Study on measuring device arrangement of array-type CdTe detector for BNCT-SPECT
Study on measuring device arrangement of array-type CdTe detector for BNCT-SPECT
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DOI：
10.1016/j.rpor.2015.04.002
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发表时间：
2016-03-01
影响因子：
1.2
通讯作者：
Murata, Isao
中科院分区：
文献类型：
--
作者：
Manabe, Masanobu;Nakamura, Soichiro;Murata, Isao
目的：设计BNCT-SPECT阵列式CdTe探测器测量装置。背景：在硼中子俘获治疗中，存在一个非常严重的问题，即BNCT的治疗效果无法在辐照过程中真实的实时获知。因此，我们一直在开发一种所谓的BNCT-SPECT与CdTe探测器，它可以获得三维图像的BNCT治疗效果，通过测量478 keV的γ射线发射的激发态的7 Li核产生的B-10（n，α）反应。然而，目前还没有实现实际应用，因为BNCT-SPECT对空间分辨率、测量时间、统计精度和能量resolution.Materials和Methods的要求非常苛刻。设计研究是通过三维输运程序MCNP 5进行的数值模拟进行的，考虑了探测器组件、辐照室和均匀排列的CdTe晶体。478 keV伽马射线的估计计数率足够大，大于超过1000计数/h的目标值。然而，S/N比没有达到S/N > 1的目标。我们证实，S/N比的恶化是由康普顿散射的影响，特别是由于捕获的γ射线的氢。理论计算结果表明，反符合效应可能会增加探测器的信噪比，但反符合效应对探测器的信噪比影响不大。在下一阶段中，将制作具有两个CdTe晶体的阵列探测器，以测试去除反符合事件的可能性。(C)2015年大波兰癌症中心。由Elsevier Sp. z o.o.发布All rights reserved.
Aim: To design the measuring device arrangement of array-type CdTe detector for BNCT-SPECT.Background: In a boron neutron capture therapy, a very serious unsolved problem exists, namely that the treatment effect for BNCT cannot be known during irradiation in real time. Therefore, we have been developing a so-called BNCT-SPECT with a CdTe detector, which can obtain a three-dimensional image for the BNCT treatment effect by measuring 478 keV gamma-rays emitted from the excited state of 7Li nucleus created by the B-10(n,alpha) reaction. However, no practical uses were realized at present, because BNCT-SPECT requires very severe conditions for spatial resolution, measuring time, statistical accuracy and energy resolution.Materials and methods: The design study was performed with numerical simulations carried out by a 3-dimenaional transport code, MCNP5 considering the detector assembly, irradiation room and even arrangement of arrayed CdTe crystals.Results: The estimated count rate of 478 keV gamma-rays was sufficiently large being more than the target value of over 1000 counts/h. However, the S/N ratio did not meet the target of S/N > 1. We confirmed that deterioration of the S/N ratio was caused by the influence of Compton scattering especially due to capture gamma-rays of hydrogen. Theoretical calculations were thereafter carried out to find out whether anti-Compton measurement in an array-type CdTe detector could decrease the noise due to Compton scatterings.Conclusions: The calculation result showed that the anti-coincidence would possibly increase the S/N ratio. In the next phase, an arrayed detector with two CdTe crystals will be produced to test removal possibility of the anti-coincident event. (C) 2015 Greater Poland Cancer Centre. Published by Elsevier Sp. z o.o. All rights reserved.