Dynamic digital phantoms

The construction parameters and the composition of phantoms are strictly specified. Hence comparing the results from repeated imaging of a phantom with different imaging parameters allows isolation of the effect of the varied parameter. With this knowledge one can assign settings for optimum imaging of that particular phantom. Ideally the phantom would be exactly the same for every scan to allow easy comparison. However in some cases natural degradation of the materials involved means that the results will change slowly over time and designers of phantoms often attempt to select materials to reduce this degradation. However the nature of the physical processes involved in the imaging modality limits the range of possible materials available for construction, potentially making it impossible to eliminate degradation. This is especially true in the case of multi-modality phantoms in which the material choice may be very severely limited. However, if the degradation is very slow, is measured before use or is factored into the image evaluation, then it can be managed.