Bolstad Randy, Brown Jody, Grantham Vesper
Department of Medical Imaging and Radiation Sciences, College of Allied Health, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73117, USA.
J Nucl Med Technol. 2011 Sep;39(3):208-12. doi: 10.2967/jnmt.110.084814. Epub 2011 Jul 27.
SPECT produces nuclear medicine images using a 3-dimensional diagnostic tool that eliminates the superimposition of adjacent structures, thus providing improved disease localization. Another method of uniformity correction-to use the complete capabilities of this tool-is discussed and evaluated in this article. The conventional method of intrinsic uniformity correction accounts only for nonuniformities within the γ-camera, excluding the collimator. If SPECT image quality is related to overall camera performance, then using an extrinsic uniformity correction method rather than an intrinsic method will improve image quality.
SPECT uniformity images were obtained using a SPECT phantom with application of intrinsic and extrinsic uniformity correction tables with 2 different γ-imaging systems. The image results were qualitatively assessed.
Even with acceptable nonuniformity analyses, significant ring artifacts within the intrinsic uniformity-corrected images are observed, whereas the artifacts are considerably less significant with the extrinsic uniformity correction and disappear completely in some of these images.
Extrinsic uniformity correction may significantly improve the overall image quality by taking into account nonuniformities that arise from the collimator. This method will result in fewer image artifacts and improved image quality, thereby improving patient care.
单光子发射计算机断层扫描（SPECT）使用一种三维诊断工具生成核医学图像，该工具可消除相邻结构的重叠，从而改善疾病定位。本文讨论并评估了另一种均匀性校正方法——利用该工具的全部功能。传统的固有均匀性校正方法仅考虑γ相机内部的不均匀性，不包括准直器。如果SPECT图像质量与相机整体性能相关，那么使用外部均匀性校正方法而非固有方法将提高图像质量。
使用带有固有和外部均匀性校正表的SPECT体模，通过2种不同的γ成像系统获取SPECT均匀性图像。对图像结果进行定性评估。
即使非均匀性分析结果可接受，在固有均匀性校正图像中仍观察到明显的环形伪影，而在外部均匀性校正图像中这些伪影明显较少，并且在其中一些图像中完全消失。
通过考虑准直器产生的不均匀性，外部均匀性校正可显著提高整体图像质量。该方法将减少图像伪影并改善图像质量，从而提高患者护理水平。
