Development of scatter correction for quantitative SPECT imaging

通过消除平面图像中散射光子的计数来重建定量SPECT图像。我们已经开发了一种新的散射校正方法，考虑到局部散射分数的平面图像。在该方法中，通过使用三个窗口在每个像素处获取计数数据：以峰值能量为中心的主窗口和主窗口两侧的两个子窗口。包括在主窗口中的散射光子被估计为由子窗口的计数和主窗口的宽度成形的梯形区域。通过从利用主窗口采集的光子的计数中减去这些光子的计数，可以估计每个像素的初级光子的计数。该方法进行了评估，通过蒙特卡罗模拟使用数值幻影。模拟实验表明，由未散射光子重建的放射性分布与由修正数据重建的放射性分布之间具有良好的一致性。然后，我们使用市售的伽马照相机系统（东芝GCA-9300 A）配备了特殊的硬件进行了体模研究和初步的临床研究。在临床研究中，我们使用了一种新的Tc-99 m心肌灌注显像剂（P-53）。结果表明，该方法可以在不增加数据采集和处理时间的情况下对放射性活度进行定量测量，也适用于常规的放射性活度图和多峰放射性核素研究。

The study was carried out to reconstruct a quantitative SPECT image by eliminating the counts of scattered photons from a planar image. We have developed a new scatter correction method considering the local scatter fraction of the planar image. In this method, the count data are acquired at each pixel by using three windows: a main window centered at photopeak energy and two subwindows on both sides of the main window. The scattered photons included in the main window are estimated as a trapezoidal region shaped by the counts of the subwindows and the width of the main window. By subtracting the count of those photons from that acquired with the main window, the count of the primary photons can be estimated for each pixel. The method was evaluated by a Monte Carlo simulation using numerical phantoms. The simulation tests showed good agreement between the activity distributions reconstructed from unscattered photons and those reconstructed from corrected data by the proposed method. Then we made phantom studies and preliminary clinical studies using a commercially available gammacamera system (Toshiba GCA-9300A) equipped with special hardware. In the clinical studies we used a new Tc-99m myocardial perfusion imaging agent (P-53). These results showed that quantitative measurement of activity in clinical study is possible without adding data acquisition/processing time.The method is also applicable to conventional scintigrams and to multi-photopeak radionuclide studies.