Dosimetry characterization of 32P catheter-based vascular brachytherapy source wire.
Dosimetry characterization of 32P catheter-based vascular brachytherapy source wire.
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基于 32P 导管的血管近距离放射治疗源线的剂量测定特性。
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
S. H. Lott
中科院分区：
文献类型：
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作者：
F. Mourtada;C. Soares;S. Seltzer;S. H. Lott
描述了基于导管的32 P血管内近距离放射治疗源丝的剂量测量和蒙特卡罗模拟。使用辐射变色染料膜和自动塑料闪烁体获得测量的剂量率。所研究的源具有27 mm的长度和0.24 mm的直径的尺寸，并且封装在NiTi中。对于辐射变色膜测量，在A-150塑料中，在距源轴1至5 mm的距离处照射校准的辐射变色染料膜，并用高分辨率扫描密度计读出。在A-150中测得的深度-剂量曲线，然后转换为在水中使用从Monte Carlo计算获得的校正因子。对于闪烁体系统，在水中的直接测量是在距离源中心1至6 mm处采集的，沿着源轴的垂直平分线。闪烁体在多个深度的参考β粒子场中的闪烁剂量率方面进行校准。然后将从胶片和闪烁体测量获得的测量剂量率标准化为测量源活性，即，将测量数据转换为cGy/s/mCi单位。基于导管的32 P导丝几何结构的理论剂量学计算也是使用电子伽马簇射代码（EGS 4）、蒙特卡罗N粒子传输代码（MCNP 4 B）和集成Tiger系列代码（ITS v.3）的CYLTRAN从蒙特卡罗模拟中获得的，并且发现具有良好的一致性。测量和计算的结果均表示为每单位所含放射性在水中的累积剂量率（cGy/s/mCi）。比较表明，在相关治疗距离（1-5 mm）内，测量和计算的剂量测定具有良好的一致性（<10%）。这项工作充分表征了水中新型32 P β近距离放射治疗源周围的辐射场。深度-剂量曲线可用于计算从血管腔内居中的27 mm 32 P源导丝到血管壁的剂量。
Dosimetry measurements and Monte Carlo simulations for a catheter-based 32P endovascular brachytherapy source wire are described. The measured dose rates were obtained using both radiochromic dye film and an automated plastic scintillator. The investigated source has dimensions of 27 mm in length and 0.24 mm in diameter, and is encapsulated in NiTi. For the radiochromic film measurements, calibrated radiochromic dye film was irradiated at distances between 1 and 5 mm from the source axis in A-150 plastic, and read out with a high-resolution scanning densitometer. The depth-dose curve measured in A-150 is then converted to that in water using correction factors obtained from Monte Carlo calculations. For the scintillator system, direct measurements in water were acquired at distances between 1 and 6 mm from the center of the source, along the perpendicular bisector of the source axis. The scintillator was calibrated in terms of absorbed-dose rate in a reference beta-particle field at multiple depths. The measured dose rates obtained from the film and scintillator measurements were then normalized to the measured source activity, i.e., to convert the measured data to units of cGy/s/mCi. Theoretical dosimetry calculations of the catheter-based 32P wire geometry were also obtained from Monte Carlo simulations using the Electron Gamma Shower code (EGS4), the Monte Carlo N-particle transport code (MCNP4B), and CYLTRAN from the Integrated Tiger Series codes (ITS v.3) and found to be in good agreement. The results of both measurements and calculations are expressed as absorbed-dose rate in water per unit of contained activity (cGy/s/mCi). Comparisons indicate that the measured and calculated dosimetry are in good agreement (<10%) within the relevant treatment distances (1-5 mm). This work fully characterizes the radiation field around a novel 32P beta brachytherapy source in water. The depth-dose curve can be used to calculate the dose to the vessel wall from a 27 mm 32P source wire centered within the vessel lumen.