Characterizing Accuracy in 4 DCT Deformable Registration Using the POPI Model

Materials/Methods Two real-patient 4DCT phantom datasets from the POPI model(2,3) were used to test the SERIAL and DIRECT registration methods (Figure 1). One POPI model (patient1) displayed typical respiratory motion, 6.3mm +/3.0mm while the other (patient2) displayed significant respiratory motion, 14.0mm +/7.2mm, between endexpiration and end-inspiration (Figure 2). The phantoms were also used to study the relationship between initial rigid registration error and residual registration error after deformation. Distances were measured between corresponding points in the 0% and 50% phase images after rigid and deformable registration. The residual registration error was measured as the distance between corresponding points after deformation.