Abstract Purpose High dose prescription in one treatment session of intraoperative radiotherapy (IORT) requires precise monitoring of the delivered dose. Methacrylic acid, gelatin and tetrakis phosphonium chloride (MAGAT) gel with superior dose sensitivity and dose resolution seems to be a suitable tool for 3 dimensional dose verification of IORT. In the current study, the dose response of MAGAT gel dosimeter with varying concentrations of methacrylic acid (MAA) was investigated. Finally, the MAGAT with optimal concentration was subjected to dose rate and energy dependency measurements. Methods MAGAT gel with different concentrations of 3, 5, 6, 8 and 10% was manufactured and irradiated with 50 keV produced by IORT. Gel vials were read out by MRI and R2 responses were plotted against dose. Dose rate and energy dependency of optimum MAGAT gel were assessed by irradiation by a VARIAN linear accelerator using various dose rates of 30, 40 and 50 cGy/min and diverse photon energies of 6 and 18 MV as well as 50 keV of IORT. Results MAGAT with a concentration of 8% MAA, exhibited a high-dose response and dose sensitivity of 5.16 Gy−1 s−1 in irradiation by IORT. Moreover, its response was independent of low dose rates (30, 40 and 50 cGy/min) and mega-voltage energies (p > 0.05). However, there was a significant difference between the R2-dose response of MAGAT irradiated by mega-voltage (6 and 18 MV) and 50 keV energy of IORT. Conclusion MAGAT is an effective tool to investigate three dimensional dose distributions of IORT independent of dose rates used in X-ray IORT. Moreover, its response is energy independent over mega-voltage energies.

中文翻译：

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不同浓度甲基丙烯酸对术中放疗MAGAT凝胶剂量计剂量反应影响的新研究

摘要 目的 术中放疗 (IORT) 的一次治疗中的高剂量处方需要精确监测递送剂量。具有优异剂量敏感性和剂量分辨率的甲基丙烯酸、明胶和四氯化鏻 (MAGAT) 凝胶似乎是 IORT 3 维剂量验证的合适工具。在当前的研究中，研究了 MAGAT 凝胶剂量计对不同浓度的甲基丙烯酸 (MAA) 的剂量响应。最后，对具有最佳浓度的 MAGAT 进行剂量率和能量依赖性测量。方法制备3%、5%、6%、8%和10%不同浓度的MAGAT凝胶，并用IORT生产的50 keV辐照。凝胶小瓶通过 MRI 读出，R2 响应与剂量作图。最佳 MAGAT 凝胶的剂量率和能量依赖性通过 VARIAN 线性加速器使用 30、40 和 50 cGy/min 的各种剂量率和 6 和 18 MV 的不同光子能量以及 50 keV 的 IORT 进行辐照来评估。结果 8% MAA 的 MAGAT 在 IORT 照射中表现出高剂量反应和 5.16 Gy-1 s-1 的剂量敏感性。此外，它的反应与低剂量率（30、40 和 50 cGy/min）和兆电压能量（p > 0.05）无关。然而，在兆电压（6 和 18 MV）和 50 keV IORT 能量照射下，MAGAT 的 R2 剂量响应存在显着差异。结论 MAGAT 是研究 IORT 三维剂量分布的有效工具，与 X 射线 IORT 中使用的剂量率无关。而且，