Narita Y, Eberl S, Iida H, Hutton B F, Braun M, Nakamura T, Bautovich G
Department of Radiology and Nuclear Medicine, Research Institute for Brain and Blood Vessels, Akita City, Japan.
Phys Med Biol. 1996 Nov;41(11):2481-96. doi: 10.1088/0031-9155/41/11/017.
Scatter correction is a prerequisite for quantitative SPECT, but potentially increases noise. Monte Carlo simulations (EGS4) and physical phantom measurements were used to compare accuracy and noise properties of two scatter correction techniques: the triple-energy window (TEW), and the transmission dependent convolution subtraction (TDCS) techniques. Two scatter functions were investigated for TDCS: (i) the originally proposed mono-exponential function (TDCSmono) and (ii) an exponential plus Gaussian scatter function (TDCSGauss) demonstrated to be superior from our Monte Carlo simulations. Signal to noise ratio (S/N) and accuracy were investigated in cylindrical phantoms and a chest phantom. Results from each method were compared to the true primary counts (simulations), or known activity concentrations (phantom studies). 99mTc was used in all cases. The optimized TDCS(Gauss) method overall performed best, with an accuracy of better than 4% for all simulations and physical phantom studies. Maximum errors for TEW and TDCS(mono) of -30 and -22%, respectively, were observed in the heart chamber of the simulated chest phantom. TEW had the worst S/N ratio of the three techniques. The S/N ratios of the two TDCS methods were similar and only slightly lower than those of simulated true primary data. Thus, accurate quantitation can be obtained with TDCS(Gauss), with a relatively small reduction in S/N ratio.
散射校正是定量单光子发射计算机断层扫描（SPECT）的一个前提条件，但可能会增加噪声。使用蒙特卡罗模拟（EGS4）和物理体模测量来比较两种散射校正技术的准确性和噪声特性：三能量窗（TEW）技术和基于传输的卷积减法（TDCS）技术。针对TDCS研究了两种散射函数：（i）最初提出的单指数函数（TDCSmono）和（ii）一种指数加高斯散射函数（TDCSGauss），我们的蒙特卡罗模拟表明后者更优。在圆柱形体模和胸部体模中研究了信噪比（S/N）和准确性。将每种方法的结果与真实的原始计数（模拟）或已知的活度浓度（体模研究）进行比较。所有情况下均使用99mTc。总体而言，优化后的TDCS（Gauss）方法表现最佳，在所有模拟和物理体模研究中其准确性均优于4%。在模拟胸部体模的心室中，TEW和TDCS（mono）的最大误差分别为-30%和-22%。TEW是这三种技术中信噪比最差的。两种TDCS方法的信噪比相似，仅略低于模拟真实原始数据的信噪比。因此，使用TDCS（Gauss）可以获得准确的定量结果，且信噪比的降低相对较小。
