Department of Medical Physics, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura, Kanagawa 247-8533, Japan.
Graduate School of Engineering, Kyoto University, Kyoto University Katsura, Kyoto Nishikyo-ku, Kyoto 615-8246, Japan.
Biomed Phys Eng Express. 2024 May 22;10(4). doi: 10.1088/2057-1976/ad4b1e.
Evaluating neutron output is important to ensure proper dose delivery for patients in boron neutron capture therapy (BNCT). It requires efficient quality assurance (QA) and quality control (QC) while maintaining measurement accuracy. This study investigated the optimal measurement conditions for QA/QC of activation measurements using a high-purity germanium (HP-Ge) detector in an accelerator-based boron neutron capture therapy (AB-BNCT) system employing a lithium target. The QA/QC uncertainty of the activation measurement was evaluated based on counts, reproducibility, and standard radiation source uncertainties. Measurements in a polymethyl methacrylate (PMMA) cylindrical phantom using aluminum-manganese (Al-Mn) foils and aluminum-gold (Al-Au) foils and measurements in a water phantom using gold wire with and without cadmium cover were performed to determine the optimal measurement conditions. The QA/QC uncertainties of the activation measurements were 4.5% for Au and 4.6% for Mn. The optimum irradiation proton charge and measurement time were determined to be 36 C and 900 s for measurements in a PMMA cylindrical phantom, 7.0 C and 900 s for gold wire measurements in a water phantom, and 54 C and 900 s at 0-2.2 cm depth and 3,600 s at deeper depths for gold wire measurements with cadmium cover. Our results serve as a reference for determining measurement conditions when performing QA/QC of activation measurements using HP-Ge detectors at an AB-BNCT employing a lithium target.
评估中子输出对于硼中子俘获治疗（BNCT）中的患者的适当剂量输送非常重要。这需要在保持测量精度的同时进行高效的质量保证（QA）和质量控制（QC）。本研究探讨了使用基于加速器的硼中子俘获治疗（AB-BNCT）系统中的高纯锗（HP-Ge）探测器进行 QA/QC 激活测量的最佳测量条件，该系统采用锂靶。基于计数、再现性和标准辐射源不确定性评估了激活测量的 QA/QC 不确定性。在 PMMA 圆柱形体模中使用 Al-Mn 箔和 Al-Au 箔进行测量，以及在水模中使用带和不带镉覆盖的金丝进行测量，以确定最佳测量条件。激活测量的 QA/QC 不确定性分别为 Au 的 4.5%和 Mn 的 4.6%。确定了最佳辐照质子电荷和测量时间，对于 PMMA 圆柱形体模中的测量，最佳辐照质子电荷和测量时间分别为 36 C 和 900 s，对于水模中的金丝测量，最佳辐照质子电荷和测量时间分别为 7.0 C 和 900 s，对于带有镉覆盖的金丝测量，在 0-2.2 cm 深度的最佳辐照质子电荷和测量时间分别为 54 C 和 900 s，在更深的深度的最佳辐照质子电荷和测量时间为 3600 s。我们的结果为使用基于锂靶的 AB-BNCT 中的 HP-Ge 探测器进行激活测量的 QA/QC 确定测量条件提供了参考。
