University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany.
PTW-Freiburg, Freiburg, Germany.
Med Phys. 2019 Sep;46(9):4257-4262. doi: 10.1002/mp.13710. Epub 2019 Jul 31.
Dosimetric properties of the new microSilicon diode detector (60023) have been studied with focus on application in small-field dosimetry. The influences of the dimensions of the sensitive volume and the density of the epoxy layer surrounding the silicon chip of microSilicon have been quantified and compared to its predecessor (Diode E 60017) and the microDiamond (60019, all PTW-Freiburg, Germany).
Dose linearity has been studied in the range from 0.01 to 8.55 Gy and dose-per-pulse dependence from 0.13 to 0.86 mGy/pulse. The effective point of measurement (EPOM) was determined by comparing measured percentage depth dose curves with a reference curve (Roos chamber). Output ratios were measured for nominal field sizes from 0.5 × 0.5 cm to 4 × 4 cm . The corresponding small-field output correction factors, k, were derived with a plastic scintillation detector as reference. The lateral dose-response function, K(x), was determined using a slit beam geometry.
MicroSilicon shows linear dose response (R = 1.000) in both low and high dose range up to 8.55 Gy with deviations of only up to 1% within the dose-per-pulse values investigated. The EPOM was found to lie (0.7 ± 0.2) mm below the front detector's surface. The derived k for microSilicon (0.960 at s = 0.55 cm) is similar to that of microDiamond (0.956), while Diode E requires larger corrections (0.929). This improved behavior of microSilicon in small-fields is reflected in the slightly wider K(x) compared to Diode E. Furthermore, the amplitude of the negative values in K(x) at the borders of the sensitive volume has been reduced.
Compared to its predecessor, microSilicon shows improved dosimetric behavior with higher sensitivity and smaller dose-per-pulse dependence. Profile measurements demonstrated that microSilicon causes less perturbation in off-axis measurements. It is especially suitable for the applications in small-field output factors and profile measurements.
研究了新型微硅二极管探测器（60023）的剂量学特性，重点关注其在小场剂量学中的应用。定量研究了敏感体积尺寸和硅片周围环氧层密度对微硅的影响，并与前一代探测器（Diode E 60017）和微金刚石（60019，均为德国 PTW-Freiburg 公司产品）进行了比较。
研究了 0.01 至 8.55Gy 范围内的剂量线性度和 0.13 至 0.86mGy/脉冲范围内的剂量-脉冲依赖性。通过比较测量的百分深度剂量曲线与参考曲线（Roos 室），确定有效测量点（EPOM）。测量了标称场尺寸为 0.5×0.5cm 至 4×4cm 的输出比。用塑料闪烁探测器作为参考，得出相应的小场输出校正因子 k。用狭缝束几何形状确定横向剂量响应函数 K(x)。
微硅在低剂量和高剂量范围内（高达 8.55Gy）均呈现线性剂量响应（R=1.000），在研究的剂量-脉冲值范围内，偏差仅为 1%。发现 EPOM 位于前探测器表面以下（0.7±0.2）mm 处。微硅的 k 值（s=0.55cm 时为 0.960）与微金刚石相似（0.956），而 Diode E 需要更大的校正值（0.929）。微硅在小场中的这种改进的剂量学行为反映在与 Diode E 相比，K(x)稍宽。此外，敏感体积边界处 K(x)中负值的幅度已经减小。
与前一代相比，微硅具有更高的灵敏度和更小的剂量-脉冲依赖性，表现出更好的剂量学性能。轮廓测量表明，微硅在轴外测量中引起的干扰较小。它特别适用于小场输出因子和轮廓测量的应用。
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