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3 March 2012 Monte Carlo simulation of photon energy and dose-image quality in x-ray imaging
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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.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Wenjun He, Eugene Mah, Walter Huda, and 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);

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