A radiation field is considered small if its dimension is lower than the range of secondary electrons and the collimating devices partially occlude the source. Different detector types, such as unshielded diodes, diamond detectors, and small-volume ion chambers, are used for small-field measurements. Although the active volumes of these detectors are small, their non-water equivalent materials cause response variations. Herein, we aim to calculate the correction factors for our clinical detectors, EDGE detector (Sun Nuclear), 60017 diode (PTW), and CC01 ion chamber (IBA), for stereotactic radiosurgery cones of diameters of 5–15 mm in an Elekta Synergy linear accelerator using a Monte Carlo simulation. An Elekta Synergy linear accelerator treatment head was simulated using BEAMnrc Monte Carlo code as per the manufacturer specification. All three detectors were simulated as per the manufacturer specification. Three EGSnrc user codes were used for the detector simulation based on the detector geometry. The Monte Carlo model of the treatment head was validated against the measured data for a standard field size of 10נ10 cm². The off-axis profile, percentage depth dose, and tissue phantom ratio were verified in the validation procedure. The measured and Monte Carlo calculated relative output factors (ROFs) were not consistent. In a 5 mm field size, EDGE diode overestimated the ROF by 7.06%, and 60017 diode to 4.611%. In a 7.5 mm field size, the variations were 4.295% and 3.691% for EDGE and 60017 diodes, respectively. CC01 ion chamber under-responded up to 10% because of its low-density active volume. The maximum corrections were obtained in the smallest field size, which were 0.939(0.007), 0.962(0.006), and 1.117(0.008) for EDGE, PTW T60017, and CC01 detectors, respectively. After applying the Monte Carlo calculated correction factor to the measured ROF, it became consistent with the Monte Carlo calculated ROF.

如果辐射场的尺寸低于二次电子的范围并且准直装置部分遮挡了源，则认为辐射场很小。不同的检测器类型，例如非屏蔽二极管、金刚石检测器和小体积离子室，用于小场测量。尽管这些探测器的有效体积很小，但它们的非水等效材料会引起响应变化。在此，我们旨在计算我们的临床检测器、EDGE 检测器 (SunNuclear)、60017 二极管 (PTW) 和 CC01 离子室 (IBA) 的校正因子，用于 Elekta Synergy 中直径为 5-15 毫米的立体定向放射外科锥体使用蒙特卡罗模拟的直线加速器。根据制造商规范，使用 BEAMnrc Monte Carlo 代码模拟 Elekta Synergy 直线加速器处理头。所有三个探测器都按照制造商的规格进行了模拟。三个 EGSnrc 用户代码用于基于探测器几何结构的探测器模拟。治疗头的蒙特卡罗模型根据 10 尺 10 厘米标准场尺寸的测量数据进行了验证² . 在验证程序中验证了离轴轮廓、深度剂量百分比和组织体模比率。测量的和蒙特卡罗计算的相对输出因子 (ROF) 不一致。在 5 mm 的场尺寸中，EDGE 二极管高估了 ROF 7.06%，而 60017 二极管高估了 4.611%。在 7.5 mm 的场尺寸中，EDGE 和 60017 二极管的变化分别为 4.295% 和 3.691%。CC01 离子室由于其低密度活性体积而反应不足达 10%。在最小视场尺寸下获得最大校正，EDGE、PTW T60017 和 CC01 探测器分别为 0.939(0.007)、0.962(0.006) 和 1.117(0.008)。将 Monte Carlo 计算的校正因子应用于测量的 ROF 后，它与 Monte Carlo 计算的 ROF 一致。