Dosimetric IMRT verification with a flat-panel EPID
Dosimetric IMRT verification with a flat-panel EPID
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DOI：
10.1118/1.1625440
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发表时间：
2003-12-01
期刊：
影响因子：
3.8
通讯作者：
Fallone, BG
中科院分区：
文献类型：
--
作者：
Warkentin, B;Steciw, S;Fallone, BG
一个基于卷积的校准程序已经开发使用非晶硅平板电子射野成像设备（EPID）的强度调制放射治疗（IMRT）治疗的准确剂量学验证。原始EPID图像进行反卷积，以准确的，高分辨率的2-D分布的初级通量使用的散射内核组成的两个元素：蒙特卡罗生成的内核描述剂量沉积在EPID磷光体，和经验推导的内核描述光学光子扩散。EPID测量的相对通量分布与金刚石探测器测量的结果非常一致，并表现出良好的空间分辨率所需的调强放射治疗验证。对于剂量学验证，EPID测量的初级注量与描述固体水体模中剂量沉积的Monte Carlo核卷积，并与离子室测量交叉校准。对于2X2 cm（2）和10 X10 cm（2）的开放野，使用EPID测量的剂量分布与使用胶片测量的剂量分布在2.1%以内。基于我们的散射核，EPID体模散射因子（S-PE）的预测值在16 X16 cm（2）的开放视野尺寸下测量的S-PE的1%以内。使用EPID进行分步照射IMRT治疗的治疗前验证与使用胶片进行的治疗前验证具有良好的一致性，三次IMRT治疗（24个射野）的平均百分比差异为0.2 ± 1.0%。(C)2003年美国医学物理学家协会。
A convolution-based calibration procedure has been developed to use an amorphous silicon flat-panel electronic portal imaging device (EPID) for accurate dosimetric verification of intensity-modulated radiotherapy (IMRT) treatments. Raw EPID images were deconvolved to accurate, high-resolution 2-D distributions of primary fluence using a scatter kernel composed of two elements: a Monte Carlo generated kernel describing dose deposition in the EPID phosphor, and an empirically derived kernel describing optical photon spreading. Relative fluence profiles measured with the EPID are in very good agreement with those measured with a diamond detector, and exhibit excellent spatial resolution required for IMRT verification. For dosimetric verification, the EPID-measured primary fluences are convolved with a Monte Carlo kernel describing dose deposition in a solid water phantom, and cross-calibrated with ion chamber measurements. Dose distributions measured using the EPID agree to within 2.1% with those measured with film for open fields of 2X2 cm(2) and 10X10 cm(2). Predictions of the EPID phantom scattering factors (S-PE) based on our scatter kernels are within 1% of the S-PE measured for open field sizes of up to 16X16 cm(2). Pretreatment verifications of step-and-shoot IMRT treatments using the EPID are in good agreement with those performed with film, with a mean percent difference of 0.2+/-1.0% for three IMRT treatments (24 fields). (C) 2003 American Association of Physicists in Medicine.