The dosimetric characterization of a commercial diode (BPW-34) was performed using a True Beam accelerator (Varian), with flattening filter (FF) photon beams of 6 and 15 MV and flattening filter free (FFF) of 6 MVFFF. The main performance characteristics, namely dose response, energy and dose rate dependence, field output factor, and percentage depth dose profile (PDD), were compared with those available in the literature and, whenever possible, benchmarked against the Varian Eclipse treatment planning system (TPS) predictions. Regardless of the energy, the results showed that the dose response curves are linear (R = 1) with nonlinearity parameters less than 0.1% and 0.3% of repeatability. Furthermore, the average dose rate effect (0.7%) is almost negligible within the range of 20–600 MU/min (6 MV, 15 MV) and 400–1400 MU/min (6 MVFFF). Despite these good results, the charge sensitivity measurements evidenced that the diode response depends slightly on the energy, being within 5% for 6 MV–15 MV. It is important to underline that all these results adhere to the standard radiotherapy dosimetry protocols. Moreover, the general output field factor measurements and the percentage depth dose profiles, which are in excellent agreement with the Eclipse TPS calculations, also demonstrated that the diode BPW-34 is a low-budget alternative radiotherapy photon beam dosimeter.

中文翻译：

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用于放射治疗光子束剂量测定的商用 PIN 二极管的表征

使用 True Beam 加速器 (Varian) 进行商用二极管 (BPW-34) 的剂量测定表征，其中平坦滤波器 (FF) 光子束为 6 和 15 MV，无平坦滤波器 (FFF) 为 6 MVFFF。主要性能特征，即剂量响应、能量和剂量率依赖性、场输出因子和百分比深度剂量分布 (PDD)，与文献中提供的那些进行了比较，并尽可能根据 Varian Eclipse 治疗计划系统进行基准测试（ TPS）预测。无论能量如何，结果表明剂量响应曲线是线性的（R = 1），非线性参数小于 0.1% 和重复性的 0.3%。此外，在20-600 MU/min（6 MV、15 MV）和400-1400 MU/min（6 MVFFF）范围内，平均剂量率影响（0.7%）几乎可以忽略不计。尽管取得了这些良好的结果，但电荷灵敏度测量结果表明，二极管响应对能量的依赖程度略有不同，对于 6 MV–15 MV，该响应在 5% 以内。需要强调的是，所有这些结果均符合标准放射治疗剂量测定方案。此外，一般输出场因子测量和百分比深度剂量分布与 Eclipse TPS 计算非常一致，也证明二极管 BPW-34 是一种低成本替代放射治疗光子束剂量计。