation of Ambient Dose in X-ray Fluoroscopy Room Using Monte Carlo Simulation Based on CAD Data]

The "Manual method" of geometry construction often fails to reproduce the intricate shapes of medical device, leading to inaccuracies in scattering phenomena simulations. In contrast, CAD data generated via 3D scanning offers a promising solution for improving the accuracy of ambient dose measurements. This study evaluates the effect of a CAD-based geometry construction method (the CAD method) and compares its performance against the traditional Manual method.

A 3D scanner was employed to capture the structural details of an X-ray fluoroscopy device, which were then converted into CAD data. These data were imported into the Monte Carlo simulation code PHITS to reconstruct the geometry of the X-ray fluoroscopy room. The ambient dose calculated by PHITS were validated against measurements obtained using an ionization chamber survey meter. In addition, the ambient dose calculations from the CAD method were compared with those from the Manual method to identify discrepancies.

The CAD method demonstrated high precision, with an error rate between measured and calculated values within 5.3% across all measurement points, and within 3.3% in the immediate vicinity of the device. A comparison of ambient doses calculated using the CAD-based method and the Manual method revealed that the error rate increased in the vicinity of the device.

The results demonstrate that the CAD method is superior for detailed ambient dose calculations, particularly in vicinity of the device where geometric complexity is high. This approach is highly effective when high-precision dose distribution is required in clinical environments.