Planar Computational Phantom for Modeling First-Pass Scintigraphic Measurement of Right Ventricular Ejection Fraction

A simple planar phantom was developed to model imaging of a radioactivity distribution during the first pass of a radioactive bolus through the right heart. We focused on the components required for computation of right ventricular ejection fraction by modeling the right ventricle and the adjacent two chambers, the right atrium and the pulmonary artery. We used spheres to approximate the atrial and ventricular cavities. We used a rigid cylindrical tube to model the pulmonary artery. The phantom models the accumulation of radioactivity in the atrium, passage of activity into the ventricle, and outflow of activity through the pulmonary artery. Fluid flow is modeled through the pulmonary artery, but not through the atrium and ventricle. An application of the phantom is presented-evaluation of nine-point smoothing of first pass images. This application demonstrates use of such filtering results in objective improvement in image quality and underestimation of ventricular ejection fraction compared to truth. This phantom is the first component of an investigational framework for improvement of right-heart first-pass scintigraphy.