New treatments in radiotherapy have some difficulties, among them, the geometric and dosimetric characterization of the radiation beam and the use of small radiation fields. Determination of the prescribed dose in the target volume in cases of small fields is difficult due to the absence of lateral electronic equilibrium and the sharp dose gradient at the edges of the fields. In this way, the choice of the radiation detector becomes relevant when performing the dosimetry of small fields. Alanine dosimeters have proven to be a good option for measurements of high radiation doses in these field sizes. This work aims to characterize the alanine detector through dosimetric tests for the VMAT (Volumetric Modulated Arc Therapy) technique in cases of SBRT (Stereotactic Body Radiation Therapy) to demonstrate the feasibility of using the alanine dosimetric system for use in quality control. End-to-End test was performed in a phantom, simulating two situations: homogeneous and heterogeneous regions. The response of L-alanine showed a strong linear correlation with dose (R = 0.99997), and insignificant dependence to dose rate. In the End-to-End test for a planned dose of 18 Gy, the doses obtained in alanine presented expanded uncertainty of 4.60% at 95% confidence level. Therefore, this work demonstrated that alanine dosimeter is suitable for quality control of SBRT with the VMAT technique in routine applications.

中文翻译：

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L-丙氨酸检测器的表征和实施，用于使用 VMAT 技术进行肺部 SBRT 治疗的质量控制

放射治疗中的新疗法存在一些困难，其中包括辐射束的几何和剂量学特征以及小辐射场的使用。在小射野的情况下，由于缺乏横向电子平衡以及射野边缘处的急剧剂量梯度，很难确定目标体积中的规定剂量。这样，在进行小射野剂量测定时，辐射探测器的选择就变得很重要。丙氨酸剂量计已被证明是在这些射野尺寸中测量高辐射剂量的良好选择。这项工作旨在通过 SBRT（立体定向身体放射治疗）情况下 VMAT（体积调制电弧疗法）技术的剂量测定测试来表征丙氨酸检测器，以证明使用丙氨酸剂量测定系统用于质量控制的可行性。在模型中进行端到端测试，模拟两种情况：同质区域和异质区域。 L-丙氨酸的响应与剂量呈很强的线性相关性（R = 0.99997），并且对剂量率的依赖性不显着。在计划剂量 18 Gy 的端到端测试中，丙氨酸获得的剂量在 95% 置信水平下呈现出 4.60% 的扩展不确定性。因此，这项工作证明丙氨酸剂量计适合在常规应用中使用 VMAT 技术进行 SBRT 的质量控制。