3 March 2012 Monte Carlo simulation of photon energy and dose-image quality in x-ray imaging
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Abstract
The purpose of this study was to investigate the role of x-ray photon energy in determining skin dose, energy imparted and image quality in diagnostic radiology. An irradiation geometry consisting of a monoenergetic x-ray source (40 to 80 keV), a 20×20×20 cm3 water cube and an image plane was modeled using MCNP5. At the center of the water cube was a 2×0.001×20 cm3 rectangular prism filled with iodine for imaging contrast. Contrast, noise, and contrast-to-noise ratio (CNR) were obtained for imaging under three scenarios: 1) with perfect grids; 2) with 8:1 grids (10% scatter, 70% primary beam) and 3) without grids at different incident photon energies. Under the same amount of incident photons, doubling photon energy from 40 to 80 keV caused a 19% increase in the total energy imparted and a 24% decrease in skin dose, with the lowest skin dose reached at ~70 keV. When the CNR was kept constant, the minimum energy imparted was achieved at 40 keV, while the minimum skin dose was achieved around 40~50 keV. When increasing the incident photon energy from 40 to 80 keV under a fixed CNR, skin dose increased ~480% and total energy imparted increased ~750% on average. Comparing with the imaging process without grids, the utilization of 8:1 grids decreased doses by ~84% at a fixed CNR. Under a constant image quality, the lowest skin dose and energy imparted may be achieved at different energy levels.
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Wenjun He, Wenjun He, Eugene Mah, Eugene Mah, Walter Huda, Walter Huda, Hai Yao, Hai Yao, } "Monte Carlo simulation of photon energy and dose-image quality in x-ray imaging", Proc. SPIE 8313, Medical Imaging 2012: Physics of Medical Imaging, 83135C (3 March 2012); doi: 10.1117/12.911232; https://doi.org/10.1117/12.911232
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