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On an attenuation correction using gamma ray TCT for quantitative SPECT imaging

使用伽马射线 TCT 进行定量 SPECT 成像的衰减校正

基本信息

批准号：
05454305
负责人：
KUBO Atsushi
金额：
$ 2.88万
依托单位：
Keio University, School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05454305/
关键词：
Attenuation correcion Image Processing Single Photon Emission CT Transmission CT Monte Carlo method Scatter Correction コリメータ

项目摘要

This study was carried out to obtain quantitative SPECT images by correcting attenuation and scattering of gamma rays.In the attenuation correction, we used Chang's method with an accurate map of linear attenuation coefficients measured by gamma ray fanbeam transmission CT (FTCT).FTCT scanning was performed using a commercially available gamma camera system (Toshiba GCA-9300A) with fanbeam collimators.As an external source for FTCT,we used a Tc-99m line source positioned at the focal point of each fanbeam collimator.Scatter correction was performed by eliminating the counts of scattered photons from each planar image.The method used was the triple energy window (TEW) method, in which the count data were acquired at each pixel using three windows : amain window centered at photopeak energy and two subwindows on both sides of the main window.The scattered photons included in the main window were estimated as a trapezoidal region shaped by the counts of the subwindows and the width of the main window, and were subtracted from the count of the main window.These attenuation and scatter correction methods were evaluated by simulations using a Monte Carlo method and by experiments including phantom studies and preliminary clinical studies.The results of these simulations and experiments showed that quantitative measurement of activity in an object was realized in clinical situations.

为了通过校正伽马射线的衰减和散射来获得定量的SPECT图像。在衰减校正中，我们使用张氏方法和伽马射线扇束透射式CT(FTCT)测量的精确的线性衰减系数图。FTCT扫描使用商用伽马相机系统(Toshiba GCA-9300A)和扇束准直器。作为FTCT的外部源，我们使用位于每个扇束准直器焦点的Tc-99m线源。通过消除每个平面图像的散射光子计数来进行散布校正。所使用的方法是三能窗(Tew)法，其中在每个像素上使用三个窗口：以光峰能量为中心的主窗口和主窗口两侧的两个子窗口来获取每个像素的计数数据；主窗口中包含的散射光子被估计为由子窗口的计数和主窗口的宽度形成的梯形区域，并从主窗口的计数中减去；这些衰减和散射校正方法通过蒙特卡罗方法进行了仿真评估，并通过包括体模研究和初步临床研究在内的实验进行了评估。