An optimization of reconstruction parameters and investigation into the impact of photon scatter in 67Ga SPECT
An optimization of reconstruction parameters and investigation into the impact of photon scatter in 67Ga SPECT
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DOI：
10.1109/tns.2002.803786
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发表时间：
2002-10-01
影响因子：
1.8
通讯作者：
King, MA
中科院分区：
文献类型：
--
作者：
Farncombe, TH;Gifford, HC;King, MA
在Ga-67柠檬酸盐SPECT成像过程中，光子会从高能光子向下散射到低能量采集窗口，从而可能对重建图像质量产生不利影响。由于这些额外的散射光子存在于投影数据中，使用更复杂的重建策略，如三维探测器响应补偿（3-D DRQ）和衰减校正（AC）的效果尚不清楚。结合数值信道化Hotelling观察员（CHO）和人类定位接收器工作特征（LROC）研究，发现当投影数据使用重标块迭代（RBI）算法的两次迭代（包括三维DRC和患者特定AC）重建时，病变可检测性达到最大，然后进行重建后的低通三维高斯滤波，FWHM约为1 cm。这些参数偏离了原始光子投影数据的最佳重建参数，该数据发现，在使用相同的3-D DRC、AC和后滤波进行4次RBI迭代后，最大程度地检测到病变。正如预期的那样，还观察到当Ga-67投影数据中存在散射光子时，与仅原始光子重建相比，肿瘤可检测性降低（最大A(L)从0.79降低到0.58）。这种减少在人类LROC和数值观察者研究中都有统计学意义，这表明在Ga-67柠檬酸盐成像过程中需要散射补偿。
During Ga-67 citrate SPECT imaging, photon downscatter will occur from higher energy photons into lower energy acquisition windows thus possibly adversely affecting reconstructed image quality. With these additional scattered photons present in projection data, the effect of using more complex reconstruction strategies such as three-dimensional detector response compensation (3-D DRQ and attenuation correction (AC) is unclear.Using a combination of numerical Channelized Hotelling Observers (CHO) and human localization receiver operating characteristics (LROC) studies it has been found that maximum lesion detectability occurs when projection data is reconstructed using two iterations of the rescaled block iterative (RBI) algorithm with both 3-D DRC and patient specific AC, followed by a postreconstruction low-pass 3-D Gaussian filtering with a FWHM of approximate to 1 cm. These parameters deviate from optimal reconstruction parameters for primary photon-only projection data which finds that maximum lesion detection occurs after 4 RBI iterations with the same 3-D DRC, AC, and postfiltering. As expected, it is also observed that decreased tumor detectability results when scattered photons are present in Ga-67 projection data compared to primary photon only reconstructions (reducing maximum A(L) from 0.79 to 0.58). This decrease has been found to be statistically significant in both human LROC and numerical observer studies, suggesting the need for scatter compensation during Ga-67 citrate imaging.