  Motion imaging phantoms are expensive, bulky and difficult to transport and
set-up. The purpose of this paper is to demonstrate a simple approach to the
design of multi-modality motion imaging phantoms that use mechanically stored
energy to produce motion. We propose two phantom designs that use mainsprings
and elastic bands to store energy. A rectangular piece was attached to an axle
at the end of the transmission chain of each phantom, and underwent a rotary
motion upon release of the mechanical motor. The phantoms were imaged with MRI
and US, and the image sequences were embedded in a 1D non linear manifold
(Laplacian Eigenmap) and the spectrogram of the embedding was used to derive
the angular velocity over time. The derived velocities were consistent and
reproducible within a small error. The proposed motion phantom concept showed
great potential for the construction of simple and affordable motion phantoms
