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11 June 1985 Monte Carlo Studies Of Image Spread By X-Ray Intensifying Screens
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Though intensifying screens reduce patient exposure, they also spread a point source of x-rays into a radial distribution of emitted light. The point spread function of the screen can be approximately decomposed into a portion due to scattering of the emitted light and a portion due to reabsorption of secondary x-rays. A random walk model is introduced to explain the dependence of light spread on scattering length and on the depth in the screen where the light is emitted. Monte Carlo simulations are used to find both the spatial spread of secondary x-rays and the fraction of photons that results from reabsorption of secondaries. These secondary x-ray parameters depend on (1} incident x-ray spectrum, (2) phosphor composition, (3) phosphor loading, and (4) screen thickness. These dependences are shown (for 60 - 120 kVp x-rays) for conventional phosphors, for Se, and for CsI. Finally, the magnitudes of secondary x-ray spread and of light spread are compared.
© (1985) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ed Caruthers "Monte Carlo Studies Of Image Spread By X-Ray Intensifying Screens", Proc. SPIE 0535, Application of Optical Instrumentation in Medicine XIII, (11 June 1985);

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