A phantom for simulating fast dynamic studies on a gamma camera

Increasing numbers of dynamic studies are undertaken using gamma cameras, and many of these, like isotope angiography, have very rapid time scales. A simple, useful, easily standardized, dynamic phantom has been developed to allow calibration studies to be made on parameters such as time resolution, display intensity and photographic exposure settings. The phantom consists of a source swinging as a simple pendulum and suspended over the camera collimator. A simple driving system maintains a constant pendulum amplitude. A description is given of an example of the use of the phantom in the simulation of left ventricular ejection fraction curves provided by the oscillation of a 3mCi 99Tcsup(m) pendulum source over a waisted lead aperture placed on the collimator. The method has been extended to provide a technique for testing physiological triggering systems by incorporating a photoelectric cell which provides a triggering pulse when the pendulum crosses its axis. The method provides a simple and realistic test for the reliability of the complete imaging and recording system. (U.K.)