Cho Sang Hyun, Vassiliev Oleg N, Horton John L
Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Unit 94, Houston, TX 77030, USA.
Radiat Environ Biophys. 2007 Mar;46(1):77-83. doi: 10.1007/s00411-006-0086-8. Epub 2007 Jan 12.
An event-by-event Monte Carlo code called NOREC, a substantially improved version of the Oak Ridge electron transport code (OREC), was released in 2003, after a number of modifications to OREC. In spite of some earlier work, the characteristics of the code have not been clearly shown so far, especially for a wide range of electron energies. Therefore, NOREC was used in this study to generate one of the popular dosimetric quantities, the scaled point kernel, for a number of electron energies between 0.02 and 1.0 MeV. Calculated kernels were compared with the most well-known published kernels based on a condensed history Monte Carlo code, ETRAN, to show not only general agreement between the codes for the electron energy range considered but also possible differences between an event-by-event code and a condensed history code. There was general agreement between the kernels within about 5% up to 0.7 r/r (0) for 100 keV and 1 MeV electrons. Note that r/r (0) denotes the scaled distance, where r is the radial distance from the source to the dose point and r (0) is the continuous slowing down approximation (CSDA) range of a mono-energetic electron. For the same range of scaled distances, the discrepancies for 20 and 500 keV electrons were up to 6 and 12%, respectively. Especially, there was more pronounced disagreement for 500 keV electrons than for 20 keV electrons. The degree of disagreement for 500 keV electrons decreased when NOREC results were compared with published EGS4/PRESTA results, producing similar agreement to other electron energies.
一种名为NOREC的逐事件蒙特卡罗代码，它是橡树岭电子输运代码（OREC）的大幅改进版本，在对OREC进行了多次修改后于2003年发布。尽管有一些早期的工作，但到目前为止，该代码的特性尚未得到清晰展示，特别是对于宽范围的电子能量。因此，本研究使用NOREC来生成一种常用的剂量学量，即缩放点核，用于0.02至1.0 MeV之间的多种电子能量。将计算得到的核与基于凝聚历史蒙特卡罗代码ETRAN的最著名的已发表核进行比较，以展示不仅在所考虑的电子能量范围内代码之间的总体一致性，而且还展示逐事件代码和凝聚历史代码之间可能存在的差异。对于100 keV和1 MeV电子，在高达0.7 r/r(0)的范围内，核之间的总体一致性在约5%以内。请注意，r/r(0)表示缩放距离，其中r是从源到剂量点的径向距离，r(0)是单能电子的连续慢化近似（CSDA）范围。对于相同的缩放距离范围，20 keV和500 keV电子的差异分别高达6%和12%。特别是，500 keV电子的不一致性比20 keV电子更明显。当将NOREC结果与已发表的EGS4/PRESTA结果进行比较时，500 keV电子的不一致程度降低，与其他电子能量产生了类似的一致性。
