Perisinakis K, Karkavitsas N, Damilakis J, Gourtsoyiannis N
Department of Medical Physics, Faculty of Medicine, University of Crete, Greece.
Nuklearmedizin. 1998;37(7):239-44.
To investigate the effect of two scatter correction methods on lesion detectability for both planar and tomographic hepatic imaging.
All planar and tomographic acquisitions involved simultaneous collection of photons in the main photopeak window (126-154 keV) and three additional windows (92-116, 116-126 and 154-164 keV). Uncorrected and corrected for scatter images were obtained from the same acquisition data. The dual energy window (DEW) and the triple energy window (TEW) scatter compensation methods were used to obtain two sets of corrected images. The DEW method was implemented with main photopeak window 126-154 keV, Compton scatter window 92-126 keV and scatter multiplier k = 0.5. A modified TEW method was also applied with main photopeak window 126-154 keV and scatter subwindows 116-126 keV and 154-164 keV. Phantoms were used to study the effect of scatter correction on contrast and signal-to-noise ratio. The observer's ability to identify lesions was studied on uncorrected and corrected for scatter patient images.
In planar imaging, both scatter compensation methods yielded contrast enhancement. However signal to noise ratio (SNR) was degraded to 0.63 and 0.67 when DEW and TEW were applied respectively. In SPECT images, contrast was increased by a factor of 2.4 and 1.7, while SNR was degraded to 0.60 and 0.64 when DEW and TEW methods were used respectively.
Scatter correction using DEW and TEW methods may improve observer's ability to distinguish lesions in planar (p < 0.05 for both methods) and SPECT (p < 0.05 for both methods) liver studies.
研究两种散射校正方法对肝脏平面成像和断层成像中病变可检测性的影响。
所有平面和断层采集均涉及在主要光电峰窗口（126 - 154 keV）以及另外三个窗口（92 - 116、116 - 126和154 - 164 keV）同时采集光子。从相同的采集数据中获取未校正和经散射校正的图像。采用双能窗（DEW）和三能窗（TEW）散射补偿方法获得两组校正图像。DEW方法在主要光电峰窗口126 - 154 keV、康普顿散射窗口92 - 126 keV以及散射乘数k = 0.5的条件下实施。还应用了一种改进的TEW方法，主要光电峰窗口为126 - 154 keV，散射子窗口为116 - 126 keV和154 - 164 keV。使用体模研究散射校正对对比度和信噪比的影响。在未校正和经散射校正的患者图像上研究观察者识别病变的能力。
在平面成像中，两种散射补偿方法均提高了对比度。然而，分别应用DEW和TEW时，信噪比分别降至0.63和0.67。在SPECT图像中，对比度分别提高了2.4倍和1.7倍，而分别使用DEW和TEW方法时，信噪比分别降至0.60和0.64。
使用DEW和TEW方法进行散射校正可能会提高观察者在肝脏平面（两种方法p均< 0.05）和SPECT（两种方法p均< 0.05）研究中区分病变的能力。
