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首页> 外文会议>Annual Symposium on Quantitative Nondestructive Evaluation; 19980719-24; Snowbird,UT(US) >VERIFICATION OF DETERMINISTIC SCATTERING COMPUTATIONS AND SOME OBSERVATIONS
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VERIFICATION OF DETERMINISTIC SCATTERING COMPUTATIONS AND SOME OBSERVATIONS

机译：确定性散射计算的验证和一些观测

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摘要

Scattering of the x-ray photons by the test object constitutes one of the most important physical mechanisms having a significant impact on radiographic image. Depending upon equipment setup, inspection parameters and material of the test object, contribution of scattering to the photon intensity may vary from a few percent of the overall beam incident upon the detector to more than half of the overall beam intensity. Therefore, a quantitative understanding of mechanics of scattering is an important issue in implementation of existing radiographic procedures and development of new ones. Development of computational models simulating scattering in radiographic studies provides the means for quantitative study of scattering phenomena. In addition to parametric studies enabled by such computational models, existence of such codes can also be utilized by the radiography simulators which have been gaining significant visibility in the last decade. The work presented here involves verification of the results provided by an computational method based on integral transport equation. Computational methods in photon transport are based on two major approaches. One of this is the stochastic approach leading to Monte Carlo type computations. Although Monte Carlo computations are known to provide quite accurate results for a large set of problems, they also come with certain drawbacks. Long computer execution times, relative inflexibility in test object geometry representation, difficulties in obtaining spatial flux distributions and difficulties in penetration problems can be counted among those drawbacks. The second one is the deterministic approach based on the transport equation. The deterministic computational method forming subject of this work provides a good alternative to Monte Carlo methods due to its flexibility in part geometry representation, execution speed and image formation. For transport equation solutions to be viable solutions, they should provide adequate accuracy. This work provides comparisons between our computational method and Monte Carlo code MCNP. After the comparisons, code is used for studying various scattering related issues in radiography.
机译：测试对象对X射线光子的散射是对射线照相图像有重大影响的最重要的物理机制之一。取决于设备设置，检查参数和测试对象的材料，散射对光子强度的贡献可能从入射到检测器上的总光束的百分之几到总光束强度的一半以上变化。因此，对散射力学的定量理解是实施现有射线照相程序和开发新射线照相程序的重要问题。在射线照相研究中模拟散射的计算模型的开发提供了定量研究散射现象的手段。除了通过这种计算模型进行的参数研究之外，射线照相模拟器还可以利用这种代码的存在，在过去的十年中，射线照相模拟器已经获得了显着的知名度。本文介绍的工作涉及对基于积分输运方程的计算方法所提供结果的验证。光子传输中的计算方法基于两种主要方法。其中之一是导致蒙特卡洛类型计算的随机方法。尽管已知蒙特卡洛计算可为大量问题提供非常准确的结果，但它们也存在某些缺点。在这些缺点中，可以算出较长的计算机执行时间，测试对象的几何形状表示相对不灵活，获得空间通量分布的困难以及穿透问题的困难。第二种是基于输运方程的确定性方法。确定性计算方法的形成是这项工作的主题，因为它在零件几何表示，执行速度和图像形成方面具有灵活性，因此可以很好地替代Monte Carlo方法。为了使运输方程解成为可行的解决方案，它们应提供足够的精度。这项工作提供了我们的计算方法和蒙特卡洛代码MCNP之间的比较。经过比较，代码被用于研究射线照相中与散射有关的各种问题。

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