最佳双壁103Pd近距离放射治疗源的剂量学特征。

Dosimetric characteristics of the bests double-wall 103Pd brachytherapy source.

作者信息

Meigooni A S, Bharucha Z, Yoe-Sein M, Sowards K

机构信息

Department of Radiation Medicine, University of Kentucky Medical Center, Lexington 40536-0084, USA.

出版信息

Med Phys. 2001 Dec;28(12):2568-75. doi: 10.1118/1.1414007.

DOI:10.1118/1.1414007

PMID:11797962

Abstract

103Pd and 125I brachytherapy sources are being used for interstitial implants in tumor sites such as the prostate. Recently, a double-wall 103Pd source has been introduced, which has a design different from that of sources presently on the market. Dosimetric characteristics (dose rate constant, radial dose function, and anisotropy function) of this source were experimentally and theoretically determined following the AAPM Task Group 43 recommendations and were related to the October 10, 2000 revision of the NIST 1999 SK Standard for 103Pd. Measurements were performed in a Solid Water phantom using LiF thermoluminescent dosimeters. For these measurements, slabs of Solid Water phantom material were machined to accommodate the source and LiF TLD chips of dimensions (3.1 x 3.1 x 0.8 mm3) and (1.0 x 1.0 x 1.0 mm3). The TLD chips were surrounded by at least 10 cm of Solid Water phantom material to provide full scattering conditions. The Monte Carlo simulations were performed in Solid Water and liquid water using the PTRAN code. The results of this investigation show an excellent agreement (within 5%) between the measured (0.67+/-8% cGy h(-1) U(-1)) and calculated (to be 0.65+/-3% cGy h(-1) U(-1)) dose rate constant in Solid Water. The Monte Carlo calculated dose rate constant of the Best 103Pd in water was found to be 0.67+/-0.02 cGy h(-1) U(-1). The radial dose function, g(r), of the new 103Pd source was measured at distances ranging from 0.5 and 7 cm using LiF TLD in Solid Water phantom material. Moreover, the radial dose function of the new source was calculated in liquid water and Solid Water at distances ranging from 0.1 to 7 cm using the PTRAN Monte Carlo Code. The anisotropy function, F(r, theta), of the new 103Pd source was also measured in Solid Water and calculated in both Solid Water and water phantom material. From the anisotropy functions, the anisotropy factors, and anisotropy constant were calculated for each medium. The results indicated that the measured anisotropy constant of the Best 103Pd source in Solid Water was 0.89+/-5%. Complete dosimetric data are described in this manuscript.

摘要

103Pd和125I近距离放射治疗源正被用于前列腺等肿瘤部位的间质植入。最近，一种双壁103Pd源被引入，其设计与目前市场上的源不同。按照美国医学物理学家协会任务组43的建议，通过实验和理论确定了该源的剂量学特征（剂量率常数、径向剂量函数和各向异性函数），并与2000年10月10日美国国家标准与技术研究院1999年103Pd的SK标准修订版相关。使用LiF热释光剂量计在固体水模体中进行测量。对于这些测量，将固体水模体材料的板加工成适合源以及尺寸为（3.1×3.1×0.8 mm3）和（1.0×1.0×1.0 mm3）的LiF热释光剂量计芯片。热释光剂量计芯片被至少10 cm的固体水模体材料包围，以提供充分散射条件。使用PTRAN代码在固体水和液体水中进行蒙特卡罗模拟。本研究结果表明，在固体水中测量的剂量率常数（0.67±8% cGy h-1 U-1）与计算值（0.65±3% cGy h-1 U-1）之间具有良好的一致性（在5%以内）。发现蒙特卡罗计算的水中Best 103Pd的剂量率常数为0.67±0.02 cGy h-1 U-1。使用固体水模体材料中的LiF热释光剂量计在0.5至7 cm的距离范围内测量了新型103Pd源的径向剂量函数g(r)。此外，使用PTRAN蒙特卡罗代码在0.1至7 cm的距离范围内在液体水和固体水中计算了新型源的径向剂量函数。还在固体水中测量了新型103Pd源的各向异性函数F(r,θ)，并在固体水和水模体材料中进行了计算。根据各向异性函数，计算了每种介质的各向异性因子和各向异性常数。结果表明，在固体水中测量的Best 103Pd源的各向异性常数为0.89±5%。本手稿中描述了完整的剂量学数据。