Boron neutron capture therapy for the treatment of cerebral gliomas. I. Theoretical evaluation of the efficacy of various neutron beams.
Boron neutron capture therapy for the treatment of cerebral gliomas. I. Theoretical evaluation of the efficacy of various neutron beams.
复制标题
硼中子俘获疗法用于治疗脑胶质瘤。
DOI：
10.1118/1.594168
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发表时间：
1975
期刊：
影响因子：
3.8
通讯作者：
E. Tolpin
中科院分区：
文献类型：
--
作者：
R. Zamenhof;B. Murray;G. Brownell;G. Wellum;E. Tolpin
硼中子俘获疗法治疗脑胶质瘤的技术依赖于选择性装载的肿瘤与10 B-富集化合物和随后的低能量中子照射的大脑。在10 B（n，α）7 Li反应中产生的带电粒子在组织中的范围小于10 μ m，使得剂量分布紧密地遵循10 B分布，甚至到细胞水平。这种治疗过程的有效性不仅取决于10 B化合物，而且还取决于中子源的光谱特性。因此，这些特征的优化将增加治疗成功的机会。用中性粒子输运程序计算了五种不同入射中子束在一个简单头部模型内的剂量深度分布。通过使用最大可用深度标准对这些光束进行比较，以确定其相对治疗效果。特别地，利用目前可用的化合物，MIT反应堆（MITR）治疗射束（a）不劣于纯热中子射束，（b）如果消除其伽马射线污染，则将略微改善，（c）上级部分10 B过滤的MITR射束，和（d）产生最大可用深度，该深度强烈地依赖于肿瘤-血中10 B浓度比值与肿瘤中10 B绝对浓度呈弱相关性。平均能量为37 eV的纯超热中子束具有接近硼中子俘获治疗的最佳特性。然而，这些最佳特性可以通过明智的D2 O慢化和10 B过滤的252 Cf中子源来近似。对于实际的10 B浓度，这种定制的252 Cf源的最大可用深度比MITR治疗束至少大1.5 cm。然而，至少需要1克252 Cf才能使其成为实用的治疗源。如果慢化的252 Cf源没有被10 B过滤，则所得到的中子束具有与没有伽马射线污染的MITR束相似的特性。对于usch束，100 mg的252 Cf将产生2.4 × 10（8）中子/（cm 2 sec）的通量，这是适合于治疗应用的强度。
The technique of boron neutron capture therapy in the treatment of cerebral gliomas depends upon the selective loading of the tumor with a 10B-enriched compound and subsequent irradiation of the brain with low-energy neutrons. The charged particles produced in the 10B (n,alpha) 7Li reaction have ranges in tissue of less than 10 mum so that the dose distribution closely follows the 10B distribution even to the cellular level. The effectiveness of this therapy procedure is dependent not only on the 10B compound but on the spectral characteristics of the neutron source as well. Hence, an optimization of these characteristics will increase the chances of therapeutic success. Transport calculations using a neutral particle transport code have been made to determine the dose-depth distributions within a simple head phantom for five different incident neutron beams. Comparison of these beams to determine their relative therapeutic efficacy was made by the use of a maximum useable depth criterion. In particular, with presently available compounds, the MIT reactor (MITR) therapy beam (a) is not inferior to a pure thermal neutron beam, (b) would be marginally improved if its gamma-ray contamination were eliminated, (c) is superior to a partially 10B-filtered MITR beam, and (d) produces a maximum useable depth which is strongly dependent upon the tumor-to-blood ratio of 10B concentrations and weakly dependent upon the absolute 10B concentration in tumor. A pure epithermal neutron beam with a mean energy of 37 eV is shown to have close to the optimal characteristics for boron neutron capture therapy. Futhermore, these optimal characteristics can be approximated by a judiciously D2O moderated and 10B-filtered 252Cf neutron source. This tailored 252Cf source would have at least a 1.5 cm greater maximum useable depth than the MITR therapy beam for realistic 10B concentrations. However, at least one gram of 252Cf would be needed to make this a practical therapy source. If the moderated 252Cf source is not 10B filtered, the resultant neutron beam has characteristics similar to those of the MITR beam with no gamma-ray contamination. For usch a beam, 100 mg of 252Cf would produce a flux of 2.4 X 10(8) neutrons/(cm2 sec), which is an intensity suitable for therapy applications.