Hybrid phantoms for testing the measurement of regional dynamics in dynamic renal scintigraphy.

A hybrid phantom is a synthetic dynamic scintigraphic study reconstructed from dynamic components of real clinical data. The aim of a hybrid simulation is to provide realistic reference studies with systematically varying quantitative diagnostic parameters for testing the quality of measurement of regional dynamics. The components of the phantom are extracted from a representative patient study using factor analysis. Prior to the construction of the phantom, selected components are modified in a known way or substituted with heterologous data. The phantom study is constituted from the altered components using a procedure inverse to factor analysis, and completed by the addition of residual noise. The hybrid phantom is a compromise between simulated and software phantoms. Unlike simulated phantoms, it preserves a significant part of data variability and the natural complex structure of scintigraphic images. Unlike software phantoms, it provides values for selected diagnostic parameters or magnitudes of their relative changes. A set of hybrid phantoms from a dynamic renal study and the results of a pilot clinical evaluation are presented.