Monte Carlo simulation of the image formation process in portal imaging

Abstract

We have written Monte Carlo programs to simulate the formation of radiological images. Our code is used to propagate a simulated x-ray fluence through each component of an existing video-based portal imaging system. This simulated fluence consists of a 512 x 512 pixel image containing both contrast-detail patterns as well as checker patterns to assess spatial resolution of the simulated portal imager. All of the components of the portal imaging system were modeled as a cascade of eight linear stages. Using this code, one can assess the visual impact of changing components in the imaging chain by changing the appropriate probability density function. Virtual experiments were performed to assess the visual impact of replacing the lens and TV camera by an amorphous silicon array, and the effect of scattered radiation on portal images.

Monte Carlo analysis of megavoltage x-ray interaction-induced signal and noise in cadmium tungstate detectors for cargo container inspection

“…While high quality x-ray images, from which one identifies abnormal objects visually and quantitatively, are demanded, MV images are normally expected to suffer from poor quality due to high energy-absorption noise [6,7]. At MeV energies, the photoelectric events are less probable whereas Compton-scatter events are more, as shown in figure 1(b).…”

Patient-specific dosimetry of conventional and intensity modulated radiation therapy using a novel full Monte Carlo phase space reconstruction method from electronic portal images

“…Recently, MC simulations have been used to model portal imagers. The MC models were used to predict portal images (Siebers and Mohan 2004, Spezi and Lewis 2002, Jarry and Verhaegen 2005, Li et al 2006 and to study the image formation process (Bissonnette et al 2003). MC simulations were shown to predict reliably portal images of conventional photon and electron beams and IMRT fields.…”