A prospective gating method to acquire a diverse set of free-breathing CT images for model-based 4DCT.

A prospective gating method to acquire a diverse set of free-breathing CT images for model-based 4DCT. Phys Med Biol. 2018 Jan 19;: Authors: O'Connell D, Ruan D, Thomas DH, Dou TH, Lewis JH, Santhanam AP, Lee PP, Low DA Abstract Breathing motion modeling requires observation of tissues at sufficiently distinct respiratory states for proper 4D characterization. This work proposes a method to improve sampling of the breathing cycle with limited imaging dose. 
 We designed and tested a prospective free-breathing acquisition protocol with a simulation using datasets from 5 patients imaged with a model-based 4DCT technique. Each dataset contained 25 free-breathing fast helical CT scans with simultaneous breathing surrogate measurements. Tissue displacements were measured using deformable image registration. A correspondence model related tissue displacement to the surrogate. Model residual was computed by comparing predicted displacements to image registration results. To determine a stopping criteria for the prospective protocol, i.e. when the breathing cycle had been sufficiently sampled, subsets of N scans where 5<=N<=9 were used to fit reduced models for each patient. A previously published metric was employed to describe the phase coverage, or 'spread,' of the respiratory trajectories of each subset. Minimum phase coverage necessary to achieve mean model residual within 0.5 mm of the full 25-scan model was deter...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research