Theoretical noise estimation in 3D X-ray cone-beam CT reconstruction

Many researchers have been studying on the noise properties and image quality influence on system performance for tomographic imaging in recent years. Most of the works are focused on 2D nuclear medicine imaging. Since X-ray CT dosage has been pushed to a lower level and 3D imaging has been a trend, it is necessary to study the performance of 3D X-ray CT systems. In this work, we presented a new theoretical estimation method for a critical noise property: covariance, of the classical FDK reconstructions for 3D X-ray CT. The method is easy to implement. The theory is validated by numerical MC simulation. Our results confirm that theoretical estimation of covariance and variance in CT image reconstruction match the MC result well. Hence, the propose method can exempt us from computationally expensive MC studies.