Graduate School of Health Sciences, Kumamoto University, 4-24-1 Kuhonji, Chuo-ku, Kumamoto 862-0976, Japan.
Department of Health Sciences, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Chuo-ku, Kumamoto 862-0976, Japan.
Phys Med. 2021 Apr;84:198-204. doi: 10.1016/j.ejmp.2021.04.009. Epub 2021 May 12.
To determine the surface dose of a water phantom using a semiconductor detector for diagnostic kilovoltage x-ray beams.
An AGMS-DM+ semiconductor detector was calibrated in terms of air kerma measured with an ionization chamber. Air kerma was measured for 20 x-ray beams with tube voltages of 50-140 kVp and a half-value layer (HVL) of 2.2-9.7 mm Al for given quality index (QI) values of 0.4, 0.5, and 0.6, and converted to the surface dose. Finally, the air kerma and HVL measured by the AGMS-DM+ detector were expressed as a ratio of the surface dose for 10 × 10 and 20 × 20 cm fields. The ratio of both was represented as a function of HVL for the given QI values and verified by comparing it with that calculated using the Monte Carlo method.
The air kerma calibration factor, CF, for the AGMS-DM+ detector ranged from 0.986 to 1.016 (0.9% in k = 1). The CF values were almost independent of the x-ray fluence spectra for the given QI values. The ratio of the surface dose to the air kerma determined by the PTW 30,013 chamber and the AGMS-DM+ detector was less than 1.8% for the values calculated using the Monte Carlo method, and showed a good correlation with the HVL for the given QI values.
It is possible to determine the surface dose of a water phantom from the air kerma and HVL measured by a semiconductor detector for given QI values.
使用半导体探测器确定水模体的表面剂量，用于诊断千伏 X 射线束。
使用电离室测量空气比释动能，对 AGMS-DM+半导体探测器进行校准。针对给定的质量指数（QI）值 0.4、0.5 和 0.6，测量了管电压为 50-140 kVp、半值层（HVL）为 2.2-9.7 mm Al 的 20 个 X 射线束的空气比释动能，并将其转换为表面剂量。最后，AGMS-DM+探测器测量的空气比释动能和 HVL 表示为 10×10 和 20×20 cm 射野的表面剂量的比值。对于给定的 QI 值，用 HVL 表示这两个比值，并通过与蒙特卡罗方法计算的值进行比较来验证。
AGMS-DM+探测器的空气比释动能校准因子 CF 范围为 0.986-1.016（k=1 时为 0.9%）。对于给定的 QI 值，CF 值几乎与 X 射线通量谱无关。PTW 30,013 腔室和 AGMS-DM+探测器测量的空气比释动能与表面剂量的比值，使用蒙特卡罗方法计算的值小于 1.8%，并且与给定 QI 值的 HVL 具有良好的相关性。
对于给定的 QI 值，可以从半导体探测器测量的空气比释动能和 HVL 确定水模体的表面剂量。
