权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

New methods of radiation dosimetry in medicine by using optical fibers

利用光纤进行医学辐射剂量测定的新方法

基本信息

批准号：
09680476
负责人：
AOYAMA Takahiko
金额：
$ 1.73万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

The purpose of the present study is the development of novel radiation dosimeters and new methods of radiation dosimetry in medicine by using optical fiber as detector material of x-ray dosimeters. The study was focused on the following three developments.1. A long dosimeter on the order of one meter was devised by using a plastic scintillating fiber as detector material for measuring dose integral by x-ray CT exposure on a human phantom along lines parallel to the axis of rotation of the x-ray source. Uniform sensitivity of the dosimeter was attained over a range of about one meter by processing light signals derived from both ends of the fiber. Measurements of CT doses with the long dosimeter indicated the underestimation of saturated dose integral that had been obtained with conventional CT chambers with a short detection length.2. A small sized and tissue equivalent detector consisting of a plastic scintillating fiber chip coupled with an optical fiber light guide was devised for the precise dosimetry of small field therapeutic x-ray beams. Light output from the detector was converted to electrical signal with unity gain photodiodes without using photomultipliers, and a novel method to estimate absorbed dose from pulse height spectra was developed to obtain dose values with a large signal-to-noise ratio and excellent reproducibility.3. A small sized and highly sensitive x-ray detector with directional independence of response was devised for the dosimetry of CT exposure by using a plastic scintillation fiber chip and a pair of optical fiber light guides. Dose profiles in a human chest phantom along lines parallel to the axis of rotation of the x-ray source and point doses at various positions in the phantom were measured for helical CT examinations to estimate tissue or organ doses.

本研究的目的是利用光纤作为X射线剂量计的探测材料，开发新型的辐射剂量计和医用辐射剂量测量的新方法。这项研究的重点是以下三个方面的发展。利用塑料闪烁光纤作为探测器材料，设计了一种长达一米的剂量计，用于测量人体体模上平行于X射线源旋转轴线的X射线CT剂量积分。通过处理来自光纤两端的光信号，在大约一米的范围内获得了剂量计的均匀灵敏度。用长剂量计对CT剂量的测量表明，用短探测长度的常规CT室获得的饱和剂量积分被低估了。为了精确测量小野治疗性X射线的剂量，设计了一种由塑料闪烁光纤芯片和光纤光导耦合而成的小型组织当量探测器。在不使用光电倍增管的情况下，将探测器输出的光转换为单位增益光电二极管的电信号，并提出了一种从脉冲高度谱估计吸收剂量的新方法，以获得信噪比高、重复性好的剂量值。利用塑料闪烁光纤芯片和一对光纤光导设计了一种用于CT照射剂量测量的小尺寸、高灵敏度、与响应方向无关的X射线探测器。测量了人体胸部体模中平行于X射线源旋转轴线的剂量分布和体模中不同位置的点剂量，以用于螺旋CT检查以估计组织或器官的剂量。