放射变色胶片剂量学中横向响应伪影的显式像素值校正：单通道、双通道和三通道方法的评估

中文摘要 AI 辅助

背景：平板扫描仪会在垂直于灯运动的方向上引入横向响应伪影（LRA）。由于LRA随位置、像素值（PV）、颜色通道和胶片型号而变化，它可能违反多通道剂量学中通道共同扰动的假设。目的：表征EBT4和EBT-XD胶片在PV域中的LRA，比较Lewis和Full两种校正方法，并评估它们对单通道、双通道和三通道剂量学的影响。方法：使用循环移位设计，在七个横向位置上扫描七张胶片。对于每个位置和RGB通道，中心等效响应被建模为PVc = A + B * PV。Lewis校正使用两张胶片，对A和B进行线性插值；Full校正使用所有中心-局部配对，对PVc - PV进行PCHIP插值。通过纵向-横向剖面一致性和剂量准确性评估性能。结果：LRA在PV上是仿射的，关于扫描仪中心不对称，并依赖于胶片型号和通道。两种校正均减少了剖面差异。跨MU水平的平均绝对剖面差异，EBT4为1.4%-5.3%，EBT-XD为2.4%-6.8%。两种方法在EBT4上表现相似，而Full校正减少了EBT-XD若干双通道和三通道方法的差异。残留的蓝色通道误差限制了蓝色、红蓝和三通道的性能。在500 MU及以上时，红色通道显示出最佳的剂量一致性；在100 MU时，两种校正均增加了若干单通道估计的偏差。Full校正在若干EBT-XD条件下比Lewis产生更小的偏差。结论：LRA应在剂量重建之前在原始PV域中进行校正。Full校正更好地保持了剖面一致性和剂量准确性，尤其对于EBT-XD。由于改善的剖面一致性并不总是改善中心剂量一致性，因此在调试中应分别评估两者。

英文摘要

Background:Flatbed scanners introduce a lateral response artifact (LRA) perpendicular to lamp motion. Because LRA varies with position, pixel value (PV), color channel, and film model, it may violate the channel-common perturbation assumption of multichannel dosimetry. Purpose:To characterize PV-domain LRA in EBT4 and EBT-XD films, compare Lewis and Full corrections, and evaluate their effects on single-, double-, and triple-channel dosimetry. Methods:Seven films were scanned at seven lateral positions using a cyclic-shift design. For each position and RGB channel, center-equivalent response was modeled as PVc = A + B * PV. Lewis correction used two films with linear interpolation of A and B; Full correction used all center-local pairs with PCHIP interpolation of PVc - PV. Performance was assessed by portrait-landscape profile consistency and dose accuracy. Results: LRA was affine in PV, asymmetric about scanner center, and dependent on film model and channel. Both corrections reduced profile differences. Mean absolute profile differences across MU levels ranged from 1.4%-5.3% for EBT4 and 2.4%-6.8% for EBT-XD. The methods performed similarly for EBT4, while Full correction reduced discrepancies for several EBT-XD double- and triple-channel methods. Residual blue-channel errors limited blue, red-blue, and triple-channel performance. At 500 MU and above, red showed the best dose agreement; at 100 MU, both corrections increased deviations for several single-channel estimates. Full correction produced smaller deviations than Lewis in several EBT-XD conditions. Conclusions:LRA should be corrected in the raw-PV domain before dose reconstruction. Full correction better preserved profile consistency and dose accuracy, particularly for EBT-XD. Because improved profile consistency did not always improve central-dose agreement, both should be evaluated separately in commissioning.

发表机构

• University of Texas Southwestern Medical Center（德克萨斯大学西南医学中心）
• University of Florida（佛罗里达大学）

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