Fast Monte Carlo Simulation for Patient-specific CT/CBCT Imaging Dose Calculation

TL;DR

This paper introduces gCTD, a GPU-accelerated Monte Carlo simulation tool that significantly speeds up patient-specific CT/CBCT imaging dose calculations while maintaining high accuracy, enabling rapid dose assessment in clinical settings.

Contribution

Development of gCTD, a GPU-based Monte Carlo dose calculation package that achieves over 400x speed-up with high accuracy for patient-specific imaging dose estimation.

Findings

gCTD attains ~400x speed-up over EGSnrc in water phantom

gCTD achieves ~76.6x speed-up in Zubal phantom

Dose calculation for Zubal phantom takes ~17 seconds with 0.4% std deviation

Abstract

Recently, X-ray imaging dose from computed tomography (CT) or cone beam CT (CBCT) scans has become a serious concern. Patient-specific imaging dose calculation has been proposed for the purpose of dose management. While Monte Carlo (MC) dose calculation can be quite accurate for this purpose, it suffers from low computational efficiency. In response to this problem, we have successfully developed a MC dose calculation package, gCTD, on GPU architecture under the NVIDIA CUDA platform for fast and accurate estimation of the x-ray imaging dose received by a patient during a CT or CBCT scan. Techniques have been developed particularly for the GPU architecture to achieve high computational efficiency. Dose calculations using CBCT scanning geometry in a homogeneous water phantom and a heterogeneous Zubal head phantom have shown good agreement between gCTD and EGSnrc, indicating the accuracy of our code. In terms of improved efficiency, it is found that gCTD attains a speed-up of ~400 times in the homogeneous water phantom and ~76.6 times in the Zubal phantom compared to EGSnrc. As for absolute computation time, imaging dose calculation for the Zubal phantom can be accomplished in ~17 sec with the average relative standard deviation of 0.4%. Though our gCTD code has been developed and tested in the context of CBCT scans, with simple modification of geometry it can be used for assessing imaging dose in CT scans as well.