Ahmad Munir, Shahzad Tasawar, Masood Khalid, Rashid Khalid, Tanveer Muhammad, Iqbal Rabail, Hussain Nasir, Shahid Abubakar
Institute of Nuclear Medicine and Oncology (INMOL), New Campus Road, Lahore, PC 10068, Pakistan.
Department of Physics, The University of Lahore, Pakistan, 1-KM Raiwind Road, Lahore, 54000, Punjab, Pakistan.
J Digit Imaging. 2016 Jun;29(3):394-402. doi: 10.1007/s10278-015-9853-x.
Emission tomographic image reconstruction is an ill-posed problem due to limited and noisy data and various image-degrading effects affecting the data and leads to noisy reconstructions. Explicit regularization, through iterative reconstruction methods, is considered better to compensate for reconstruction-based noise. Local smoothing and edge-preserving regularization methods can reduce reconstruction-based noise. However, these methods produce overly smoothed images or blocky artefacts in the final image because they can only exploit local image properties. Recently, non-local regularization techniques have been introduced, to overcome these problems, by incorporating geometrical global continuity and connectivity present in the objective image. These techniques can overcome drawbacks of local regularization methods; however, they also have certain limitations, such as choice of the regularization function, neighbourhood size or calibration of several empirical parameters involved. This work compares different local and non-local regularization techniques used in emission tomographic imaging in general and emission computed tomography in specific for improved quality of the resultant images.
发射断层图像重建是一个不适定问题，这是由于数据有限且有噪声，以及各种影响数据的图像退化效应，从而导致重建图像有噪声。通过迭代重建方法进行的显式正则化被认为能更好地补偿基于重建的噪声。局部平滑和保边正则化方法可以减少基于重建的噪声。然而，这些方法会在最终图像中产生过度平滑的图像或块状伪影，因为它们只能利用局部图像特性。最近，为了克服这些问题，通过纳入目标图像中存在的几何全局连续性和连通性，引入了非局部正则化技术。这些技术可以克服局部正则化方法的缺点；然而，它们也有一定的局限性，比如正则化函数的选择、邻域大小或几个相关经验参数的校准。这项工作比较了一般发射断层成像以及特定发射计算机断层成像中用于提高所得图像质量的不同局部和非局部正则化技术。
