A novel technique for measuring the low-dose envelope of pencil-beam scanning spot profiles
A novel technique for measuring the low-dose envelope of pencil-beam scanning spot profiles
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DOI：
10.1088/0031-9155/58/12/n171
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发表时间：
2013-06-21
影响因子：
3.5
通讯作者：
McDonough, James E.
中科院分区：
文献类型：
--
作者：
Lin, Liyong;Ainsley, Christopher G.;McDonough, James E.
为了研究IBA-Dosimetry闪烁探测器的轮廓测量能力，并评估其用于确定闪烁束扫描点的低强度尾部的可行性，在等中心处的空气中测量闪烁探测器和Gafchromic EBT 2膜对115 MeV质子点的响应。进行了成对的辐照：一次低水平辐照不足以引起饱和，一次高水平辐照故意使光斑的中心区域饱和，但提供了尾部的放大。通过采用配对/放大技术，可以将膜和闪烁探测器测量的光斑轮廓之间的一致性从中心光斑剂量的4%扩展到0.01%。这些测量值之间的伽马分析显示，使用3 mm/3%和5 mm/5%的标准，在+/- 9 cm范围内的一致性分别为95%和99%。高于4%，我们的115 MeV质子斑点可以很好地描述高斯函数;低于4%，非高斯，菱形尾巴占主导地位。
To investigate the profile measurement capabilities of an IBA-Dosimetry scintillation detector and to assess its feasibility for determining the low-intensity tails of pencil-beam scanning spots, the responses of the scintillation detector and Gafchromic EBT2 film to a 115 MeV proton spot were measured in-air at the isocenter. Pairs of irradiations were made: one lower-level irradiation insufficient to cause saturation, and one higher-level irradiation which deliberately saturated the central region of the spot, but provided magnification of the tails. By employing the pair/magnification technique, agreement between the film and scintillation detector measurements of the spot profile can be extended from 4% of the central spot dose down to 0.01%. Gamma analysis between these measurements shows 95% and 99% agreement within a +/- 9 cm bound using criteria of 3 mm/3% and 5 mm/5%, respectively. Above 4%, our 115 MeV proton spot can be well-described by Gaussian function; below 4%, non-Gaussian, diamond-shaped tails predominate.