Monte Carlo simulation of inverse geometry x-ray fluoroscopy using a modified MC-GPU framework

Abstract

Scanning-Beam Digital X-ray (SBDX) is a technology for low-dose fluoroscopy that employs inverse geometry x-ray beam scanning. To assist with rapid modeling of inverse geometry x-ray systems, we have developed a Monte Carlo (MC) simulation tool based on the MC-GPU framework. MC-GPU version 1.3 was modified to implement a 2D array of focal spot positions on a plane, with individually adjustable x-ray outputs, each producing a narrow x-ray beam directed toward a stationary photon-counting detector array. Geometric accuracy and blurring behavior in tomosynthesis reconstructions were evaluated from simulated images of a 3D arrangement of spheres. The artifact spread function from simulation agreed with experiment to within 1.6% (rRMSD). Detected x-ray scatter fraction was simulated for two SBDX detector geometries and compared to experiments. For the current SBDX prototype (10.6 cm wide by 5.3 cm tall detector), x-ray scatter fraction measured 2.8–6.4% (18.6–31.5 cm acrylic, 100 kV), versus 2.1–4.5% in MC simulation. Experimental trends in scatter versus detector size and phantom thickness were observed in simulation. For dose evaluation, an anthropomorphic phantom was imaged using regular and regional adaptive exposure (RAE) scanning. The reduction in kerma-area-product resulting from RAE scanning was 45% in radiochromic film measurements, versus 46% in simulation. The integral kerma calculated from TLD measurement points within the phantom was 57% lower when using RAE, versus 61% lower in simulation. This MC tool may be used to estimate tomographic blur, detected scatter, and dose distributions when developing inverse geometry x-ray systems.

Method for dose-reduced 3D catheter tracking on a scanning-beam digital x-ray system using dynamic electronic collimation

“…The dose reduction associated with a moving elliptical ROI was evaluated using a Monte Carlo simulation package developed for the SBDX geometry. 17 This simulation package has been previously validated against relative DAP measurements performed in regional adaptive exposure (RAE) versus full-FOV scanning mode. To confirm that this package is also valid for simulated ROI scanning, the DAP measurements made with static circular ROIs were compared against Monte Carlo simulations of the same ROI scanning modes.…”

“…A Monte Carlo package based on MC-GPU v1.3 and adapted for inverse geometry fluoroscopy 17 was used to simulate a moving elliptical ROI in DEC scanning. MC-GPU is a public domain Monte Carlo x-ray transport package based on the PENELOPE subroutine package.…”

Dynamic electronic collimation method for 3-D catheter tracking on a scanning-beam digital x-ray system

“…The dose reduction associated with a moving elliptical ROI was evaluated using a Monte Carlo simulation package developed for the SBDX geometry. 22 This simulation package has been previously validated against relative DAP measurements performed in RAE versus full FOV scanning mode. To confirm that this package is also valid for simulated ROI scanning, the DAP measurements made with static circular ROIs were compared against Monte Carlo simulations of the same ROI scanning modes.…”

“…A Monte Carlo package based on MC-GPU v1.3 and adapted for inverse geometry fluoroscopy 22 was used to simulate a moving elliptical ROI in DEC scanning. MC-GPU is a public domain Monte Carlo x-ray transport package based on the PENELOPE subroutine package.…”