title: Comparison Between Pre-Log and Post-Log Statistical Models in Ultra-Low-Dose CT Reconstruction.
abstract: X-ray detectors in clinical computed tomography (CT) usually operate in current-integrating mode. Their complicated signal statistics often lead to intractable likelihood functions for practical use in model-based image reconstruction (MBIR). It is therefore desirable to design simplified statistical models without losing the essential factors. Depending on whether the CT transmission data are logarithmically transformed, pre-log and post-log models are two major categories of choices in CT MBIR. Both being approximations, it remains an open question whether one model can notably improve image quality over the other on real scanners. In this study, we develop and compare several pre-log and post-log MBIR algorithms under a unified framework. Their reconstruction accuracy based on simulation and clinical datasets are evaluated. The results show that pre-log MBIR can achieve notably better quantitative accuracy than post-log MBIR in ultra-low-dose CT, although in less extreme cases, post-log MBIR with handcrafted pre-processing remains a competitive alternative. Pre-log MBIR could play a growing role in emerging ultra-low-dose CT applications.
authors.lastname: Lin Fu
authors.lastname: Tzu-Cheng Lee
authors.lastname: Soo Mee Kim
authors.forename: Adam M
authors.initials: AM
authors.lastname: Alessio
authors.forename: Paul E
authors.initials: PE
authors.lastname: Kinahan
authors.lastname: Zhiqian Chang
authors.forename: Ken
authors.initials: K
authors.lastname: Sauer
authors.forename: Mannudeep K
authors.initials: MK
authors.lastname: Kalra
authors.forename: Bruno
authors.initials: B
authors.lastname: De Man
mesh_terms: D000328:Adult; D000465:Algorithms; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D015233:Models, Statistical; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*