...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Physics in medicine and biology. >A Monte Carlo method to evaluate the impact of positioning errors on detector response and quality correction factors in nonstandard beams.
【24h】

A Monte Carlo method to evaluate the impact of positioning errors on detector response and quality correction factors in nonstandard beams.

机译：用于评估定位误差对非标准光束中探测器响应和质量校正因子的影响的蒙特卡洛方法。

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

During experimental procedures, an adequate evaluation of all sources of uncertainty is necessary to obtain an overall uncertainty budget. In specific radiation dosimetry applications where a single detector is used, common methods to evaluate uncertainties caused by setup positioning errors are not applicable when the dose gradient is not known a priori. This study describes a method to compute these uncertainties using the Monte Carlo method. A mathematical formalism is developed to calculate unbiased estimates of the uncertainties. The method is implemented in egs_chamber, an EGSnrc-based code that allows for the efficient calculation of detector doses and dose ratios. The correct implementation of the method into the egs_chamber code is validated with an extensive series of tests. The accuracy of the developed mathematical formalism is verified by comparing egs_chamber simulation results to the theoretical expectation in an ideal situation where the uncertainty can be computed analytically. Three examples of uncertainties are considered for realistic models of an Exradin A12 ionization chamber and a PTW 60012 diode, and results are computed for parameters representing nearly realistic positioning error probability distributions. Results of practical examples show that uncertainties caused by positioning errors can be significant during IMRT reference dosimetry as well as small field output factor measurements. The method described in this paper is of interest in the study of single-detector response uncertainties during nonstandard beam measurements, both in the scope of daily routine as well as when developing new dosimetry protocols. It is pointed out that such uncertainties should be considered in new protocols devoted to single-detector measurements in regions with unpredictable dose gradients. The method is available within the egs_chamber code in the latest official release of the EGSnrc system.
机译：在实验过程中，必须对所有不确定性来源进行充分评估，以获得总体不确定性预算。在使用单个检测器的特定辐射剂量测定应用中，当先验未知剂量梯度时，评估由设置定位误差引起的不确定性的通用方法不适用。这项研究描述了一种使用蒙特卡洛方法计算这些不确定性的方法。建立了数学形式主义以计算不确定性的无偏估计。该方法在egs_chamber中实现，egs_chamber是基于EGSnrc的代码，可以有效计算检测器剂量和剂量比。该方法在egs_chamber代码中的正确实现已通过一系列广泛的测试进行了验证。通过将egs_chamber模拟结果与理想情况下的理论期望值进行比较，可以验证所开发的数学形式主义的准确性，在理想情况下可以通过分析来计算不确定性。对于Exradin A12电离室和PTW 60012二极管的真实模型，考虑了三个不确定性示例，并对代表几乎真实的定位误差概率分布的参数计算了结果。实际示例的结果表明，在IMRT参考剂量测定以及小场输出因子测量期间，由定位误差引起的不确定性可能非常明显。本文介绍的方法在非标准光束测量过程中的单探测器响应不确定性研究中很有用，无论是在日常范围内还是在开发新的剂量学协议时。应当指出，在专门用于具有不可预测的剂量梯度的区域中的单探测器测量的新协议中，应考虑此类不确定性。该方法在EGSnrc系统的最新官方发行版的egs_chamber代码中可用。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号