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Fundamental Study of Heavy Radiography

重型放射线摄影基础研究

基本信息

批准号：
10670864
负责人：
INADA Tetsuo
金额：
$ 2.05万
依托单位：
IBARAKI PREFECTURAL UNIVERSITY OF HEALTH SCIENCES
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Studies of efficacy on heavy ion radiography have been performed in comparison with X-ray radiography. It was suggested that heavy ion radiography gave superior imaging for low contrast tumors at relatively low radiation levels. In heavy ion radiography, small difference of tissue density in deep seated area can be recorded on films as the difference of optical density by using a distal edge of the Bragg peak. This shows that the difference in optical density is related to the difference of the residual range at the film position. The residual range is determined as the integrated stopping power along the path of particle. It was suggested that the two dimensional distribution of relative stopping power could be calculated by the use of a set of data, namely, one dimensional (1D) residual range distributions for the different directions over 360 degrees. The residual range is determined as the accumulated effect of stopping power along the path of charged particle. If we have the set of images showing residual range distribution for the different directions over 360 degrees, the distribution of electron density could be calculated by the use of stopping power formula. This work begin with formulation of algorithm to obtain the CT image of electron density from the spatial distribution of residual range. In the previous study the relations between optical density and residual range and those between optical density and absorbed dose were determined using film system and the difference of residual ranges at each internal organ of small animal. In the present study the fluorescent screen and video-camera with I.I. system was adapted to shorten the image collection time. One dimentional distribution of residual range was obtained from the series of projection images of cylindrical aclylate phantom experimentally by changing thickness of the range shifter.

对重离子射线照相术与X射线照相术进行了对比研究。有人建议，重离子射线照相术在相对较低的辐射水平下对低对比度肿瘤提供了优越的上级成像。在重离子射线照相中，利用布拉格峰的远侧边缘，可以将深部组织密度的微小差异记录在胶片上作为光密度差。这表明光密度的差异与胶片位置处的残留范围的差异有关。剩余射程被确定为沿粒子路径沿着的积分阻止本领。有人建议，相对阻止本领的二维分布可以通过使用一组数据来计算，即，360度上不同方向的一维（1D）剩余射程分布。剩余射程被确定为带电粒子沿着路径的阻止本领的累积效应。如果我们有一组显示360度上不同方向的剩余射程分布的图像，则可以通过使用阻止本领公式来计算电子密度的分布。本工作开始是从剩余距离的空间分布得到电子密度的CT图像的算法的制定。在前期研究中，我们用胶片系统测定了光密度与残留射程、光密度与吸收剂量之间的关系，以及在小动物各脏器的残留射程的差异。本研究采用荧光屏和摄像机，系统进行了调整，以缩短图像采集时间。通过改变距离移位器的厚度，实验性地从圆柱形丙烯酸酯体模的一系列投影图像中获得了剩余距离的一维分布。