Photon energy spectrum emitted by a novel polymer-encapsulated 103Pd source and its effect on the dose rate constant.
Photon energy spectrum emitted by a novel polymer-encapsulated 103Pd source and its effect on the dose rate constant.
复制标题
新型聚合物封装 103Pd 源发射的光子能谱及其对剂量率常数的影响。
DOI：
10.1118/1.2870231
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发表时间：
2008
期刊：
影响因子：
3.8
通讯作者：
Nath,Ravinder
中科院分区：
文献类型：
--
作者：
Khan,Sabrina;Chen,ZheJay;Nath,Ravinder
两个独立的小组已经公布了最近推出的间质近距离放射治疗源，其中包含一种新型的聚合物外壳封装的内在剂量学参数。然而，两组报告的剂量率常数差异超过，目前在临床剂量测定中，该来源没有AAPM推荐的共识值。这项工作的目的是使用最近开发的光子光谱技术进行一个独立的确定的来源。本研究中使用了三个已知空气比释动能强度的源（型号1032 P）。在空气中使用为低能近距离放射治疗源光谱学设计和建立的高分辨率本征锗光谱仪测量沿源平分线上的径向发射的光子能谱。每个源的剂量率常数由其发射的能谱和源中放射性的空间分布确定。与传统钛封装的其他光源不同，该光源发射的光子仅表现出轻微的光谱硬化，产生的相对能谱更接近于裸光源发射的光子。用光子能谱技术测定了水的剂量率常数。在实验不确定性范围内，该值与Wang和Hertel报告的蒙特卡罗计算值和蒙特卡罗测量值（采用蒙特卡罗计算的固体体模-水转换因子）一致[Appl. Radiat.伊索特63，311-321（2005）]。然而，它与Bernard和Vynckier报道的不同[Phys. Med. Biol. 50，1493-1504（2005）]。在这项工作中获得的结果提供了额外的信息需要建立一个共识值的剂量率常数的源。这表明，源的最终共识值可能更接近于值，而不是源制造商基于先前发表的两个结果最初推荐的值。
Two independent groups have published intrinsic dosimetry parameters for the recently introduced interstitial brachytherapy source which contains encapsulated by a novel polymer shell. The dose rate constant reported by the two groups, however, differed by more than and there is currently no AAPM recommended consensus value for this source in clinical dosimetry. The aim of this work was to perform an independent determination of for the source using a recently developed photon spectrometry technique. Three sources (model 1032P) with known air‐kerma strength were used in this study. The photon energy spectrum emitted along the radial direction on the source's bisector was measured in air using a high‐resolution intrinsic germanium spectrometer designed and established for low‐energy brachytherapy source spectrometry. The dose rate constant of each source was determined from its emitted energy spectrum and the spatial distribution of radioactivity in the source. Unlike other sources made with traditional titanium encapsulation, the photons emitted by the sources exhibited only slight spectral hardening, yielding a relative energy spectrum closer to that emitted by bare . The dose rate constant determined by the photon spectrometry technique for water was . This value agreed, within experimental uncertainties, with the Monte Carlo‐calculated value of and the TLD‐measured value (with a Monte Carlo‐calculated solid‐phantom‐to‐water conversion factor) of reported by Wang and Hertel [Appl. Radiat. Isot. 63, 311–321 (2005)]. However, it differed by from the of reported by Bernard and Vynckier [Phys. Med. Biol. 50, 1493–1504 (2005)]. The results obtained in this work provide additional information needed for establishing a consensus value for the dose rate constant for the source. It suggests that an eventual consensus value of for the source is likely to be closer to a value of rather than as initially recommended by the source manufacturer based on the two previously published results.