Experimental evaluation of x-ray acoustic computed tomography for radiotherapy dosimetry applications
Experimental evaluation of x-ray acoustic computed tomography for radiotherapy dosimetry applications
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DOI：
10.1002/mp.12039
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发表时间：
2017-02-01
期刊：
影响因子：
3.8
通讯作者：
El Naqa, Issam
中科院分区：
文献类型：
--
作者：
Hickling, Susannah;Lei, Hao;El Naqa, Issam
目的：这项工作的目的是通过实验证明 X 射线声学计算机断层扫描 (XACT) 作为临床放射治疗环境中剂量测定工具的可行性。方法：使用浸入式超声换能器检测水箱中直线加速器照射单脉冲后诱发的声波。通过旋转准直器并保持换能器静止，检测并重建场周围不同角度的声信号，以形成 XACT 图像。模拟 XACT 图像是使用先前开发的模拟工作流程获得的。从实验和模拟 XACT 图像中提取的轮廓与使用电离室测量的轮廓进行比较。研究了各种辐射场尺寸和形状。结果：获得了与所传递的辐射场几何形状相似的 XACT 图像，范围从简单的正方形到更复杂的形状。当比较从 4 cm x 4 cm 区域的模拟和实验 XACT 图像中提取的轮廓时，发现 97% 的点通过了 3%/3 mm 伽玛测试。当比较具有精细细节的场时，模拟和实验 XACT 图像之间的一致性恶化。将从实验 XACT 图像中提取的轮廓与通过临床电离室测量获得的轮廓进行比较，确认 XACT 图像的强度与沉积的辐射剂量相关。与电离室测量的轮廓相比，从 4 cm x 4 cm 场的实验 XACT 图像中提取的轮廓中，77% 的点通过了 7%/4 mm 伽玛测试。在复杂的拼图形状场中，XACT 提取轮廓中的 86% 的点通过了 7%/4 mm 伽马测试。 结论：针对各种场尺寸和形状形成了强度与水箱中沉积剂量的空间分布相关的 XACT 图像。 XACT 有潜力成为绝对、相对和体内剂量测定的有用工具。 (C) 2016年美国医学物理学家协会
Purpose: The aim of this work was to experimentally demonstrate the feasibility of x-ray acoustic computed tomography (XACT) as a dosimetry tool in a clinical radiotherapy environment.Methods: The acoustic waves induced following a single pulse of linear accelerator irradiation in a water tank were detected with an immersion ultrasound transducer. By rotating the collimator and keeping the transducer stationary, acoustic signals at varying angles surrounding the field were detected and reconstructed to form an XACT image. Simulated XACT images were obtained using a previously developed simulation workflow. Profiles extracted from experimental and simulated XACT images were compared to profiles measured with an ion chamber. A variety of radiation field sizes and shapes were investigated.Results: XACT images resembling the geometry of the delivered radiation field were obtained for fields ranging from simple squares to more complex shapes. When comparing profiles extracted from simulated and experimental XACT images of a 4 cm x 4 cm field, 97% of points were found to pass a 3%/3 mm gamma test. Agreement between simulated and experimental XACT images worsened when comparing fields with fine details. Profiles extracted from experimental XACT images were compared to profiles obtained through clinical ion chamber measurements, confirming that the intensity of XACT images is related to deposited radiation dose. Seventy-seven percent of the points in a profile extracted from an experimental XACT image of a 4 cm x 4 cm field passed a 7%/4 mm gamma test when compared to an ion chamber measured profile. In a complicated puzzle-piece shaped field, 86% of the points in an XACT extracted profile passed a 7%/4 mm gamma test.Conclusions: XACT images with intensity related to the spatial distribution of deposited dose in a water tank were formed for a variety of field sizes and shapes. XACT has the potential to be a useful tool for absolute, relative and in vivo dosimetry. (C) 2016 American Association of Physicists in Medicine