Theoretical and empirical investigations of KCl : Eu2+ for nearly water-equivalent radiotherapy dosimetry.
Theoretical and empirical investigations of KCl : Eu2+ for nearly water-equivalent radiotherapy dosimetry.
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KCl : Eu2 用于近水当量放射治疗剂量测定的理论和实证研究。
DOI：
10.1118/1.3271338
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发表时间：
2010
期刊：
影响因子：
3.8
通讯作者：
Li,HHarold
中科院分区：
文献类型：
--
作者：
Zheng,Yuanshui;Han,Zhaohui;Driewer,JosephP;Low,DanielA;Li,HHarold
目的低有效原子序数、可重用性和其他与计算机射线照相相关的优点使掺Eu的氯化钾成为一种很有前途的剂量学材料。本研究的目的是用蒙特卡罗(MC)方法建立点剂量计的模型，并利用该模型研究二维(2D)存储荧光粉薄膜(SPF)的剂量响应。将测量到的剂量与电离室测量的剂量进行比较，得到能量相关剂量测量伪影的大小。利用BEAMnrcMP生成的相空间文件，用DOSXYZnrc对测量结果进行了模拟。对厚度在以下范围的薄膜也进行了模拟。原型材料的功函数是通过比较厚膜和具有已知功函数的商用SPF的灵敏度来确定的。结果原型点剂量计的模拟剂量响应与在不同视场大小和深度的束流中照射剂量计所获得的测量数据吻合较好。此外，对薄膜的模拟表明，厚度约为数量级的超薄膜将具有几乎相当于水的剂量响应。模拟结果可以用经典的腔体理论来理解。最后，初步的实验和理论计算表明，超薄膜可以在剂量到水的照射中提供良好的信号。结论作者证明，基于MC的剂量计可以用MC方法准确地建模，并且厚度量级的2D薄膜对能量的依赖性最小。这些数据支持未来基于存储磷光体的定量、高分辨率多维放射治疗剂量测量系统的研究和开发。
PurposeThe low effective atomic number, reusability, and other computed radiography‐related advantages make europium doped potassium chloride a promising dosimetry material. The purpose of this study is to model point dosimeters with a Monte Carlo (MC) method and, using this model, to investigate the dose responses of two‐dimensional (2D) storage phosphor films (SPFs).Methodspoint dosimeters were irradiated using a beam at four depths for each of five square field sizes . The dose measured by was compared to that measured by an ionization chamber to obtain the magnitude of energy dependent dose measurement artifact. The measurements were simulated using DOSXYZnrc with phase space files generated by BEAMnrcMP. Simulations were also performed for films with thicknesses ranging from . The work function of the prototype material was determined by comparing the sensitivity of a thick film to a commercial ‐based SPF with a known work function. The work function was then used to estimate the sensitivity of a thick film.ResultsThe simulated dose responses of prototype point dosimeters agree well with measurement data acquired by irradiating the dosimeters in the beam with varying field size and depth. Furthermore, simulations with films demonstrate that an ultrathin film with thickness of the order of would have nearly water‐equivalent dose response. The simulation results can be understood using classic cavity theories. Finally, preliminary experiments and theoretical calculations show that ultrathin film could provide excellent signal in a dose‐to‐water irradiation.ConclusionsIn conclusion, the authors demonstrate that ‐based dosimeters can be accurately modeled by a MC method and that 2D films of the order of thick would have minimal energy dependence. The data support the future research and development of a storage phosphor‐based system for quantitative, high‐resolution multidimensional radiation therapy dosimetry.