Study on Detectors for On-line Measurement and estimation of absorbed energy using SPECT system in Neutron Capture Therapy

中子俘获治疗中SPECT系统吸收能量在线测量和估算探测器的研究

• 批准号: 07558186
• 负责人: KOBAYASHI Tooru
• 金额: $ 3.52万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07558186/
• 关键词: Neutron Capture Therapy; On-line Measurement; SPECT; Prompt Gamma-ray measuement; CdTe Semiconductor; Heavy Water Facility; Lithium Neutron Shielding; 中性子捕捉療法; 半導体検出器; 生体内照射線量分布; 同時測定法; 検出素子; 即発γ線スペクトル; CdTe(カドミウム-テルル)

The purpose of this research is to clarify the feasibility of single photon emission computed tomography system with prompt gamma analysis (named PG-SPECT system), which is expected as an effective real-time measurement method for dose distribution in a living body. We put emphasis on the optimization of the detector material and its size, and the improvement in the system maintenance, such as disuse of the cooling with liquid nitrogen etc., which is usually indispensable to semiconductor detector.In 1995 (Heisei 7), the applicability of Ge semiconductor detector and CdTe semiconductor detector to the PG-SPECT system were studied. Especially, the CdTe detector is thought to be an adequate detector for this system, because of its possibilities of downsizing and disuse of the cooling by the recent remarkable innovation.In 1996 (Heisei 8), the characteristics of CdTe detector at room temperature was estimated, and the effectiveness of the simple cooling method applying Peltier effect was researched by experiments and simulation calculation. It was confirmed that the CdTe detector with the Peltier cooling had great potentialities. Moreover, shielding sheets for thermal neutrons were made using polyethylene mixed with 6LiF,which purchased in 1995, at 30 weight percent, and its effectiveness was confirmed from experiments.In 1997 (Heisei 9), the characteristics evaluation of Ge detector and CdTe detector was continued by experiments and simulation calculations. Furthermore, (1) the reduction of statistical error at low-counts and (2) the collimation system for small-size detector at mixed field of neutrons and gamma-rays were examined. From those results, some research subjects are newly extracted for the next steps.

本研究的目的是阐明单光子发射计算机断层扫描系统与即时伽玛分析（命名为PG-SPECT系统），这是一个有效的实时测量方法在活体剂量分布的可行性。重点对探测器材料和尺寸进行了优化，并对系统维护进行了改进，如取消了液氮冷却等，1995年（平成7年）研究了Ge半导体探测器和CdTe半导体探测器在PG-SPECT系统中的适用性。特别是CdTe探测器，由于最近的显著革新，它有可能实现小型化和不用冷却，因此被认为是该系统的合适探测器。1996年（平成8年），对室温下的CdTe探测器特性进行了估算，并通过实验和模拟计算研究了应用Peltier效应的简单冷却方法的有效性。实验结果表明，采用珀耳帖制冷的碲化镉探测器具有很大的发展潜力。此外，使用1995年购买的6LiF以30wt%混合聚乙烯制成热中子屏蔽板，并通过实验确认了其有效性。1997年（平成9年），通过实验和模拟计算继续进行Ge探测器和CdTe探测器的特性评估。此外，还研究了如何减小低计数时的统计误差和如何设计小探测器在中子和γ射线混合场中的准直系统。从这些结果中，一些研究主题是新提取的下一步。